Papers for Tuesday, Sep 23 2025

The 21-cm signal from the Epoch of Reionization (EoR) is a powerful probe of the evolution of the Universe. However, accurate measurements of the EoR signal from radio interferometric observations are sensitive to efficient foreground removal, mitigating radio-frequency interference and accounting for instrumental systematics. This work represents the first in a series of papers, where we will be introducing a novel ML based pipeline, step-by-step, to directly infer reionization parameters from 21-cm radio-interferometric images. In this paper, we investigate the impact of the variations in the point spread function (PSF) on parameter estimation by simulating visibilities corresponding to input 21-cm maps as observed by the 128-antenna configuration of the Murchison Widefield Array (MWA) Phase II. These visibilities are imaged to obtain dirty images, which are then used to train a 2D convolutional neural network (CNN) to predict $\rm x_{HI}$. To systematically assess the effect of PSF mis-modelling, we generate multiple test sets by varying the MWA's antenna layout, thereby introducing controlled variations in the PSF; we then feed these alternative PSF dirty images to our CNN trained using only dirty images with the PSF of the true antenna layout. Our results demonstrate that PSF variations introduce biases in the CNN's predictions of $\rm x_{HI}$, with errors depending on the extent of PSF distortion. We quantify these biases and discuss their implications for the reliability of machine-learning-based parameter inference in 21-cm cosmology and how they can be utilized to improve the robustness of estimation against PSF-related systematics in future 21-cm surveys. In concluding, we also discuss how this approach to incorporating realistic instrument error into an ML analysis pipeline can be expanded to include multiple other effects.

We present a study of unbiased reconstruction of cosmic microwave background (CMB) polarization maps from data collected by modern ground-based observatories. Atmospheric emission is a major source of correlated noise in such experiments, complicating the recovery of faint cosmological signals. We consider estimators that require minimal assumptions about unpolarized atmospheric emission properties, instead exploiting hardware solutions commonly implemented in modern instruments, such as pairs of orthogonal antennas in each focal plane pixel, and polarization signal modulation via a continuously rotating half-wave plate (HWP). We focus on two techniques: (i) statistical down-weighting of low-frequency atmospheric signals, and (ii) pair-differencing (PD), which involves differencing signals collected by two detectors in the same focal plane pixel. We compare their performance against the idealized case where the atmospheric signal is perfectly known and cleanly subtracted. We show that PD can be derived from maximum likelihood principles under general assumptions about the atmospheric signal, optimizing map sensitivity. In the absence of instrumental systematics but with reasonable detector noise variations, PD yields polarized sky maps with noise levels only slightly worse than the ideal case. While down-weighting could match this performance, it requires highly accurate atmospheric models that are not readily available. PD performance is affected by instrumental systematics, particularly those leaking atmospheric signal to the difference time stream. However, effects like gain mismatch are efficiently mitigated by a rotating HWP, making PD a competitive, robust, and efficient solution for CMB polarization mapmaking without atmospheric modeling.

Quasi-periodic eruptions (QPEs) are recurring X-ray bursts originating from the vicinity of supermassive black holes, but their driving mechanisms remain under debate. This study analyzes new NICER observations of QPEs in Ansky (a transient event in the nucleus of the galaxy SDSS J1335+0728), taken between January and June 2025. By examining flare durations, peak-to-peak recurrence times, and profiles, we compare the 2025 data with those from 2024 to investigate changes in energy, timescales, and flare shapes. The 2025 QPEs are found to be four times more energetic, with recurrence times of approximately 10 days and flare durations ranging from 2.5 to 4 days, making them both about twice as long as in 2024. Additionally, the flare profiles have become more asymmetric, showing longer decays. We explore different theoretical scenarios to explain the observed properties of the QPEs in Ansky, including evolving stream-disk interactions in an extreme mass-ratio inspiral (EMRI) system as a potential mechanism behind the observed changes in recurrence time and energetics, while also considering alternative models based on mass transfer and accretion disk instabilities. Continued observational efforts will be crucial for unveiling the nature of Ansky.

The core of a massive star (M > 8 Msun) eventually collapses. This implosion usually triggers a supernova (SN) explosion that ejects most of the stellar envelope and leaves behind a neutron star (NS) with a mass of up to about 2 Msun. Sometimes the explosion fails and a black hole forms instead. The NS radiates its immense binding energy (some 10% of its rest mass or $2-4\times10^{53}$ erg) almost entirely as neutrinos and antineutrinos of all flavors with typical energies of some 10 MeV. This makes core-collapse SNe the most powerful neutrino factories in the Universe. Such a signal was observed once - with limited statistics - from SN 1987A in the Large Magellanic Cloud. Today, however, many large neutrino detectors act as SN observatories and would register a high-statistics signal. A future Galactic SN, though rare (1-3 per century), would produce a wealth of astrophysical and particle-physics information, including possible signatures for new particles. Neutrinos are key to SN dynamics in the framework of the Bethe-Wilson delayed explosion paradigm. After collapse, they are trapped in the core for a few seconds, forming a dense neutrino plasma that can exhibit collective flavor evolution caused by the weak interaction, a subject of intense theoretical research.

We present new Hubble Space Telescope (HST) imaging of three recently discovered star-forming dwarf galaxies beyond the Local Group: Pavo, Corvus A, and Kamino. The discovery of Kamino is reported here for the first time. They rank among the most isolated faint dwarf galaxies known, hence they provide unique opportunities to study galaxy evolution at the smallest scales, free from environmental effects of more massive galaxies. Our HST data reach $\sim$2-4 magnitudes below the tip of the red giant branch for each dwarf, allowing us to measure their distances, structural properties, and recent star formation histories (SFHs). All three galaxies contain a complex stellar population of young and old stars, and are typical of field galaxies in this mass regime ($M_V=-10.62\pm0.08$ and $D=2.16^{+0.08}_{-0.07}$ Mpc for Pavo, $M_V=-10.91\pm0.10$ and $D=3.34\pm0.11$ Mpc for Corvus A, and $M_V=-12.02\pm0.12$ and $D=6.50^{+0.15}_{-0.11}$ Mpc for Kamino). Our HST-derived SFHs reveal differences among the three dwarfs: Pavo and Kamino show relatively steady, continuous star formation, while Corvus A formed $\sim$$60$% of its stellar mass by 10 Gyr ago. These results align with theoretical predictions of diverse evolutionary pathways for isolated low-mass galaxies.

Synchrotron emission is seen in a vast array of astrophysical transients, such as gamma-ray bursts (GRBs), radio supernovae, neutron star (NS) mergers, tidal disruption events (TDEs), and fast blue optical transients (FBOTs). Despite the ubiquity of synchrotron-emitting sources, modeling of the emergent flux from these events often relies on simplified analytic approximations. These approximations are inaccurate for high-velocity shocks, where special-relativistic effects are important. Properly incorporating these effects considerably complicates calculations, and generally requires a numerical treatment. In this work we present a novel numerical model which solves the full radiative-transfer problem in synchrotron-emitting shocks, accounting for all relativistic effects. This `full-volume' model is capable of calculating synchrotron emission from a shock of arbitrary velocity, and is designed to be flexible and applicable to a wide range of astrophysical sources. Using this new code, we evaluate the accuracy of more commonly-used approximate models. We find that the full-volume treatment is generally necessary once the shock proper-velocity exceeds $(\Gamma\beta)_{\rm sh}\gtrsim 0.1$, and that approximate models can be inaccurate by $\gtrsim$ an order-of-magnitude in trans-relativistic shocks. This implies that there may be a bias in the inferred physical properties of some FBOTs, jetted TDEs, and other relativistic explosions, where approximate analytic models are typically employed. The code associated with our model is made publicly available, and can be used to study the growing population of relativistic synchrotron-emitting transients.

We investigate the anisotropic stress parameter, $\eta=\Psi/\Phi$, defined as the ratio of the gravitational potentials in the linearly perturbed Friedmann-Lemaître Robertson-Walker metric, as a probe of deviations from general relativity across astrophysical to cosmological scales. Using mass profiles reconstructed from high-precision lensing and kinematics of nine galaxy clusters from the CLASH-VLT sample, we derive $\eta(r)$ as a function of the radial distance from the cluster centres, over the range $[0.1 \,\text{Mpc},1.2\,r_{200}^L]$, where $r_{200}^L$ is virial radius best-fit from lensing data. When using a Navarro-Frenk-White or an Hernquist profile to model the total matter distribution, we find consistency with general relativity ($\eta = 1$) within $2\sigma$ for the full radial range for all the sampled clusters. However, adopting a Burkert profile introduces mild tension with general relativity, reaching the $3\sigma$ level in two systems. Assuming a negligible time-dependence in the redshift range spawned by the clusters, we obtain the joint constraint $\eta (r= 1.0 \, \text{Mpc}) = 0.93^{+0.48}_{-0.40}$ (stat) $\pm 0.47$ (syst) at $95\% $ confidence level -- an improvement of approximately $40\%$ over previous estimates. We discuss the impact of systematics on the constraints, and we highlight the implications of this result for current and upcoming cluster surveys.

Two leading hypotheses for hot Jupiter migration are disk migration and high-eccentricity migration (HEM). Stellar obliquity is commonly used to distinguish them, as high obliquity often accompanies HEM. However, low obliquity does not guarantee disk migration, due to possible spin-orbit realignment or coplanar HEM. Seeking a proxy for disk migration, we investigate the idea that when the circularization timescale of a planet on circular orbit is longer than its age ($\tau_\mathrm{cir} > \tau_\mathrm{age}$), HEM would not have had sufficient time to complete, favoring disk migration. We empirically calibrate the reduced planetary tidal quality factor to be $Q_\mathrm{p}=4.9^{+3.5}_{-2.5}\times10^5$ using the eccentricity distribution of 500+ Jovian mass ($0.2M_\mathrm{J}<M_\mathrm{p}<13M_\mathrm{J}$) planets with measured masses and radii, a value consistent with solar system Jupiter. We then calculate $\tau_\mathrm{cir}$ and identify dozens of disk migration candidates ($\tau_\mathrm{cir} > \tau_\mathrm{age}, \ e < 0.1$). These planets show three notable trends. We first find a clear cutoff of obliquity at $\tau_\mathrm{cir} \sim \tau_\mathrm{age}$, suggesting the primordial alignment of protoplanetary disks. Secondly, we find that among hot Jupiters ($a<0.1$ au), nearby companions are preferentially found around disk migration candidates, suggesting that either HEM dominates hot Jupiter formation, or disk migration also disrupts nearby companions at short separations. Finally, we find a possible dearth of disk migration candidates around mass ratio $\log q \sim -3.2$, consistent with a similar dip suggested at longer orbits from microlensing. The lack of planets across different orbital distance, if true, could be interpreted as a hint of runaway migration.

Recent work has established large samples of astrometrically confirmed RR Lyrae and type-II Cepheid members of Galactic globular clusters (GCs). Any given GC can contain multiple such stars at once, notably RR Lyrae stars pulsating in the fundamental mode (RRab) or the first overtone (RRc), and type-II Cepheids (T2Cep) of BL Her and W Vir types. Here, we present the first joint calibration of the Leavitt laws (LLs) exhibited by 802 RRab, 345 RRc, and 21 T2Cep stars anchored to trigonometric parallaxes. Using the third data release of the ESA Gaia mission (GDR3), we have calibrated the intercepts of the RRab and RRc Leavitt laws in the reddening-free Gaia Wesenheit magnitude to better than 1.0% in distance, and that of T2Cep to 1.3%, using a global fit to all data. The absolute scale is set by 37 nearby GCs with high-accuracy parallaxes while 56 additional GCs provide constraints on LL slopes as well as the LL intercept differences of RRc and T2Cep relative to RRab stars. Our global fit yields homogeneous high-accuracy distances of 93 GCs that show no evidence of bias for Gaia parallaxes of distant GCs. Control of systematics was demonstrated by 31 alternative fit variants, notably involving different treatments of metallicity effects, as well as by Markov Chain Monte Carlo analysis. Our results suggest that photometric metallicities of RR Lyrae stars require further improvements while also exhibiting possible signs of intra-cluster chemical inhomogeneity. This work lays the foundation for exploiting RRab, RRc, and T2Cep stars as high-accuracy standard candles for near-field cosmology and the extragalactic distance scale.

Determining the habitability of terrestrial exoplanets is a complex problem that represents the next major step for the astrophysical community. The majority of current models treat these planets as homogeneous or contain heterogeneity that is constant in time. In reality, habitable exoplanets are expected to contain atmospheric and surface heterogeneities similar to Earth, with diurnal rotation, seasonal changes, and weather patterns resulting in complex, time-dependent signatures. Due to its ability to measure light as a vector, polarimetry provides an important tool that will enhance the characterizations of heterogeneous worlds. Here we model the visible to near-infrared linear spectropolarimetric signatures, as functions of wavelength and planetary phase angle, of various heterogeneous Earth scenarios as well as the first signals of an early wet and potentially habitable Mars. The contributions from the different atmospheric and surface properties result in asymmetric phase curves and variable spectra, with the polarization appearing to be more sensitive than flux to heterogeneities such as patchy clouds and continents moving into and out-of-view. Our models provide important predictions of expected polarized and unpolarized signatures of heterogeneous exoplanets that will help guide the designs and observing plans of future polarimeters, including those proposed for the upcoming Habitable Worlds Observatory.

ServiMon is a scalable data collection and auditing pipeline designed for service-oriented, cost-efficient quality control in distributed environments, including the CTAO monitoring, logging, and alarm subsystems. Developed within a Docker-based architecture, it leverages cloud-native technologies and distributed computing principles to enhance system observability and reliability. At its core, ServiMon integrates key technologies such as Prometheus, Grafana, Kafka, and Cassandra. Prometheus serves as the primary engine for real-time performance metric collection, enabling efficient monitoring across multiple nodes. Grafana provides interactive, service-oriented data visualization, facilitating system performance analysis. Additionally, Kafka and Cassandra expose system metrics via the JMX Exporter, offering critical insights into infrastructure availability and performance. This contribution exposes how ServiMon could provide an enhancement on scalability, security, and efficiency in a distributed computing environment, such as the CTAO monitoring, logging, and alarm subsystems. This integrated approach not only ensures robust real-time monitoring, but also optimizes operational costs. Furthermore, ServiMon's ability to generate large volumes of diverse data over time provides a strong foundation for predictive maintenance. By incorporating stochastic and approximate computing techniques, it enables proactive failure detection and system optimization, minimizing downtime and maximizing telescope availability.

Time-variable propagation effects provide a window into the local plasma environments of repeating fast radio burst (FRB) sources. Here we report high-cadence observations of FRB 20240619D, as part of the HyperFlash and ÉCLAT programs. We observed for $500$h and detected $217$ bursts, including $10$ bursts with high fluence ($>25$ Jy ms) and implied energy. We track burst-to-burst variations in dispersion measure (DM) and rotation measure (RM), from which we constrain the parallel magnetic field strength in the source's local environment: $0.32\pm0.19$ mG. Apparent DM variations between sub-bursts in a single bright event are interpreted as coming from plasma lensing or variable emission height. We also identify two distinct scintillation screens along the line of sight, one associated with the Milky Way and the other likely located in the FRB's host galaxy or local environment. Together, these (time-variable) propagation effects reveal that FRB 20240619D is embedded in a dense, turbulent and highly magnetised plasma. The source's environment is more dynamic than that measured for many other (repeating) FRB sources, but less extreme compared to several repeaters that are associated with a compact, persistent radio source. FRB 20240619D's cumulative burst fluence distribution shows a power-law break, with a flat tail at high energies. Along with previous studies, this emphasises a common feature in the burst energy distribution of hyperactive repeaters. Using the break in the burst fluence distribution, we estimate a source redshift of $z=0.042$-$0.240$. We discuss FRB 20240619D's nature in the context of similar studies of other repeating FRBs.

To study and monitor the Sun and its atmosphere, various space missions have been launched in the past decades. With the rapid improvement in technology and different mission requirements, the data products are subject to constant change. However, for long-term studies such as solar variability or multi-instrument investigations, uniform data series are required. In this study, we build on and expand the Instrument-to-Instrument translation (ITI) framework, which provides unpaired image translations. We apply the tool to data from the Extreme Ultraviolet Imager (EUI), specifically the Full Sun Imager (FSI) on Solar Orbiter (SolO) and the Atmospheric Imaging Assembly (AIA) on the Solar Dynamics Observatory (SDO). This approach allows us to create a homogeneous data set that combines the two extreme ultraviolet (EUV) imagers. We demonstrate that ITI is able to provide image calibration between SolO and SDO EUV imagers, independent of the varying orbital position of SolO. The comparison of the intercalibrated light curves derived from EUI and AIA shows that ITI can provide uniform data series that outperform a standard baseline calibration. We evaluate the perceptual similarity in terms of the Fréchet Inception Distance (FID), which demonstrates that ITI achieves a significant improvement of perceptual similarity between EUI and AIA. The study provides intercalibrated observations from SolO/EUI/FSI with SDO/AIA, enabling a homogeneous data set suitable for solar cycle studies and multi viewpoint investigations.

The Energetic Particle Radiation Environment Model (EPREM) solves the focused transport equation (FTE) on a Lagrangian grid in a frame co-moving with the solar wind plasma and simulates the acceleration and transport of solar energetic particles (SEP) in the heliosphere. When not coupled to an external magnetohydrodynamic model, EPREM functions in an uncoupled mode where an ideal cone-shock is injected into a homogeneous background solar wind. We carried out an analysis of the effects of multiple physical parameters in producing widespread SEP events simulated by the uncoupled EPREM using a relatively simple model of a strong magnetized shock propagating radially outward through the inner heliosphere to produce the requisite MHD quantities for EPREM's sophisticated model of proton acceleration and transport. We compared a baseline simulation with seven variations in which the value of a single parameter differed from its baseline value. All simulations exhibit complex profiles of SEP flux as a function of time and energy, with clear dependence on parameters related to diffusion, mean free path, and shock profile. Moreover, while all simulations exhibit significant longitudinal spread in SEP flux, for certain parameter values there exists a decrease or absence in SEP flux at observers located >=90 degrees from the shock origin. Relating the differences in SEP flux to the specific values of each parameter in the simulations provides insight into the morphology of observed SEP events and the state of the solar wind through which the driving CME propagates.

We investigate the evolution of primordial cosmological perturbations in a vacuum decay model where de Sitter space transitions to radiation domination through quantum-thermal decay processes. Unlike standard inflation, this framework generates curvature perturbations through stochastic noise from vacuum decay rather than quantum fluctuations of an inflaton field. We derive the stochastic differential equation governing the curvature perturbation $\mathcal{R}(t)$ and show that any horizon crossing is brief and does not constitute the primary mechanism for perturbation generation. Scale dependence emerges from spatial correlations in the noise rather than horizon crossing dynamics. The model naturally addresses the horizon and flatness problems through initial thermal equilibrium in de Sitter space and predicts zero tensor-to-scalar ratio. We demonstrate that spatially correlated noise can generate observationally viable spectral tilts while maintaining Gaussian statistics.

The Askaryan Radio Array (ARA) is an ultrahigh energy (UHE) neutrino detector at the South Pole, designed to search for radio pulses emitted by neutrino-initiated particle showers in ice. ARA consists of an array of five autonomous stations with 2 km spacing. Each station consists of 16 radio antennas embedded ${\sim}200$ m deep in the ice that are sensitive to either vertically- or horizontally-polarized signals. Radio arrays like ARA represent a cost-efficient means of achieving the enormous detection $O(10~\text{km}^3)$ volumes necessary for UHE neutrino detection. This contribution presents the current status of the first-ever array-wide search for UHE neutrinos, leveraging ARA's unprecedented ${\sim}28$ station-years of livetime. This search will have the best sensitivity of any neutrino detector above $3$ EeV, sufficient to probe the $220$ PeV flux inferred from KM3NeT's observation of KM3-230213A. Importantly, this study demonstrates the feasibility of array-wide neutrino searches, which are necessary for next-generation detectors, like RNO-G (35 stations planned) and IceCube-Gen2 Radio (361 stations proposed), to achieve their design sensitivity. We discuss the progress towards a fully analyzed sample and improvements to ARA's detector characterization and analysis sensitivity.

The Askaryan Radio Array (ARA) is a five-station, in-ice radio detector located at the South Pole searching for particle cascades from cosmogenic and astrophysical neutrinos with $\geq10^{17}$ eV of energy. Cascades in this energy regime emit radio-wavelength Askaryan radiation that can be observed by one or more ARA stations. With the recent KM3Net observation of an approximately $220$ PeV neutrino, there is renewed, urgent interest in further unlocking the ultra-high energy neutrino sky. We present updated calculations of ARA's array-wide effective volume, sensitivity, and expected event rates for ultra-high energy neutrino-induced cascades. Notably, results now account for the contributions of secondary particles from neutrino interactions (such as muon tracks) and multi-station detections within a detailed detector simulation framework. Previous work has shown these secondary interactions and multi-station coincidences compose 25\% and 8\% of the detector's effective area, respectively. We intend to extend these results towards a novel analysis that estimates the degree to which secondary cascades and multi-station observations are detectable in a real neutrino search. This will inform future UHE neutrino searches as it will characterize the feasibility of detecting such events.

Routine measurements of the magnetic field of coronal mass ejections (CMEs) have been a key challenge in solar physics. Making such measurements is important both from a space weather perspective and for understanding the detailed evolution of the CME. In spite of significant efforts and multiple proposed methods, achieving this goal has not been possible to date. Here we report the first possible detection of gyroresonance emission from a CME. Assuming that the emission is happening at the third harmonic, we estimate that the magnetic field strength ranges from 7.9--5.6 G between 4.9-7.5 $R_\odot$. We also demonstrate that this high magnetic field is not the average magnetic field inside the CME, but most probably is related to small magnetic islands, which are also being observed more frequently with the availability of high-resolution and high-quality white-light images.

We present a multiwavelength catalog of mid-infrared-selected compact sources in 19 nearby galaxies, combining JWST NIRCam/MIRI, HST UV-optical broadband, H$\alpha$ narrow-band, and ALMA CO observations. We detect 24,945 compact sources at 21 $\mu$m and 55,581 at 10 $\mu$m. Artificial star tests show 50% completeness limits of $\sim$5 $\mu$Jy for the 10 $\mu$m catalog, and $\sim$24 $\mu$Jy for the 21 $\mu$m catalog. We find that 21 $\mu$m compact sources contribute $\sim$20% of the total galaxy emission in that band, but only contribute $5%$ at 10 $\mu$m. We classify sources using stellar evolution and population synthesis models combined with empirical classifications derived from the this http URL classifications include H$\alpha$-bright and dust-embedded optically faint clusters, red supergiants (RSGs), oxygen-rich and carbon-rich AGB stars, and a range of rarer stellar this http URL sampling a broad range of star forming environments with a uniform, well-characterized selection, this catalog enables enables analyses of infrared-bright stellar populations. We find that H$\alpha$-faint sources account for only 10% of dusty (likely young) clusters, implying that the infrared-bright, optically-faint phase of cluster evolution is short compared to the H$\alpha$-bright stage. The luminosity functions of 10 and 21 $\mu$m sources follow power-law distributions, with the 21 $\mu$m slope ($-1.7 \pm 0.1$) similar to that of giant molecular cloud mass functions and ultraviolet bright star-forming complexes, while the 10 $\mu$m slope ($-2.0 \pm 0.1$) is closer to that of young stellar clusters.

Stellar eruptive events, such as flares and coronal mass ejections (CMEs), can affect planetary habitability by disturbing the stability of their atmospheres. For instance, strong stellar flares and CMEs can trigger atmospheric escape and, in extreme cases, may strip away the atmosphere completely. While stellar flares have been observed and explored at a wide range of wavelengths, the physical properties of stellar CMEs remain unconstrained due to the difficulty in observing them. In this context, the Sun provides our only window on the potential characteristics of CMEs on Sun-like stars. A correlation between solar X-ray flare peak flux and the mass of flare-associated solar CMEs has been reported using solar data collected during Solar Cycle 23 (1996-2006) (Aarnio et al. 2011). Here, we build upon that work. We extend the correlation into the far-UV (FUV), where stellar flares are and will be routinely detected with existing and future FUV observatories by incorporating data spanning two entire Solar Cycles (23 and 24; 1996-2019). Using three different space missions (CMEs from LASCO/SOHO, X-ray flare events from XRS/GOES, and FUV flares from AIA/SDO), we report a correlation between FUV flare peak flux and energy centered at 1600Å and mass, kinetic energy, and linear speed of flare-associated CMEs. These empirical relations enable estimates of CME masses and kinetic energies from FUV flares on Sun-like stars. While direct stellar-CME detections remain elusive, the correlations derived here are likely applicable to Sun-like stars and provide a working framework for evaluating exoplanet atmospheric erosion.

The impact of energy exchange among the relevant fluid components: baryonic matter, fermionic dark matter (DM), and dark energy (DE) on the internal structure of neutron stars is investigated. Using a representative DM mass $m_{\chi} = 10$ GeV and a barotropic DE relation, we add source terms Qi to the Tolman-Oppenheimer-Volkoff equations and examine three cases: (i) noninteracting fluids (Model I), (ii) fully interacting baryon plus DM and DM with DE fluids with optional DM self repulsion (Model II), and (iii) a unified dark sector coupled to baryons (Model III). Two effects dominate: softening by massive, pressure-poor DM, and additional softening/ and binding from DE with negative pressures. Model I isolates these baselines. In Model II, exchange terms self regulate, making the mass radius curves nearly independent of the coupling parameter $\alpha$ for nearly five orders of magnitude. Model III breaks this $\alpha$ degeneracy: a sizable vacuum fraction suppresses the baryonic pressure gradient, reducing both the maximum mass and radii, whereas a pure-DM core is less sensitive. We outline when dark interactions can leave observable, macroscopic imprints.

We report the discovery of a new subclass of carbon-enhanced metal-poor (CEMP) stars, characterized by high absolute carbon abundances (A(C) > 7.39) and extremely low metallicity ([Fe/H] $<=$ -3.1) but notably lacking enhancements in neutron-capture elements, thus falling under the CEMP-no category. This population emerged from a detailed analysis of low-resolution spectroscopic data obtained from the Sloan Digital Sky Survey (SDSS) and the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST), where the observed frequency trends with the decreasing metallicity of CEMP-s (s-process-enhanced) and CEMP-no (no neutron-capture enhanced) stars deviated from established expectations. In contrast to earlier findings, we observe a rise in high-A(C) stars below [Fe/H] = -3.1, which we interpret as a distinct group not accounted for in traditional CEMP classifications. Following the Yoon-Beers group classification, we define these stars as Group IV. Statistical modeling confirms their presence as a separate peak in the A(C) distribution, and available radial velocity data suggest that about 30% of Group IV stars may be binaries, indicating possible binary-related formation mechanisms. This discovery challenges the current CEMP-no star formation pathways and implies the existence of alternative or hybrid enrichment scenarios in the early Universe. High-resolution spectroscopic follow-up of Group IV candidates will be crucial for identifying their progenitors and understanding their evolutionary implications.

Galaxies with high star-formation rate surface densities often host large-scale outflows that redistribute energy, momentum, and baryons between the interstellar medium and the halo, making them a key feedback channel regulating galaxy evolution. Despite their importance, the driving physics behind galactic outflows and their interaction with the surrounding halo is yet to be fully understood. In particular, the influence of a pre-existing reservoir of cosmic rays (CRs) in galaxy halos has not been clearly established. We determine the conditions required to launch outflows in the presence of halo CRs and investigate how CR pressure gradients modify outflow speeds. We find that CR halos suppress the development of large-scale, CR-driven winds and redirect CR feedback toward local recycling flows. Slow outflows are therefore more likely in young galaxies lacking extended CR halos, while fast winds in intense starbursts are dominated by momentum injection and largely unaffected by halo CRs.

Tidal disruption events (TDEs) are believed to be an ideal laboratory for studying the evolution of accretion flow around a supermassive black hole (BH). In general, the mass feeding rate to the BH is suggested to be super-Eddington initially, and evolves to be sub-Eddington on timescale of years. In this paper, we carry out calculations of the time-dependent evolution of accretion disk in the standard environment of TDE, i.e., injecting matter at the circularization radius of the stellar debris in the form of $\dot M_{\rm inject} \propto t^{-5/3}$. One of the main findings is that when $\dot M_{\rm inject}$ evolves to a value around the Eddington accretion rate, the radiation pressure instability occurs. We test the influence of the model parameters on the light curves, such as the BH mass $M_{\rm BH}$, viscosity parameter $\alpha$, and mass-injecting radius $R_{\rm{out}}$, all of which are found to affect the light curves to some extent. In most cases, we find that the light curves oscillate significantly due to the radiation pressure instability. As an exception, when $\alpha$ is small or $R_{\rm{out}}$ is large, we find that the oscillations are completely suppressed. In this case, the light curve drops steeply and then becomes flat in the late-time evolution, which is applied to explaining the observed ultraviolet (UV) light curves of ASASSN-15oi and ASASSN-14ae together with the assumption of a photosphere. Finally, we discuss the potential applications of our time-dependent accretion disk model to explaining multi-band light curves of TDEs in the future.

Theoretical and experimental foundations of the hypothesis about the origin of the magnetic fields of the Earth and other astrophysical objects, proposed in the early 20th century by W. Sutherland, A. Einstein, and independently by Yu.S. Vladimirov, are discussed in the paper. According to this hypothesis, the electric charges of the electron and proton slightly differ in magnitude, leading to the emergence of a magnetic field in rotating astrophysical objects. The theoretical justification of the Sutherland-Einstein hypothesis is presented in a simplified version of the 6D Kaluza-Klein theory, taking into account the consequences of the Kerr-Newman metric. The analysis shows that a fundamental dipole-type magnetic field should arise around any massive rotating body. However, in real astrophysical objects, such a field is largely screened and distorted by induced charges and currents. As an application, we consider the problem of determining the magnetic fields of hot Jupiters, since the strong tidal effects in these giant exoplanets should result in approximately similar screening mechanisms.

We present GDCluster, a fully automated algorithm for decomposing spectral-line datacube of interstellar gas into coherent structures. Assuming a multi-Gaussian nature of observed spectra, GDCluster employs and augments the derivative spectroscopy technique for precise parameter estimation, incorporates spatial-continuity constraints during spectral fitting, and extends these constraints to spatial clustering. This approach effectively resolves velocity blending structures in PPV space-particularly critical for ubiquitous HI spectra where emissions from multiple phases are severely blended. Applied to the all-sky HI4PI data, a 10 degree times 10 degree CRAFTS survey region, and a 45 degree times 10 degree MWISP survey region, GDCluster extracts 45,299, 2247, and 47,119 structures in HI and CO (1-0), respectively. Comparative analyses demonstrate GDCluster's superiority over DBSCAN in separating overlapping spectra with complex velocity components.

Accreting black holes are thought to swallow matter in the form of a disk and a hot cloud of plasma that glows brightly in X-rays, known as the corona. The X-ray emitting region is far too small to be directly imaged, but rapid variability of the X-ray signal can be used to infer the geometry by measuring time lags caused by material propagating towards the black hole and by coronal X-rays reflecting off the disk to imprint a reverberation lag. Reverberation lags can be recognized by characteristic spectral features, including an iron emission line at $\sim 6.4$ keV and a broad Compton hump peaking at $\sim 30$ keV. These reverberation features have both previously been detected for a few supermassive black holes in active galactic nuclei (AGNs). However, it is much more challenging to detect reverberation lags from stellar-mass black holes because they are more than a million times smaller. Previous reverberation lag measurements for stellar-mass black holes in X-ray binary systems have thus been limited to energies below 10 keV. Here we report on the first detection of the Compton hump reverberation feature from an X-ray binary, achieved by measuring lags in the broad energy range of $\sim 1-150$ keV. The accompanying detection of an iron line feature confirms the scenario of X-ray reverberation and provides strong evidence that the accretion flows in AGNs and X-ray binaries are governed by an ubiquitous process. Reverberation lags are prominent only in the most rapid variability, whereas lags in the slower variability are commonly attributed to propagating mass accretion rate perturbations. Our lag measurements up to the highest energy to date reveal that this lag in the slower variability evolves dramatically on timescales of days.

We present a multi-frequency study of the bent-tail radio galaxy J1051+5523, located in the galaxy cluster WHL J105147.4+552309. This wide-angle tail (WAT) galaxy exhibits a complex radio morphology, characterised by a right-angled bend in the northern jet, which resembles an axe, and multiple kinks in the southern jet, as observed in the deep uGMRT radio observations. The radio power of J1051+5523 at 150 MHz is estimated to be $2.91 \times 10^{25}\,\mathrm{W\,Hz^{-1}}$, placing it in the transition zone between FRI and FRII radio galaxies. The spectral index map reveals a flat core and relatively flat lobes, which may indicate ongoing particle acceleration or a relatively young population of relativistic electrons in the lobes. Further, we estimate the equipartition magnetic fields, and spectral ages of the northern and southern lobes to be approximately 150 Myr and 153 Myr, respectively, suggesting a long-lived radio source with sustained AGN activity. A relative velocity of 278 $\pm$ 2643 $\mathrm{km\,s^{-1}}$ is obtained for the host galaxy. Due to the large uncertainty associated with the relative velocity estimates, the contribution of ram pressure to the jet bending remains inconclusive. The low mass of the host cluster ($\sim 2 \times 10^{14}\,M_\odot$) and the lack of diffuse X-ray emission indicate a reduced likelihood of major mergers, but minor mergers or interactions remain possible. We propose that the observed WAT morphology of J1051+5523 is likely shaped by a combination of ram pressure and/or buoyant forces within the cluster environment.

The Zirè experiment onboard NUSES space mission has several science goals, including the measurements of charged particles and light nuclei from few up to hundreds of MeVs, for the study of low-energy cosmic rays, space weather phenomena, and possible magnetosphere-lithosphere-ionosphere coupling signals. Furthermore, the experiment intends to test new tools for the detection of photons in the energy range of about 0.03-50 MeV, allowing the investigation of transient phenomena like gamma-ray bursts (GRBs). A high-density segmented calorimeter exploiting novel scintillator crystals and silicon photomultiplier technology for the readout system will serve this purpose along its main task of calorimetric energy measurement of the cosmic-ray charged particles. In this work, we discuss the functionality of the calorimeter as a GRB monitor through the calculation of its performance in terms of effective area, sensitivity, and timing response for the transient outbursts.

\omega}Centauri ({\omega}Cen) is the most enigmatic Galactic globular cluster (GC), with unmatched chemical complexity. We combine photometric and spectroscopic catalogs to identify its distinct stellar populations and to investigate their spatial distribution and chemical properties, uncovering new insights into the cluster's formation history. We identify the iron-poor stars commonly found in GCs: the first population (1P), with halo-like chemical composition, and the second population (2P), enriched in elements produced by p-capture processes. Similarly, we divided the iron-rich stars (the anomalous stars) into two groups: the AI and the AII, exhibiting light-element abundance distributions similar to 1P and 2P stars, respectively. The wide extension of our dataset (five times the half-light radius) allowed us to directly and unambiguously compare the fraction of these populations at different radii. We find that 2P and AII stars are more centrally concentrated than the 1P and AI. The remarkable similarities between the 1P-2P and AI-AII radial distributions strongly suggest that these two groups of stars originated from similar mechanisms. Our chemical analysis indicates that the 1P and AI stars (the lower stream) developed their inhomogeneities through core-collapse supernova (and possibly other massive stars') self-enrichment, and that these populations contributed p-capture-processed material to the intracluster medium, from which the chemically extreme 2P and AII stars (the upper stream) formed. Additional polluters, such as intermediate-mass asymptotic giant branch stars and Type Ia supernovae, likely played a role in shaping the AII. Finally, we propose that 2P and AII stars with intermediate light-element abundances (the middle stream) formed via dilution between the pure ejecta that created the upper stream and lower-stream material.

The source count dipole from wide-area radio continuum surveys allows us to test the cosmological standard model. Many radio sources have multiple components, which can cause an overdispersion of the source counts distribution. We account for this effect via a new Bayesian estimator, based on the negative binomial distribution. Combining the two best understood wide-area surveys, NVSS and RACS-low, and the deepest wide-area survey, LoTSS-DR2, we find that the source count dipole exceeds its expected value as the kinematic dipole amplitude from standard cosmology by a factor of $3.67 \pm 0.49$ -- a $5.4\sigma$ discrepancy.

We analyze the inner debris disk around $\epsilon$ Eridani using simulated observations with the Cool-Planet Imaging Coronagraph (CPI-C). Using the radiative transfer code MCFOST, we generate synthetic scattered-light images and spectral energy distributions for three disk models that differ in inclination and radial extent, and compare these results with the anticipated performance of CPI-C. CPI-C can resolve disk structures down to $\sim$3 au, offering substantially finer spatial resolution than existing HST/STIS and Spitzer/IRS observations. Recovered inclinations and radial extents closely match the input models, constraining the disk geometry and informing potential planet-disk interactions in the $\epsilon$ Eri system. Although the cold Jupiter-like planet $\epsilon$ Eri b is not detected in our simulations, polarimetric methods may enable detection of its reflected light. These results highlight the capability of next-generation coronagraphs to probe cold dust in nearby planetary systems.

Stellar-mass binary black hole (BBH) mergers occurring within the disks of active galactic nuclei (AGN) are promising sources for gravitational waves detectable by the LIGO, Virgo, and KAGRA (LVK) interferometers. Some of these events have also been potentially associated with transient electromagnetic flares, indicating that BBH mergers in dense environments may be promising sources of multi-messenger signals. To investigate the prospects for electromagnetic emission from these systems, we study the dynamics of accretion flows onto BBHs embedded in AGN disks using numerical simulations. Although recent studies have explored this scenario, they often employ simplified disk models that neglect magnetic fields. In this work, we examine how strong magnetic fields influence and regulate the accretion onto such binary systems. In this context, we conduct three-dimensional magnetohydrodynamical local shearing-box simulations of a binary black hole system embedded within a magnetized disk of an AGN. We observe that the dynamically important magnetic fields can drive the formation of well-collimated outflows capable of penetrating the vertical extent of the AGN disk. However, outflow generation is not ubiquitous and strongly depends on the radial distance of the binary from the supermassive black hole (SMBH). In particular, binaries placed at a larger distance from the central SMBH show relatively more transient accretion and the formation of stronger spiral shocks. Furthermore, accretion behavior onto the binary system via individual circum-singular disks (CSDs) is also modulated by local AGN disk properties. Our simulations highlight the importance of shear velocity in the amplification of the toroidal magnetic field component, which plays a crucial role in governing the outflow strength.

In this article, we present the results of an analysis of chemical abundances and a search for magnetic fields in eight field blue horizontal-branch (BHB) stars: BD\,+01$^{\circ}$0548, HD\,74721, HD\,86986, HD\,87112, HD\,93329, HD\,109995, HD\,161817, and HD\,167105. This study is based on high-resolution optical spectra obtained with ESPaDOnS at the Canada-France-Hawaii Telescope. We first calculated the average chemical element abundance, the rotational velocity, and the radial velocity of the stars using the ZEEMAN2 spectrum synthesis code with the PHOENIX model atmospheres. We then studied the abundances of titanium and iron inferred from individual lines in the spectra of each star and their variations with their predicted formation depths $\tau_{\rm 5000}$. Similarly to the BHB stars cooler than 11500~K observed in globular clusters, no clear observational evidence of vertical stratification is detected in the atmosphere of these stars. In the second part of this project, we searched for the presence of a magnetic field in the stars applying the Least-Squares Deconvolution technique on the Stokes $I$ and $V$ spectra. The measured mean longitudinal magnetic field uncertainties, ranging from 8 to 30~G, effectively rule out the presence of an organized magnetic field in these targets with a strength larger than a few 100~G.

Astronomers are debating whether the plentiful "sub-Neptune" exoplanets -- worlds a bit larger than Earth but smaller than Neptune -- are predominantly rocky planets, water-rich "ocean worlds," or gas-enshrouded mini-Neptunes. This question is crucial because such sub-Neptune-sized planets are among the most common in our galaxy, yet we have no analog in our own solar system, making them a key to understanding planet formation and diversity. It also directly impacts the search for habitable worlds: larger-than-Earth planets with solid surfaces or oceans could support life, whereas gas-rich mini-Neptunes likely cannot. However, distinguishing these types using only a planet's mass and radius is very challenging, because different compositions can produce similar densities, leaving a world's nature ambiguous with current data. The proposed Habitable Worlds Observatory (HWO), a future NASA flagship telescope, offers a solution. HWO could directly image and spectroscopically analyze starlight reflected from 50~100 sub-Neptunes around nearby stars, aiming to reveal their atmospheric compositions and potential surfaces. Using visible and near-infrared spectroscopy along with sensitive polarimetry, HWO would detect atmospheric gases (such as water vapor, methane, and carbon dioxide) and search for telltale surface signatures, including rock absorption features and the characteristic reflectivity patterns of oceans. By analyzing these signals, we could determine whether sub-Neptunes are large rocky planets or water worlds rather than gas-dominated mini-Neptunes. Crucially, expanding the search beyond Earth-sized planets to include these abundant sub-Neptunes may uncover entirely new classes of potentially habitable worlds, directly advancing HWO's mission to identify and characterize planets that could support life.

Multiple populations, defined by correlations between light element abundances, are an almost ubiquitous property of globular clusters. On the other hand, dispersions among the heavy elements are limited to a few rare clusters. In this letter, we present Mg, Y, Ba, La, and Eu measurements for 89 stars in M15 with errors < 0.4 dex from Keck/DEIMOS medium-resolution spectra. We find higher Ba, La, and Eu dispersions in the first generation of stars than in the second generation at a significance of $\ge$2 $\sigma$. This is evidence for inhomogeneous mixing of gas during the formation of the first generation of stars, which subsequently became well-mixed prior to the formation of the second generation of stars. If the r-process event that caused the abundance dispersions was born with the first population of stars, it must be an r-process site with a short delay time.

This study refines the Greisen formalism by comparing the classical Greisen profile and a modified Greisen profile, which incorporates an empirical correction to the shower age parameter with zenith-angle dependence, aiming to better describe low-energy cascades against CORSIKA simulations of cosmic gamma-ray showers (20-800 GeV). Fittings across altitudes of 5000-5900 m and zenith angles from 0 to 40 degrees quantify deviations in particle numbers, showing that the modified profile yields deviations below 4.7%, compared to up to 12.5% for the classical profile. These improvements address low-energy ionization losses, atmospheric density variations, and zenith-angle effects, enhancing accuracy for high-altitude observatories like HAWC and the proposed CONDOR array. The modified profile offers a computationally efficient alternative, providing precise particle number predictions to advance gamma-ray astrophysics and cosmic-ray research.

Understanding the relationship between magnetic flux ropes and magnetic reconnection is fundamental to both space and astrophysical plasma studies. In this study, we report on two consecutive heliospheric current sheet (HCS) crossings by Parker Solar Probe (PSP), separated by ~10.5 hours, at a heliocentric distance of ~12 solar radii. For each crossing, we identified a series of flux ropes embedded within reconnection exhausts on the sunward side of X-line. Their passage durations are <20sec, corresponding to spatial scales of a few thousands kilometers, still larger by three orders of magnitude than ion inertial length. This identification was possible particularly during intervals when PSP was closest to the HCS center. These flux ropes are distinguishable from the background exhausts by enhancements in magnetic field strength, significantly in the guide field component, travel speed slightly faster (typically by <10km/s) than surrounding outflows, and often accompanied by, though not always, increased density and reduced temperature. We attribute their origin to secondary reconnection within the exhausts and subsequent merging of smaller flux ropes into larger structures, consistent with predictions by various simulations. We suggest that such flux ropes are most readily identifiable at the HCS center where the background magnetic field is weakest so that the relative enhancement in flux rope field becomes most prominent. This observational advantage is particularly notable closer to the Sun where the high ambient magnetic field strength can otherwise obscure such structures unless the spacecraft trajectory remains within the HCS central region for a sufficient duration.

We report deep long-slit spectroscopy of two Galactic compact planetary nebulae (PNe), PNG048.5+04.2 and PNG068.7+14.8, obtained using the 10.4m Gran Telescopio Canarias (GTC). These spectra cover a broad wavelength range of ~3630-10370 A, enabling detection of numerous emission lines critical for nebular analysis, including [O II] 3727 and [O III] 4363 in the blue and [S III] 6312,9069 in the red. Also detected in the spectrum of PNG068.7+14.8 are broad C III and C IV lines probably due to stellar emission, indicating that the central star of this PN is [WC]-type. These GTC optical-IR spectra were analyzed in details in conjunction with the archival Spitzer/IRS mid-IR spectra, and elemental abundances of the two PNe determined. Photoionization models were established for the two PNe using CLOUDY, based on the ratios of line fluxes measured from the GTC optical-NIR spectra. Our best photoionization modeling, in combination with state-of-the-art post-AGB evolutionary model tracks, shows that both PNe evolved from low-mass progenitors (<2 M_sun) with relatively young ages (<3 Gyr), although their central cores are probably in different evolutionary stages - the central star of PNG068.7+14.8 is still in the process of heating up, while that of PNG048.5+04.2 has already entered the white dwarf cooling track. A comparison with AGB model predictions also constrains the progenitors of both PNe to be of low masses. Moreover, the two PNe are in line with the radial oxygen gradients exhibited by the Galactic PN populations, using the most up-to-date distances.

The reverberation mapping (RM) is the most promising method to measure the mass of supermassive black hole in the center of active galaxy nuclei (AGNs). However, the dominant jet component hinders the application of RM method for blazars. In this work, we present a new algorithm to disentangle the contributions of the accretion disk and relativistic jet in blazars by analyzing the optical spectroscopic data. Applying this method to two flat-spectrum radio quasars, PKS 1510-089 and PKS 0736+017, we find that the H$\gamma$ variability in PKS 1510-089 lags behind the disk by approximately 116 days, while the H$\beta$ line exhibits a lag of about 52 days relative to the disk in PKS 0736+017. Based on these measured time lags, we estimate that the black hole masses are about $1.8 \times 10^8\ M_\odot$ for PKS 1510-089 and about $7.0 \times 10^7\ M_\odot$ for PKS 0736+017, respectively. This method paves the way to apply the RM method for blazars, and improves the understanding of disk and jet activities.

We present spatially resolved Keck/NIRC2 images of a stellar occultation by Titan on September 5, 2022 and compare them to predictions from concurrent ALMA observations and a suite of General Circulation Model (GCM) simulations. ALMA data and GCM simulations can predict middle atmosphere zonal wind distributions, which in turn produce diagnostic occultation image sequences. We construct an occultation forward model using the temperature profile measured by the Huygens Atmospheric Structure Instrument, which is then distorted using latitudinal zonal wind profiles from the ALMA data or GCM simulations. The occultation forward model yields simulated light distributions around Titan's limb, which we compare directly to the light distributions observed during the occultation. The GCM zonal wind profile corresponding to slightly before the time of the stellar occultation provides the best overall match to the data. The ALMA wind profile provides the best match to the occultation data when only the ingress data were considered, but is not the best match when data from ingress and egress are combined. Our data support the presence of stronger winds in the southern hemisphere during late northern summer.

The ${}^{12} \mathrm{C}(\alpha, \gamma)^{16} \mathrm{O}$ reaction is one of the most important reactions in the evolution of massive stars, yet its rate is still highly uncertain. In this work, we investigated how variations in the ${}^{12} \mathrm{C}(\alpha, \gamma)^{16} \mathrm{O}$ reaction rate affect the evolution of a 14 $\rm M_{\odot}$ He star using the MESA code. Our simulations indicate that the ${}^{12} \mathrm{C}(\alpha, \gamma)^{16} \mathrm{O}$ reaction rate determines the conditions for C burning, affecting its explodability. As the reaction rate increases, central C-burning becomes neutrino-dominated, transitioning from the convective to the radiative regime. This leads to higher compactness and a larger iron core, indicating a more compact pre-SN core structure that is difficult to explode. Conversely, lower reaction rates shorten the C-burning lifetime and trigger earlier central Ne ignition, which counteracts core contraction. This results in reduced compactness and iron core mass. We also found that variations in reaction rates shift the location of the last C-burning shell. When this shell exceeds the mass coordinate used for compactness evaluation, the overall compactness increases significantly. Although the Si- and O-burning convective shells decrease compactness, the overall increase remains unaffected. This work suggests that the ${}^{12} \mathrm{C}(\alpha, \gamma)^{16} \mathrm{O}$ reaction play an important role in the pre-SN core structure and potentially impact the explodability of massive He stars.

A galaxy's mid-IR spectrum encodes key information on its radiation field, star formation, and dust properties. Characterizing this spectrum therefore offers strong constraints on a galaxy's activity. This project describes a diagnostic tool for identifying main-sequence (MS) star-forming galaxies (SFGs) in the local Universe using IR dust emission features that are characteristic of galaxy activity. A physically-motivated sample of mock galaxy spectra has been generated to simulate the IR emission of SFGs. Using this sample, we developed a diagnostic tool for identifying MS SFGs based on machine learning methods. Custom photometric bands were defined to target dust emission features, including polycyclic aromatic hydrocarbons (PAHs) and the dust continuum. Three bands were chosen to trace PAH features at 6.2 {\mu}m, 7.7 {\mu}m, 8.6 {\mu}m, and 11.3 {\mu}m, along with an additional band to probe the radiation field strength responsible for heating the dust. This diagnostic was subsequently applied to observed galaxies to evaluate its effectiveness in real-world applications. Our diagnostic achieves high performance, with an accuracy of 90.9% on MS SFGs (observed sample of SFGs). Additionally, it shows low contamination, with only 16.2% of AGN galaxies being misidentified as SF. Combining observational data with stellar population synthesis models enables the creation of physically-motivated samples of SFGs that match the spectral properties of real galaxies. By positioning custom photometric bands targeting key dust features, our diagnostic can extract valuable information without the need to measure emission lines. Although PAHs are sensitive indicators of star formation and interstellar medium radiation hardness, PAH emission alone is insufficient for identifying MS SFGs. Finally, we developed a physically-motivated spectral library of MS SFGs spanning from UV to FIR wavelengths.

X-ray polarization measurable with the imaging X-ray Polarimetry Explorer (\textit{IXPE}) could constrain the long-debated leptonic versus hadronic origin of the high-energy component in the broadband spectral energy distribution (SED) of blazars. We report \textit{IXPE} results and SED modeling of PKS 2155$-$304 and 3C 454.3, a high- and low-synchrotron-peaked blazar. For PKS 2155$-$304, model-independent analysis gives polarization angle $\Psi_X$ = (130$\pm$2.5) deg and polarization degree $\Pi_X$ = (20.9$\pm$1.8)\% in the 2$-$8 keV band, in agreement with spectro-polarimetric analysis. We found $\Pi_X$ varies with time and shows indications of energy dependence, suggesting stratified emission regions. For 3C 454.3, no X-ray polarization is detected in the June 2023 observation, analyzed here for the first time. The detection in PKS 2155$-$304 and non-detection in 3C 454.3 are consistent with X-ray emission from synchrotron and inverse Compton processes, respectively. Dividing the dataset into finer time bins allows a more granular view of polarization variability. We modeled the broadband SEDs using quasi-simultaneous optical, UV, and X-ray data from {\it Swift}, {\it AstroSat}, and $\gamma$-rays from {\it Fermi}. In PKS 2155$-$304, X-rays lie in the high-energy tail of the synchrotron component, while in 3C 454.3 they lie in the rising part of the inverse Compton component. Our SED modeling with X-ray polarization favors a leptonic scenario for PKS 2155$-$304. These results support a structured jet model where X-ray emission originates from a compact acceleration zone near the shock front, while lower-energy optical emission comes from a broader turbulent region.

The interaction of carbon atoms with solid carbon monoxide (CO) is a fundamental process in astrochemistry, influencing the formation of complex organic molecules in interstellar environments. This study investigates the adsorption and reaction mechanisms of carbon atoms on solid CO under cryogenic conditions, employing a combination of experimental techniques, including photostimulated desorption and resonance-enhanced multiphoton ionization (PSD-REMPI) and infrared spectroscopy, alongside quantum chemical calculations. The results reveal the formation of oxygenated carbon chains, such as CCO, C$_3$O$_2$, and C$_5$O$_2$, as well as CO$_2$. The findings highlight the role of chemisorption and subsequent reactions in driving molecular complexity on solid CO, with implications for the chemical evolution of interstellar ices and the potential formation of prebiotic molecules.

Space-borne gravitational wave detections raise new questions for heliophysics: how the Sun-Terrestrial space environment affect gravitational wave detection, and to what extent? Space-borne gravitational wave detectors use laser interferometry to measure displacement variations between two free test masses caused by gravitational waves. Space-borne gravitational wave detectors require extremely high measurement accuracy, making it necessary to take into account the effects of space plasma and magnetic field. On one hand, laser propagation through space plasma can induce optical path difference noise, affecting distance measurement accuracy. On the other hand, interactions between space magnetic field and the test masses can generate acceleration noise. This review introduces studies on laser propagation noise and space magnetic acceleration noise in space gravitational wave detection. And this review presents a method, time-delay interferometry, to suppress laser propagation noise.

We numerically study fast Newtonian radiation mediated shocks (RMS - v/c~0.2) in two simplified problems in the context of supernova shock breakout; (1) An RMS traveling in a uniform medium, and (2) an RMS escaping a powerlaw density profile in planar geometry (\rho~x^n). Both problems were previously solved in the literature assuming a fully ionized plasma medium emitting Bremstrahllung. It was shown that at high shock velocities photons can deviate from local thermal equilibrium (LTE) and reach distributions peaked at many keV. In this study we incorporate, for the first time, opacity from bound species of heavy elements (solar-like composition) into these two problems, at times drastically augmenting the photon production due to bound-free and bound-bound radiative processes. We use a previously developed hydrodynamically coupled multi-group radiative diffusion code, including inelastic Compton scattering and frequency-dependent opacity from the publicly available TOPS table. Adding a more realistic opacity leads the radiation to maintain LTE at higher velocities in comparison to the fully ionized problem. In the planar SBO problem this opacity can reduce the emission temperature by half and even an order of magnitude. This result is important for the observation of supernova shock breakout emission. The SED of SN envelope breakout will very likely remain in LTE for explosions in red super giant stars without stellar wind (and part of blue super giant star explosions), making X-Ray observations less likely in these cases by orders of magnitude relative to previous predictions. We provide a semi-analytic description for the SED in the case where LTE is maintained. A correct shock-breakout calculation requires opacity tables that include bound yet highly ionized species, ruling out the use of certain line tables (such as the commonly used Kurucz table).

In astrophysics, line opacity is a primary source of uncertainty in theoretical calculations of radiative transfer. Much of this uncertainty is dominated by the inability to resolve the width and separation in frequency of sharp atomic transition lines, leading to the common use of approximate frequency-averaged treatments for the lines. In a previous paper, we calculated shock-cooling emission following explosions in core-collapse supernovae using a mult-group radiative transfer code, and compared the results to those of the similar and often used STELLA code from the literature. We found important differences in the spectral energy distribution (SED) resulting from different choices of line opacity treatment. In our code, we used in the emissivity a frequency-binned average of a high-resolution opacity, while in STELLA the often-used Eastman Pinto 1993 (EP93) prescription was employed. In this short letter we revisit this comparison, essentially reproducing STELLA bound-free (photoionization) and bound-bound (line transition) opacities. We show the importance of introducing micro-plasma electron excitation level cutoffs in the equation of state (EOS). We also argue that EP93 is useful for estimating photon mean free-path in the presence of a forest of lines, but that it can underestimate photon production and reprocessing rates (emissivity) by orders of magnitude. To our knowledge, no fully-consistent coarse-frequency solution currently exists for line modeling in these systems. Finally, we describe new features in our updated publicly available high-resolution frequency-dependent opacity table.

We report the discovery of a new short-period pre-main-sequence eclipsing binary, RX Gru, orbited by a distant circumbinary companion. We characterized the system by analysing the photometric observations from the Solaris network, the Transiting Exoplanet Survey Satellite, and the Super Wide Angle Search for Planets survey, combined with the radial velocities from four high-resolution spectrographs: HARPS, FEROS, CHIRON, and HRS. We derived the parameters of the eclipsing components, which are $M_{\rm Aa} = 1.004^{+0.027}_{-0.026}\,$M$_\odot$, $R_{\rm Aa} = 1.007\pm0.021\,$R$_\odot$, and $T_{\rm eff,Aa} = 5379\pm289\,$K for the primary, and $M_{\rm Ab} = 0.985^{+0.024}_{-0.025}\,$M$_\odot$, $R_{\rm Ab} = 1.024\pm0.023\,$R$_\odot$, and $T_{\rm eff,Ab} = 5322\pm278\,$K for the secondary. We determined the age of the system from the observed parameters using two evolution codes, MESA and Cesam2k20. We obtained an age of $\sim$28$\,$Myr, placing the two stars at the very end of the pre-main-sequence phase. We also derived the minimum mass and orbital period of the tertiary companion, which are found to be $M_{\rm B} = 89.0\pm3.5\,$M$_{\rm Jup}$ and $P_{\rm AB} = 23.79 ^{+0.10 }_{-0.25}\,$yr, respectively. We conclude that RX Gru consists of a tight inner binary composed of two twin components and an outer low-mass companion (a massive brown dwarf or a very low-mass star) in a relatively wide orbit, and we suggest that the system was formed via the dynamical unfolding mechanism coupled with the shared accretion of the circumbinary material by the binary components.

Hot subdwarfs with close low-mass M-type or brown dwarf companions usually show the reflection effect and often also eclipses. Through inspecting the light variations, we estimate the fractions of reflection effect systems detected in different subclasses of hot subdwarfs and constrain their possible formation channels. We noticed that none of the helium-rich hot subdwarfs were found with the reflection effect. Most of them might form through the merger channel. About 13\% of the He-poor hot subdwarfs on the extreme horizontal branch (EHB) with $T_{\rm eff}$ $\sim$ 25,000 -- 33,000 K are discovered with the reflection effect. Nevertheless, the cooler hot subdwarfs located on the top of the EHB, those grouped on the bottom of the EHB, and those located above the EHB with $T_{\rm eff}$ $\sim$ 45,000 -- 75,000 K exhibit lower fractions of reflection effect systems of about 2\%. These three subclasses of hot subdwarfs might contain higher fractions of single stars. Hot subdwarfs below the EHB also show a low fraction of reflection effect systems. They might have a higher fraction of stars with close WD companions. A similar fraction of reflection effect systems to those on the EHB with $T_{\rm eff}$ $\sim$ 25,000 -- 33,000 K is found in hot subdwarfs located above the EHB with $T_{\rm eff}$ $\sim$ 35,000 -- 45,000 K. We also discovered that hot subdwarfs close to the Galactic Plane might have a higher fraction of stars with the reflection effect than those at higher latitudes.

Wide-separation lensed quasars (WSLQs) are a rare subclass of strongly lensed quasars produced by massive galaxy clusters. They provide valuable probes of dark-matter halos and quasar host galaxies. However, only about ten WSLQ systems are currently known, which limits further studies. To enlarge the sample from wide-area surveys, we developed a catalog-based pipeline and applied it to the CatNorth database, a catalog of quasar candidates constructed from Gaia DR3. CatNorth contains 1,545,514 quasar candidates with about 90% purity and a Gaia G-band limiting magnitude of roughly 21. The pipeline has three stages. First, we identify groups with separations between 10 and 72 arcsec using a HEALPix grid with 25.6 arcsec spacing and a friends-of-friends search. We then filter by intra-group color and spectral similarity, reducing the 1,545,514 sources to 14,244 groups while retaining all known, discoverable WSLQs. Finally, a visual check, guided by image geometry and the presence of likely foreground lenses, yields the candidate list with quality labels. We identify 333 new WSLQ candidates with separations from 10 to 56.8 arcsec. Using available SDSS DR16 and DESI DR1 spectroscopy, we uncover two new candidate systems; the remaining 331 candidates lack sufficient spectra and are labeled as 45 grade A, 98 grade B, and 188 grade C. We also compile 29 confirmed dual quasars as a by-product. When feasible, we plan follow-up spectroscopy and deeper imaging to confirm WSLQs among these candidates and enable the related science.

The $^{12}\mathrm{C}(\alpha,\gamma)^{16}\mathrm{O}$ reaction governs the carbon-to-oxygen ratio set during helium burning, shaping white-dwarf structure and Type~Ia supernova yields. At the astrophysical energy $E \approx 300~\mathrm{keV}$, the cross section is controlled by the subthreshold $1^{-}$ (7.12~MeV) and $2^{+}$ (6.92~MeV) states, whose contributions depend on their asymptotic normalization coefficients (ANCs) $C_{1}$ and $C_{2}$, respectively. We perform a Bayesian analysis of the $S_{E1}(300~\mathrm{keV})$ and $S_{E2}(300~\mathrm{keV})$ factors using calibrated $R$-matrix mappings and experimental ANC constraints for the $1^{-}$, $2^{+}$, and $0^{+}$ ground state. For $S_{E1}(300~\mathrm{keV})$, flat prior on the $1^{-}$ ANC lead to broad posterior with $68\%$ credible interval spanning $ [71.4,\,93.4]$~keV\,b, while Gaussian priors concentrate weight near the reported ANC values and yield narrower posteriors. For $S_{E2}(300~\mathrm{keV})$, the analysis includes the interference of the radiative transition through the subthreshold resonance with the direct capture to the ground-state, which depends on the ground-state ANC $C_{0}$, giving broad posterior with $68\%$ credible interval spanning $[30.7,\,50.5]$~keV\,b. The Gaussian priors centered near anchor values. The resulting posteriors quantify both correlations and uncertainties: despite incorporating the published ANC constraints, the $68\%$ intervals remain broad, showing that present ANC determinations do not yet reduce the astrophysical uncertainty. Overall, the Bayesian framework provides statistically robust posteriors for $S_{E1}(300~\mathrm{keV})$ and $S_{E2}(300~\mathrm{keV})$, improving the reliability of extrapolations for stellar modeling and nucleosynthesis.

Intergalactic weak magnetic fields can have non-negligible effects on the electromagnetic cascades induced by blazar gamma-ray emission. Secondary electrons and positrons are produced by primary gamma rays of energies ~TeV and can be magnetically deflected out of the line of sight to the observer. However, these leptons can perturb the background intergalactic medium (IGM), resulting in the growth of plasma instabilities, which can also influence the electromagnetic cascade. The resulting gamma-ray spectrum, observable in the GeV-TeV energy range, can bear imprints of these two competing phenomena: deflection by the intergalactic magnetic field and plasma instability cooling. We present the results of numerical simulations that incorporate the combined impact of these two processes on the propagated gamma-ray spectrum of the blazar 1ES 0229+200.

Transmission spectroscopy is an effective technique for probing exoplanetary atmospheres. While most observations have relied on space facilities such as HST and JWST, ground-based high-resolution transmission spectroscopy (HRTS) has also provided valuable insights by resolving individual atomic features. In this work, we present an initial performance assessment and feasibility test of the Hanle Echelle Spectrograph (HESP) on the 2 m Himalayan Chandra Telescope (HCT) for HRTS. As a benchmark, we observed the hot Jupiter HD 209458b during a single transit at a resolution of R = 30,000. We developed a Python-based, semi-automated data reduction and analysis pipeline that includes corrections for telluric contamination and stellar radial velocity shifts. The final achieved signal-to-noise ratio and spectral stability allow us to probe for features at the 0.1% level. This work establishes a methodology and demonstrates the operational capability of the HESP-HCT for obtaining high-resolution transmission spectra.

One prominent feature of solar cycle is its irregular variation in its cycle strength, making it challenging to predict the amplitude of the next cycle. Studies show that fluctuations and nonlinearity in generating poloidal field throughout the decay and dispersal of tilted sunspots produce variation in the solar cycle. The flux, latitudinal position, and tilt angle of sunspots are the primary parameters that determine the polar field and, thus, the next solar cycle strength. By analysing the observed sunspots and polar field proxy, we show that the nonlinearity in the poloidal field generation becomes important for strong cycles. Except for strong cycles, we can reasonably predict the polar field at the end of the cycle (and thus the next cycle strength) using the total sunspot area alone. Combining the mean tilt angle and latitude positions with the sunspot area, we can predict the polar field of Cycles 15 -- 24 (or the amplitude of sunspot Cycles 16-25) with reasonable accuracy except for Cycle 23 for which the average tilt angle cannot predict the polar field. For Cycles 15--22, we show that the average tilt angle variation dominates over the latitude variation in determining the polar field of a cycle. In particular, the reduction of tilt in Cycle 19 was the primary cause of the following weak cycle (Cycle 20). Thus, we conclude that tilt quenching is essential in regulating the solar cycle strength in the solar dynamo.

The geometry of a star's Alfvén surface determines stellar angular momentum loss, separates a causally distinct 'corona' and stellar wind, and potentially affects exoplanetary habitability. The solar Alfvén surface is the only such structure that is directly measurable and since 2021, has been routinely measured in situ by NASA's Parker Solar Probe (Parker). We use these unique measurements in concert with Solar Orbiter and L1 in situ data spanning the first half of the Solar Cycle 25 in time and from 0.045 - 1 au in heliocentric distance to develop a radial scaling technique to estimate the morphology of the Alfvén surface from measurements of the solar wind speed and local Alfvén speed. We show that accounting for solar wind acceleration and mass flux is necessary to achieve reasonable agreement between the scaled location of the Alfvén surface and the locations of direct crossings measured by Parker. We produce continuous 2D equatorial cuts of the Alfvén surface over half a Solar Cycle (ascending phase and maximum). Parker's earliest crossings clipped outward extrusions, many of which are likely transient related, while more recently Parker has unambiguously sampled deep sub-Alfvénic flows. We analyze the average altitude, departure from spherical symmetry, and surface roughness, finding that all are positively correlated to solar activity. For the current modest Solar Cycle, the height varies up to 30\% which corresponds to a near-doubling in angular momentum loss per unit mass loss.

High-energy cosmic rays are observed indirectly by detecting the extensive air showers initiated in Earth's atmosphere. The interpretation of experimental data relies on accurate modeling of the air shower development. Simulations based on current hadronic interaction models show significant discrepancies with measurements of the muon content in air showers, commonly referred to as the Muon Puzzle, indicating severe shortcomings in the understanding of particle physics. A hybrid detector design with a surface array and deep underground detector, such as the IceCube Neutrino Observatory, allows simultaneous measurements of muons at two vastly different energies: at GeV energies and above a few 100GeV. We present phenomenological studies of low-energy and high-energy muons in simulated air showers, and discuss how hybrid measurements can provide constraints on multi-particle production in hadronic interaction models.

Bipolar Magnetic Regions (BMRs) that appear on the solar photosphere are surface manifestations of the solar internal magnetic field. With modern observations and continuous data streams, the study of BMRs has moved from manual sunspot catalogs to automated detection and tracking methods. In this work, we present an additional module to the existing BMR tracking algorithm, AutoTAB, that focuses on identifying emerging signatures of BMRs. Specifically, for regions newly detected on the solar disk, this module backtracks the BMRs to their point of emergence. From a total of about 12000 BMRs identified by AutoTAB, we successfully backtracked 3080 cases. Within this backtracked sample, we find two distinct populations. One group shows the expected behaviour of emerging regions, in which the magnetic flux increases significantly during the emerging phase. The other group consists of BMRs whose flux, however, does not exhibit substantial growth during their evolution. We classify these as non-emerging BMRs and examine their statistical properties separately. Our analysis shows that these non-emerging BMRs do not display any preferred tilt angle distribution nor show systematic latitudinal tilt dependence, in contrast to the trends typically associated with emerging BMRs. This indicates that including such regions in statistical studies of BMR properties can distort or mask the underlying physical characteristics. We therefore emphasise the importance of excluding the non-emerging population from the whole dataset when analysing the statistical behaviour of BMRs.

Many potential direct imaging candidates suffer from large orbital period uncertainties, leading to challenges in accurate predictions of future orbital positions and imprecise direct imaging measurements of planetary parameters. To improve the precision in orbital properties, precursor radial velocity (RV) follow-up observations for selected candidates are essential. This study examines the impact of three variables on the orbital period uncertainties of long-period giant planets: the number of future observations, the temporal gap between past and future data, and the temporal coverage of upcoming observations. Our simulations indicate that the orbital phases at which future RV observations are acquired play a significant role in reducing period uncertainties. Additionally, observing too frequently within a given time frame adds limited value to the program once a certain number of observations has been achieved. The temporal gap proves to be the most important factor when there is no strict end time to the observing campaign. However, if a strict end time is set, starting observations earlier yields improved reductions in orbital period uncertainty. These insights offer practical guidance for planning efficient RV follow-up campaigns to maximize the science yield of future space-based direct imaging missions.

Context. In recent years, changing-look blazars have put into question the traditional BL Lacs-flat spectrum radio quasars empirical classification of blazars based on the intensity of optical spectral lines, as they appear to transition between the two classes over time. Aims. We focus on the blazar 5BZQ J1243+4043, recently proposed as a promising candidate for the emission of high-energy neutrinos observed by the IceCube Neutrino Observatory and reported as a changing look in the literature. We study the spectral properties of this blazar, inferring its radiation field and accretion regime properties among different epochs. Methods. This study presents new optical spectroscopy observations of 5BZQ J1243+4043 taken with the Gran Telescopio Canarias. We use this new dataset and two optical spectra available from the literature to investigate the continuum and line emissions and pinpoint the physical properties of the source. Results. The newly collected data for 5BZQ J1243+4043 shows broad emission lines, consistent with the spectrum of the first epoch and the redshift $z = 1.5181\pm0.0002$ known from the literature. For the second epoch, the spectrum appears featureless, and we place limits on the emission lines and related physical properties. We observe spectral variability for both the continuum and line emissions among the three spectra. Despite this, the accretion properties of the blazar remain, overall, unvaried, indicating that the intrinsic physics remains the same across the three epochs. In the broader multi-messenger context, this suggests that, despite the changing look in the optical band, the candidate neutrino-emitter blazar 5BZQ J1243+4043 remains characterized by the presence of intense external radiation fields and radiatively efficient accretion, typical of high-excitation radio galaxies, that may foster neutrino production.

Between 40$\%$ and 80$\%$ of cataclysmic variables (CVs) are expected to have evolved past the period-minimum and contain a degenerate donor. However, observational surveys for CVs have only been able to detect a few of these highly evolved "period-bouncers", most likely due to the intrinsic faintness associated with their predicted low mass accretion rates. We have produced an initial selection of 137 high-likelihood period-bounce candidates from WD catalog based on our multiwavelength period-bouncer scorecard and selection cuts including X-ray data from the extended ROentgen Survey with an Imaging Telescope Array (eROSITA) on board the Spektrum-Roentgen-Gamma spacecraft (SRG). We have laid out three main requirements (classification as a CV, determination of an orbital period and detection of a very late-type donor) that should result in the confirmation of several of these candidates. Our path for confirming these candidates has already produced its first successful result with the confirmation of GALEX J125751.4-283015 as a new period-bouncer. Several other candidates have already fulfilled at least one of our three requirements making their future confirmation likely. Our search for period-bouncers using the X-ray eROSITA emission of objects in optical WD catalogs has led to the confirmation of six new period-bouncers identified from the Gaia DR3 WD catalog (five previously known CVs and one WD candidate), a 18$\%$ increase that brings the present population to 39 systems. Both the selection method for period-bounce candidates and the confirmation path that we outlined will aid in future searches for new period-bounce candidates, contributing to the goal of resolving the discrepancy between the predicted high number of period-bouncers and the low number of these systems successfully observed to date.

Ultra-short period (USP) exoplanets -- with $R_p \leq 2~$R$_{\oplus}$ and periods $\leq$1 day -- are expected to be stripped of volatile atmospheres by intense host star irradiation, which is corroborated by their nominal bulk densities and previous eclipse observations consistent with bare rock surfaces. However, a few USP planets appear anomalously under-dense relative to an Earth-like composition, suggesting an exotic interior structure (e.g., core-less) or a volatile-rich secondary atmosphere increasing their apparent radius. Here we present the first dayside emission spectrum of the low density (4.3$\pm$0.4 g~cm$^{-3}$) ultra-short period planet TOI-561 b, which orbits an iron-poor, alpha-rich, $\sim$10 Gyr old thick disk star. Our 3-5 $\mu$m JWST/NIRSpec observations demonstrate the dayside of TOI-561 b is inconsistent with a bare-rock surface at high statistical significance, suggesting instead a thick volatile envelope that is cooling the dayside to well below the $\sim$3000 K expected in the bare rock or thin atmosphere case. These results reject the popular hypothesis of complete atmospheric desiccation for highly irradiated exoplanets and support predictions that planetary-scale magma oceans can retain substantial reservoirs of volatiles, opening the geophysical study of ultra-hot super-Earths through the lens of their atmospheres.

This paper presents a low-noise amplifier (LNA) that was developed for a new radio telescope comprised of 512 parabolic dish antennas. The LNA closely interfaces to a custom-made antenna feed with an impedance co-designed to provide noise matching over a 5:1 bandwidth. Additionally, a method of broadband noise and power matching that allows the input impedance to be controlled independently from the optimum signal-source impedance to achieve minimum noise is also discussed. When measured in a 50-\Omega system, the LNA exhibits a return loss (RL) of > 8 dB between 0.32 to 1.5 GHz, S21 of 32 dB \pm 1.2 dB, IP1dB > -37 dBm, and IIP3 > -20 dBm. Noise parameter measurements show Tmin \approx 13 \pm 4K and noise temperatures T50{\Omega} \approx 18 \pm 6K between 0.5 to 1.4 GHz.

Using a two-fluid approach, we consider the properties of relativistically nonlinear (arbitrary $a_0$), circularly polarized electromagnetic waves propagating along magnetic field in electron-ion and pair plasmas. Dispersion relations depend on how wave intensity scales with frequency, $a_0 (\omega)$. For superluminal branches, the nonlinear effects reduce the cut-off frequency, while the general form of the dispersion relations $\omega(k)$ remains similar to the linear case. For subluminal waves, whistlers and Alfven, a new effect appears: dispersion curves effectively terminate at finite $\omega^\ast - k^\ast$ due to current starvation. Qualitatively, subluminal modes with fluctuating electric field larger than the guide field, $E_w (\omega) \geq B_0$, cannot propagate.

In this contribution, we have investigated the energy spectra of the elemental mass groups of cosmic rays for the Light (H+He), medium (C+O) and heavy (Ne-Fe) components using the High Altitude Water Cherenkov Gamma-Ray observatory (HAWC). The study was carried out in the energy interval from $10$ TeV to $1$ PeV using almost $5$ years of data on hadronic air showers. The energy spectra were unfolded using the bidimensional distribution of the lateral shower age versus the reconstructed primary energy. We have employed the QGSJET-II-04 high-energy hadronic interaction model for the current analysis. The results show the presence of fine structure in the spectra of the light, medium and heavy mass groups of cosmic rays.

In the last two decades, different advances with extensive air shower (EAS) experiments have allowed to unveil several details about the composition and energy spectrum of galactic cosmic rays from some TeV up to several hundreds of PeV, which have led to improve our understanding of the physics of cosmic rays. EAS measurements above the knee, for instance, have helped to understand some aspects about the acceleration and propagation mechanisms of the PeV component of cosmic rays and have shown possible hints about the transition from the galactic to the extragalactic regime. Meanwhile, EAS data in the TeV energy range have revealed unexpected features in the all-particle and elemental spectra, which may indicate the presence of previously unknown cosmic-ray phenomena. In this contribution, I will present a brief account on these EAS results, with particular emphasis on the recent measurements of the all-particle energy spectrum and the elemental composition of cosmic rays from 10 TeV up to 1 EeV. In addition, I will compare the latest results of EAS experiments and direct detectors at energies just below the knee, where there exists an overlap between both detection techniques.

Atmospheric dispersion introduces wavelength-dependent effects that significantly impact ground-based observations, particularly in slit- and fibre-fed spectroscopic studies. These effects reduce the signal entering the spectrograph and introduce systematic errors in radial velocity measurements. To address this challenge, atmospheric dispersion correctors are utilised. However, many existing designs of these correctors, which are based on theoretical models, often lack practical validation and consistency. The forthcoming National Large Optical Telescope (NLOT) will be installed at Hanle, a site known for its favourable astronomical sky conditions. Thus, the design of an effective dispersion corrector for the instruments on the NLOT, specifically one that compensates for the measured dispersion, is crucial. For the first time, we have directly measured atmospheric dispersion at the Hanle site using the Himalayan Faint Object Spectrograph mounted on the Himalayan Chandra Telescope. In this study, we present our methodology, the dispersion measurements obtained within the 400 to 700 nm wavelength range, and a comparison with modelled dispersion values.

The interstellar medium (ISM) exhibits complex, multi-scale structures that are challenging to study due to their projection into two-dimensional (2D) column density maps. We present the Volume Density Mapper, a novel algorithm based on constrained diffusion to reconstruct three-dimensional (3D) density distributions of molecular clouds from 2D observations. This method decomposes the column density into multi-scale components, reconstructing a 3D density field that preserves key physical properties such as mean density, maximum density, and standard deviation along the line of sight. Validated against numerical simulations (FLASH and ENZO), the algorithm achieves high accuracy, with mean density estimates within 0.1 dex and dispersions of 0.2 to 0.3 dex across varied cloud structures. The reconstructed 3D density fields enable the derivation of critical parameters, including volume density, cloud thickness, and density probability distribution functions, offering insights into star formation and ISM evolution. The versatility of the method is demonstrated by applying diverse systems from galaxies (NGC 628) to protostellar disks. The code is available at this https URL.

(Abridged) The present-day spatial and kinematic distribution of stars in the Milky Way provides key constraints on its internal dynamics and evolutionary history. We select stars that are more metal-rich than the interstellar medium (ISM) at their guiding radius (the so-called Local Metal-Rich stars, LMR) and investigate their chemo-kinematics. Until recently, existing catalogues did not contain such targets in large quantities, but one can now select many millions of them by using Gaia photometric metallicities. Once selected, we investigate their kinematics and age distributions across the disc, and compare them to the stellar populations having the metallicity of the ISM. Compared to locally born stars with [M/H]=[M/H]_ISM, we find that LMR stars, at a given location, are always older (mean age up to 2 Gyr older) and with velocity dispersions similar or slightly higher. Furthermore, at a given [M/H], LMR stars are older at larger galactocentric radiii, reflecting the fact that they need time to migrate. Finally, whereas we do not find any correlation between the location of the spiral arms and the spatial density of LMR stars, we find that the mean stellar eccentricity and mean ages show smaller values where the spiral arms are. Our results confirm a well established theoretical result that has not yet been formally confirmed via observations on large datasets without modelling: churning is not significantly heating the Galactic disc. Furthermore, the age distribution of these stars rule-out any significant contribution from Galactic fountains as their origin, and confirm the effect of the spiral arms on them.

A considerable proportion of young stars belong to multiple star systems. Constraining the planet formation processes in multiple stellar systems is then key to understand the global exoplanet population. This study focuses on investigating the dust reservoir within the triple system V892 Tau. Our objective is to establish constraints on the properties and characteristics of the dust present in the system's circumbinary ring. Based on archival ALMA and VLA data from 0.9 mm to 9.8 mm, we present a multi-wavelength analysis of the ring of V892 Tau. We first studied the spatial variation of the spectral index, before employing 3D full radiative transfer calculations to constrain the ring's geometry and the radial dependence of the dust grain properties. Spectral indices are consistent with non-dust emission in the vicinity of the central binary, and with dust emission in the ring likely remaining optically thick up to 3.0 mm. Our radiative transfer analysis supports these interpretations, yielding a model that reproduces the observed intensities within the 1-sigma uncertainties across all wavelengths. The resulting dust surface density and temperature profiles both decrease with increasing radius, and are in agreement with values reported in the literature. Maximum grain sizes are constrained to 0.2 cm, with a size distribution power-law index -3.5. These results imply that the dust grain fragmentation velocity does not exceed 8 m/s. Whilst our results suggest dust trapping at the cavity edge, they also suggest that tidal perturbations triggered by the central binary limit grain growth within the ring. This highlights the need to further constrain planet formation efficiency in multiple stellar systems, a goal that may be advanced by applying the methodology of this work to a wider sample of systems.

Black hole population studies are currently performed either using astrophysically motivated models (informed but rigid in their functional forms) or via non-parametric methods (flexible but not directly interpretable). In this paper, we present a statistical framework to complement the predictive power of astrophysically motivated models with the flexibility of non-parametric methods. Our method makes use of the Dirichlet distribution to robustly infer the relative weights of different models as well as of the Gibbs sampling approach to efficiently explore the parameter space. After having validated our approach using simulated data, we apply this method to the BBH mergers observed during the first three Observing Runs of the LIGO-Virgo-KAGRA collaboration using both phenomenological and astrophysical models as parametric models, finding results in agreement with the currently available literature.

The $\Lambda$ cold dark matter ($\Lambda$CDM) cosmological model provides a good description of a wide range of astrophysical and cosmological observations. However, severe challenges to the phenomenological $\Lambda$CDM model have emerged recently, including the Hubble constant tension and the significant deviation from the $\Lambda$CDM model reported by the Dark Energy Spectroscopic Instrument (DESI) collaboration. Despite many explanations for the two challenges have been proposed, the origins of them are still intriguing mysteries. Here, we investigate the DESI Baryon Acoustic Oscillations (BAOs) measurements to interpret the Hubble constant tension. Employing a non-parametric method, we find that the dark energy equation of state $w(z)$ evolves with redshift from DESI BAO data and type Ia supernovae. From the Friedmann equations, the Hubble constant ($H_0$) is derived from $w(z)$ model-independently. We find that the values of $H_0$ show a descending trend as a function of redshift, and can effectively resolve the Hubble constant tension. Our study finds that the two unexpected challenges to the $\Lambda$CDM model can be understood in one physical framework, e.g., dynamical dark energy.

Gamma-Ray Bursts (GRBs) afterglows are rapidly decaying signals that pose significant detection challenges, requiring improved methods to track their temporal evolution. In this study, we systematically compare various techniques for detecting GRB-like transient emissions at very high energies (VHE, >100 GeV). Our analysis includes time-dependent extension of the standard method (i.e., Li & Ma 1983) and other previously developed methods in the literature, alongside a novel likelihood-based approach, which directly fits spectral and temporal decay features to IACT data. Through dedicated observation simulations, we evaluate the performance of these methods for the Large-Sized Telescope prototype (LST-1) of the Cherenkov Telescope Array Observatory (CTAO). We characterised the enhanced sensitivity found in some of these methods compared to the standard significance estimation. For GRBs simulated with very fast afterglow decay, an improvement of more than a factor of two is seen in detections for some of the methods presented here, compared to the standard Li&Ma approach.

Both the Galactic center and LRDs host million-solar-mass black holes within dense, cold reservoirs of molecular gas, and are electromagnetically tranquil. These conditions enable complex molecular chemistry and may serve as natural laboratories for prebiotic genetic evolution by allowing the synthesis of organic molecules essential for life.

Analysis of radio emission from tidal disruption events allows for detailed constraints on the properties of ejected outflows and the host environment surrounding the black hole. However, the late-time radio behaviour of tidal disruption events is not well-studied due to a lack of observations. In this work we present long-term radio monitoring observations of the tidal disruption event AT2019azh spanning 1167-2159 days post disruption. We fit a physically motivated synchrotron model to the radio spectra at each epoch, and model the decay of the light curve under the assumption that the outflow transitions into the non-relativistic Sedov-Taylor regime at late times. Through this modelling we obtain strong constraints on the density profile of the circumnuclear medium, finding an unusually flat density profile proportional to $r^{0.24^{+0.11}_{-0.15}}$. Overall we find that unlike some tidal disruption events, AT2019azh does not show late time re-brightening up to 6 years post-disruption. The Sedov-Taylor light curve decay model provides a good fit to the data, motivating the assumption that the outflow was produced by a single ejection of material close to the time of stellar disruption. From forward modelling the evolution of the radio light curve decay we predict that the radio afterglow from AT2019azh should be detectable for decades at its current rate of evolution.

Kaniadakis Holographic Dark Energy is a one-parameter extension of the standard HDE framework, in which the horizon entropy is reformulated using Kaniadakis entropy. At the cosmological level, it has been shown to give rise to modified Friedmann equations, leading to a richer phenomenology compared to $\Lambda$CDM. In this work we test the Kanadiakis holography model against multiple late-time observational probes, including Type Ia supernovae from PantheonPlus and Union3, Cosmic Chronometer measurements of the Hubble parameter and Baryon Acoustic Oscillation from the Dark Energy Spectroscopic Instrument Data Release 2 (DESI DR2). Using a Bayesian inference approach with MCMC methods, we constrain the cosmological parameters of the model and evaluate its performance against $\Lambda$CDM through the Akaike Information Criterion. We find that Kaniadakis holography can provide a better fit for some data combinations, although $\Lambda$CDM remains slightly statistically favored overall. These results highlight Kaniadakis holography as a competitive alternative to the standard cosmological model, offering valuable insights into the role of generalized entropy in dark energy dynamics.

It is well-known that star-forming galaxies (SFGs) exhibit a tight correlation between their radio and infrared emissions, commonly referred to as the infrared-radio correlation (IRRC). Recent empirical studies have reported a dependence of the IRRC on the galaxy stellar mass, in which more massive galaxies tend to show lower infrared-to-radio ratios (qIR) with respect to less massive galaxies. One possible, yet unexplored, explanation is a residual contamination of the radio emission from active galactic nuclei (AGN), not captured through "radio-excess" diagnostics. To investigate this hypothesis, we aim to statistically quantify the contribution of AGN emission to the radio luminosities of SFGs located within the scatter of the IRRC. Our VLBA program "AGN-sCAN" has targeted 500 galaxies that follow the qIR distribution of the IRRC, i.e., with no prior evidence for radio-excess AGN emission based on low-resolution (~ arcsec) VLA radio imaging. Our VLBA 1.4 GHz observations reach a 5-sigma sensitivity limit of 25 microJy/beam, corresponding to a radio brightness temperature of Tb ~ 10^5 K. This classification serves as a robust AGN diagnostic, regardless of the host galaxy's star formation rate. We detect four VLBA sources in the deepest regions, which are also the faintest VLBI-detected AGN in SFGs to date. The effective AGN detection rate is 9%, when considering a control sample matched in mass and sensitivity, which is in good agreement with the extrapolation of previous radio AGN number counts. Despite the non-negligible AGN flux contamination (~ 30%) in our individual VLBA detections, we find that the peak of the qIR distribution is completely unaffected by this correction. We conclude that residual AGN contamination from non-radio-excess AGN is unlikely to be the primary driver of the M* - dependent IRRC.

The halo model, combined with halo occupation distribution (HOD) prescriptions, is widely used to interpret cosmic infrared background (CIB) anisotropies and connect star-forming galaxies to large-scale structure. Recent implementations adopt more physical parameterizations, but it remains unclear whether these models reliably recover astrophysical quantities. We test whether current CIB halo models can constrain the star formation efficiency, $\eta(M_h,z)$, and the halo mass where it peaks, $M_{\rm max}$, when fitted to mock data. We examine whether discrepancies arise from emission assumptions (the HOD ingredients) or from more fundamental components, such as bias and matter clustering. Using the M21 CIB HOD model within the halo framework, we fit mock CIB power spectra and star formation rate density (SFRD) data from the SIDES-Uchuu simulation, then repeat the analysis with a simplified simulation (SSU) matched to the HOD assumptions. Comparing best-fit parameters to known inputs, we find that although the M21 model fits the mock data well, it fails to recover intrinsic parameters, especially $M_{\rm max}$, even when applied to data generated with consistent assumptions. Emission-related quantities (SFRD, emissivity) agree within 5%, but the two-halo term shows a redshift- and scale-dependent offset exceeding 20%, likely due to the linear treatment of halo bias and matter clustering. Scatter in the SFR-halo mass relation and spectral energy distributions significantly impacts shot noise ($\sim 50\%$) but only modestly ($<10\%$) the clustered signal. We conclude that robust recovery of physical parameters from CIB clustering requires improved cosmological ingredients in halo models, including scale-dependent halo bias and nonlinear matter power spectra, alongside refined emission modeling.

We present a multiphase, resolved study of the galactic wind extending from the nearby starburst galaxy NGC 4666. For this we use VLT/MUSE observations from the GECKOS program and HI data from the WALLABY survey. We identify both ionised and HI gas in a biconical structure extending to at least $z\sim$8 kpc from the galaxy disk, with increasing velocity offsets above the midplane in both phases, consistent with a multiphase wind. The measured electron density, using [SII], differs significantly from standard expectations of galactic winds. We find electron density declines from the galaxy centre to $\sim2$ kpc, then rises again, remaining high ($\sim100-300$ cm$^{-3}$) out to $\sim$5 kpc. We find that HI dominates the mass loading. The total HI mass outflow rate (above $z~>2$ kpc) is between $5-13~M_{\odot}~\rm yr^{-1}$, accounting for uncertainties from disk-blurring and group interactions. The total ionised mass outflow rate (traced by H$\alpha$) is between $0.5~M_{\odot}~\rm yr^{-1}$ and $5~M_{\odot}~\rm yr^{-1}$, depending on $n_e(z)$ assumptions. From ALMA/ACA observations, we place an upper-limit on CO flux in the outflow which correlates to $\lesssim2.9~M_{\odot}~\rm yr^{-1}$. We also show that the entire outflow is not limited to the bicone, but a secondary starburst at the edge generates a more widespread outflow, which should be included in simulations. The cool gas in NGC 4666 wind has insufficient velocity to escape the halo of a galaxy of its mass, especially because most of the mass is present in the slower atomic phase. This strong biconical wind contributes to gas cycling around the galaxy.

Ultra-high-energy (UHE) neutrinos are unique cosmic messengers that can traverse cosmological distances unattenuated, offering direct insight into the most energetic processes in the universe. Radio detection promises significant advantages for detecting highly inclined air showers induced by UHE neutrinos, including a larger exposure range compared to particle detectors, which is due to minimal atmospheric attenuation of radio signals combined with good reconstruction precision. Furthermore, this technique improves the air shower longitudinal reconstruction, which can be used to identify neutrinos with their first interaction far below the top of the atmosphere. In this work, we present a method for identifying UHE neutrinos using radio antennas deployed in ground-based observatories. We introduce a reconstruction algorithm based on the radio emission maximum ($X^{\text{radio}}_{\text{max}}$) and demonstrate its power in distinguishing deeply developing neutrino-induced showers from background cosmic rays. Using the Pierre Auger Observatory as a case study, we use the simulations of $\nu_e$-CC-induced air showers and evaluate the trigger efficiency, reconstruction performance, and resulting effective area. Our results show that radio detection significantly enhances the sensitivity to very inclined showers above 1~EeV, complementing traditional surface detectors. This technique is highly scalable and applicable to future radio observatories such as GRAND. The proposed reconstruction and identification strategy provides a pathway toward achieving the sensitivity needed to detect UHE neutrinos.

Current cosmological data seem to show that dark energy is evolving in time and that it possibly crossed the phantom divide in the past. So far the only theories that lead to such a behavior involve a non-trivial coupling between dark energy, in the form of a scalar field, and the gravitational or matter sector. We show that there is another possibility involving both a non-trivial kinetic sector in a cubic Galileon theory and a scalar field potential that breaks the Galileon shift symmetry, which can lead to a similar phenomenology on large scales. We perform a full Bayesian analysis using the latest cosmological data, including DESI DR2 BAO measurements, type Ia SNe measurements from DESY5, Union3, and Pantheon+, and CMB data from Planck and ACT. We find that it is statistically strongly favored over a Universe dominated by a cosmological constant (with a Bayes factor of $\log B\simeq 6.5$). Yet, as with other non-minimally coupled theories, it has severe ancillary gravitational effects. These can be mitigated to some extent, but as with other viable theories, the penalty is ever more elaborate scalar field models of dark energy.

Hawking's groundbreaking prediction that black holes emit thermal radiation and ultimately evaporate remains unverified due to the extreme faintness of this radiation for stellar-mass or larger black holes. In this study, we explore a novel observational strategy to search for Hawking radiation from asteroid-mass black hole morsels -- hypothetical small black holes that may form and be ejected during catastrophic events such as binary black hole mergers. These black hole morsels are expected to emit gamma rays in the GeV-TeV range on observable timescales. We analyze data from the Fermi Large Area Telescope coinciding with the well-localized binary black hole merger GW170814, searching for delayed gamma-ray signatures associated with morsel evaporation. While we find no evidence for such emission, we place exclusion limits on morsel masses, ruling out the 4 x 10^8 kg scenario at the 95 percent confidence level for a total emitted mass of one solar mass. We also outline future directions, including the incorporation of late-time evaporation spikes, systematic application across the growing gravitational wave catalog, and the enhanced discovery potential of next-generation facilities such as the Cherenkov Telescope Array Observatory.

In this paper, we develop a Neural Likelihood Estimator and apply it to analyse real gravitational-wave (GW) data for the first time. We assess the usability of neural likelihood for GW parameter estimation and report the parameter space where neural likelihood performs as a robust estimator to output posterior probability distributions using modest computational resources. In addition, we demonstrate that the trained Neural likelihood can also be used in further analysis, enabling us to obtain the evidence corresponding to a hypothesis, making our method a complete tool for parameter estimation. Particularly, our method requires around 100 times fewer likelihood evaluations than standard Bayesian algorithms to infer properties of a GW signal from a binary black hole system as observed by current generation ground-based detectors. The fairly simple neural network architecture chosen makes for cheap training, which allows our method to be used on-the-fly without the need for special hardware and ensures our method is flexible to use any waveform model, noise model, or prior. We show results from simulations as well as results from GW150914 as proof of the effectiveness of our algorithm.

Silicon photomultipliers (SiPMs) are increasingly favored for detecting near-UV, visible, and infrared light in space due to their high sensitivity to single photons and compact design. While SiPMs offer several advantages over traditional photomultiplier tubes, their susceptibility to radiation and noise remains an issue. Our study intended to determine the optimal SiPM design for the Terzina Cherenkov satellite in sun-synchronous low Earth orbit (LEO) at an altitude of 550 km. To this end, we characterised several NUV-HD-MT SiPM variants, developed by Fondazione Bruno Kessler, and studied their responses to irradiation by exposing them to a 50 MeV proton beam and to electrons from the $\beta$-emitting source strontium-90. Experimental results were cross-validated with SPENVIS and Geant4 simulations. Based on our findings, we also propose an annealing strategy to mitigate radiation damage and ensure reliable performance in space-based applications.

Asteroid families are typically identified using hierarchical clustering methods (HCM) in the proper element phase space. However, these methods struggle with overlapping families, interlopers, and the detection of older structures. Spectroscopic data can help overcome these limitations. The Gaia Data Release 3 (DR3) contains reflectance spectra at visible wavelengths for 60,518 asteroids over the range between 374-1034 nm, representing a large sample that is well suited to studies of asteroid families. Using Gaia spectroscopic data, we investigate a region in the central Main Belt centered around 2.72 AU, known for its connection to L- type asteroids. Conflicting family memberships reported by different HCM implementations underscore the need for an independent dynamical analysis of this region. We determine family memberships by applying a color taxonomy derived from Gaia data and by assessing the spectral similarity between candidate members and the template spectrum of each family. We identify an L- type asteroid family in the central Main Belt, with (460) Scania as its largest member. Analysis of the family's V-shape indicates that it is relatively old, with an estimated age of approximately 1 Gyr, which likely explains its non detection by the HCM. The family's existence is supported by statistical validation, and its distribution in proper element space is well reproduced by numerical simulations. Independent evidence from taxonomy, polarimetry, and spin-axis obliquities consistently supports the existence of this L- type family. This work highlights the value of combining dynamical and physical data to characterize asteroid families and raises questions about the origin of L- type families, potentially linked to primordial objects retaining early protoplanetary disk properties. Further spectroscopic data are needed to clarify these families.

We present RAVEN, a newly developed vetting and validation pipeline for TESS exoplanet candidates. The pipeline employs a Bayesian framework to derive the posterior probability of a candidate being a planet against a set of False Positive (FP) scenarios, through the use of a Gradient Boosted Decision Tree and a Gaussian Process classifier, trained on comprehensive synthetic training sets of simulated planets and 8 astrophysical FP scenarios injected into TESS lightcurves. These training sets allow large scale candidate vetting and performance verification against individual FP scenarios. A Non-Simulated FP training set consisting of real TESS candidates caused primarily by stellar variability and systematic noise is also included. The machine learning derived probabilities are combined with scenario specific prior probabilities, including the candidates' positional probabilities, to compute the final posterior probabilities. Candidates with a planetary posterior probability greater than 99% against each FP scenario and whose implied planetary radius is less than 8$R_{\oplus}$ are considered to be statistically validated by the pipeline. In this first version, the pipeline has been developed for candidates with a lightcurve released from the TESS Science Processing Operations Centre, an orbital period between 0.5 and 16 days and a transit depth greater than 300ppm. The pipeline obtained area-under-curve (AUC) scores > 97% on all FP scenarios and > 99% on all but one. Testing on an independent external sample of 1361 pre-classified TOIs, the pipeline achieved an overall accuracy of 91%, demonstrating its effectiveness for automated ranking of TESS candidates. For a probability threshold of 0.9 the pipeline reached a precision of 97% with a recall score of 66% on these TOIs. The RAVEN pipeline is publicly released as a cloud-hosted app, making it easily accessible to the community.

The PRobe far-Infrared Mission for Astrophysics (PRIMA) is a cryogenically-cooled, far-infrared (far-IR) observatory expected to begin serving the astronomical community by early 2030. The mission features two advanced instruments: PRIMAger and FIRESS. PRIMAger will operate across the mid- to far-IR spectrum, covering wavelengths from approximately 25 to 260 $\mu$m. It will offer hyperspectral imaging in medium resolution bands (R $\sim$ 8, using a linear variable filter) from 25 to 80 $\mu$m, and broad band (R $\sim$ 4) photometric and polarimetric imaging in four bands spanning 80 to 260 $\mu$m. The capabilities of PRIMAger will enable a broad range of unique scientific programs, accessible through General Observer (GO) projects. In this paper, we present and define a PRIMAger survey over 25\% of the sky, called $\pi$-IR survey. This survey would exploit PRIMAger's hyperspectral and polarimetric modes to collect data on about 8 $\times$ 10$^{6}$ galaxies to z $\sim$ 4. The R=8 spectral resolution of the PRIMAger Hyperspectral Imaging (PHI) filters will enable users to study the emission of polycyclic aromatic hydrocarbon (PAH). A large sample of galaxies will be observed with the polarimetric bands of PRIMAger, allowing unique statistical information for galaxies to be harvested for the first time.

The seasonal variation of single muons is a well-understood phenomenon, mainly driven by a positive correlation with temperature fluctuations in the atmospheric profiles. However, the rate of multi-muon events recorded by various experiments has shown an intriguing opposite seasonal modulation that remains unexplained by previous research. For the first time, we quantitatively describe the phase and amplitudes of the seasonal variation for cosmic multi-muon events detected by the NO$\nu$A Near Detector. We can further explain the amplitude dependence for multi-muon events across various multiplicities. For our analysis, we use the general-purpose Monte Carlo code FLUKA-CERN 4.4.1, which provides a more realistic description of the detector, atmospheric profiles, and muon propagation underground. Finally, we compare our results with those obtained from the latest CORSIKA version 7.8010, utilizing the most up-to-date high-energy hadronic interaction models EPOS LHC-R and QGSJETIII-01. Our findings provide a fresh perspective on seasonal muon flux modulation and offer key constraints for cosmic-ray interaction models and underground detector studies.

The ongoing exponential growth of computational power, and the growth of the commercial High Performance Computing (HPC) industry, has led to a point where ten commercial systems currently exceed the performance of the highest-used HPC system in radio astronomy in Australia, and one of these exceeds the expected requirements of the Square Kilometre Array (SKA) Science Data Processors. In order to explore implications of this emerging change in the HPC landscape for radio astronomy, we report results from a survey conducted via semi-structured interviews with 14 Australian scientists and providers with experience of commercial HPC in astronomy and similar data intensive fields. We supplement these data with learnings from two earlier studies in which we investigated the application of commercial HPC to radio astronomy data processing, using cases with very different data and processing considerations. We use the established qualitative research approach of thematic analysis to extract key messages from our interviews. We find that commercial HPC can provide major advantages in accessibility and availability, and may contribute to increasing researchers' career productivity. Significant barriers exist, however, including the need for access to increased expertise in systems programming and parallelisation, and a need for recognition in research funding. We comment on potential solutions to these issues.

Despite decades of direct and indirect searches within the Weakly Interacting Massive Particle (WIMP) framework, no conclusive results have been found in the GeV--TeV range. This has motivated exploring alternatives, including new particles and macroscopic objects. Two well-motivated scenarios are sub-GeV DM and Primordial Black Holes (PBHs). Molecular clouds (MCs), typically studied as star-forming sites, can serve as astrophysical laboratories to probe these candidates via their ionization rates. Observations show ionization levels exceeding expectations from known CR fluxes, pointing to an additional ionizing component. Here, we consider electrons and positrons from annihilating and decaying MeV DM particles, as well as Hawking radiation from evaporating PBHs, as possible contributors. We model transport driven by energy losses within the clouds. By comparing predicted ionization rates with observations, conservative constraints are set on the thermally averaged cross section $\langle\sigma v\rangle$, decay lifetime $\tau$ and PBH abundances $f_{PBH}$. The analysis assumes all the observed ionization comes from DM and adopts a 95% confidence level. Results show that, even in the most conservative case of local MCs such as L1551, these constraints are very close to the most competitive bounds from X-ray observations, while inner-Galaxy clouds like DRAGON or G1.4--1.8+87 provide stronger limits, sometimes improving X-ray and cosmological constraints. For sub-GeV DM, MCs exclude parameter space competitive with the one tested by NuSTAR, INTEGRAL, or Voyager, especially below $\sim$30 MeV. In the PBH case, asteroid-mass black holes are restricted to a low fraction of DM, with optimistic scenarios getting close to the strongest limits. This demonstrates the potential of MCs as a novel probe in indirect DM searches.

Understanding the formation and evolution of the cosmic web of galaxies is a fundamental goal of cosmology, using various tracers of the cosmic large-scale structure at an ever wider range of redshifts. Our principal aim is to advance the mapping of the cosmic web at high redshifts using observational and synthetic catalogues of quasars (QSOs), which offer a powerful probe of structure formation and the validity of the concordance cosmological model. In this analysis, we selected 708,483 QSOs at $0.8<z<2.2$ from the Quaia data set, allowing a reconstruction of the matter density field using 24,372 deg$^2$ sky area with a well-understood selection function, and thus going beyond previous studies. Using the REVOLVER method, we created catalogues of voids and clusters based on the estimation of the local density at QSO positions with Voronoi tessellation. We tested the consistency of Quaia data and 50 mock catalogues, including various parameters of the voids and clusters in data subsets, and also measurements of the density profiles of these cosmic super-structures at $100 h^{-1}$Mpc scales. We identified 12,842 voids and 41,111 clusters in the distribution of Quaia QSOs. The agreement between data and mocks is at a level of 5-10%, considering void and cluster radii, average inner density, and density profiles. In particular, we tested the role of survey mask proximity effects in the void and cluster detection, which albeit present, are consistent in simulations and observations. The largest voids and clusters reach $R_{eff} \approx 250 h^{-1}$Mpc and $150 h^{-1}$Mpc, respectively, but without evidence for ultra-large cosmic structures exceeding the dimensions of the largest structures in the mocks. As an important deliverable, we share our density field estimation, void catalogues, and cluster catalogues with the public, allowing various additional cross-correlation probes at high-z.

Galaxy properties correlate with their position within the cosmic web. While galaxies are observed in an environment today, they may have experienced different environments in the past. The environmental history, linked to pre-processing, leaves an imprint on the properties of galaxies. We use the GAEA semi-analytic model and IllustrisTNG to reconstruct the environmental histories of galaxies between $z=0$ and $z=4$ that today reside in filaments. Our goal is to understand how galaxy properties are related to their past environments, and the role of the cosmic web in shaping their properties. We find that filament galaxies at $z=0$ are a heterogeneous mix of populations with distinct environmental histories. The vast majority of them have experienced group processing, with only $\sim$20\% remaining centrals throughout their life. For $\rm 9 < \log_{10}(M_{star}/M_{sun}) < 10$ galaxies, models confirm that the environmental effects are primarily driven by group processing: satellites stop growing stellar mass and exhibit elevated quenched fractions, whereas filament galaxies remain centrals have properties that are similar to field galaxies. Massive galaxies ($\rm \log_{10}(M_{star}/M_{sun}) > 10$) that have never been satellites and entered filaments more than 9 Gyr ago show accelerated stellar mass assembly and higher quenched fractions relative to the field, due to a higher frequency of merger events inside filaments, even at fixed mass. The most massive $\rm \log ((M_{star} / M_{sun}) > 11$) galaxies accreted onto filaments over 9 Gyr ago, highlighting the role of filaments in building up the high-mass end of the galaxy population. Filaments regulate galaxy evolution in a mass-dependent way: group environments regulate low-mass galaxies, while filaments favour the growth of massive galaxies.

Galaxy mergers are believed to play an important role in triggering rapid supermassive black hole (SMBH) growth. As merging nuclei approach each other, the physical properties of the participating galaxies and the associated SMBH growth are expected to evolve significantly. This study measures and characterizes these physical properties throughout the merger sequence. We constructed multiwavelength Spectral Energy Distributions (SEDs) from hard X-rays to the far-infrared (FIR) for a sample of 72 nearby Active Galactic Nuclei (AGN) host galaxies. The sample comprises 64 interacting systems, including single AGNs in mergers and dual AGNs, with nuclear separations $\leq$30 kpc, as well as eight isolated active galaxies with merging features. We carefully adapted available photometric measurements at each wavelength to account for their complex morphologies and varying spatial resolutions, to perform SED fitting using CIGALE, aimed to derive critical physical properties. Our results reveal that merging galaxies hosting AGN(s) show deviations from the star-forming main sequence, and a wide range of star formation rates (SFRs). Both AGN activity and star formation are significantly influenced by the merger process, but these effects are more prominent in major, mass ratios $<$4:1, interactions. We find that the projected nuclear separation is not a good tracer of the merger stage. Instead, morphological classification accurately assesses the merger progression. Based on this morphological analysis, late-stage mergers exhibit elevated SFRs (5.1$\times$), AGN luminosities (2.4$\times$), and nuclear obscuration (2.8$\times$) compared to earlier stages, supporting previous findings and reinforcing the link between merger-driven galaxy evolution and SMBH growth.

Seyfert-starburst composite galaxies host two promising phenomena of non-thermal high-energy radiation. In this regard the IceCube observation of high-energy neutrinos from the direction of the Seyfert-starburst composite galaxy NGC 1068 is not surprising. More recently, another Seyfert-starburst composite galaxy, NGC 7469, has shown hints for neutrino emission at even higher energies. Theoretical investigations could clarify that their so-called AGN corona is the most-likely origin of these neutrinos due to the need of being partially $\gamma$-ray opaque. In this work, we present an updated version of our Seyfert-starburst composite model from 2022, that accounts for a proper treatment of the stochastic acceleration processes in the AGN corona and the secondary electrons and positrons from leptonic radiation processes. Moreover, we use a Markov Chain Monte Carlo (MCMC) approach to study the parameter space of these two potential high-energy neutrino sources under consideration of the given prior knowledge. In the case of NGC 1068, we can successfully explain its non-thermal observational features, where both its AGN corona and starburst ring are needed to account for the observations at high- energies. In the case of NGC 7469, the high-energy signatures can only be explained assuming a small coronal radius and the including external $\gamma\gamma$-pair attenuation. In general, both sources exhibit a strong influence of the $\gamma$-ray opaqueness on the results, highlighting the need for an accurate treatment of the intrinsic coronal X-ray field and the spatial extent of the $\gamma$-ray production site.

We investigate the origin and formation mechanisms of the intra-cluster light (ICL) in The Three Hundred simulations, a set of 324 hydrodynamically resimulated massive galaxy clusters. The ICL, a diffuse component of stars not bound to individual galaxies, serves as a key tracer of cluster formation and evolution. Using two hydrodynamics implementations, Gadget-X and Gizmo-Simba, we identify the stellar particles comprising the ICL at z=0 and trace them back in time to the moments when they were formed and accreted into the ICL. Across our 324 clusters, half of the present-day ICL mass is typically in place between $z \sim $ 0.2 and 0.5. The main ICL formation channel is the stripping of stars from subhalos after their infall into the host cluster. Within this channel, 65-80 per cent of the ICL comes from objects with stellar (infall) masses above $10^{11}$ M$_\odot$, i.e., massive galaxies, groups and clusters. Considering the ratio of the infalling halo to the total cluster mass, a median of 35 per cent of the mass is brought in major merger events, though this percentage varies significantly across clusters (15-55 per cent). Additional contributions come from minor mergers (25-35 per cent) and smooth accretion (20-50 per cent). The primary contributors typically infall at $z \leq 1$, with smaller fractions arriving at redshifts between 1 and 2. Regarding other formation channels, we find minor contributions from stars formed in subhalos after their infall and stars stripped while their contributing halo remains outside the host cluster (and can eventually fall inside or stay outside). Finally, for our two sets of simulations, we find medians of 12 (Gadget-X) and 2 (Gizmo-Simba) per cent of the ICL mass formed in-situ, that is, directly as part of the diffuse component. However, this component can be attributed to stripping of gas in high-velocity infalling satellite galaxies.

We investigate the young stellar cluster population of M51 and how it is affected by encounters with giant molecular clouds (GMCs). We combine a galactic model with $N$-body simulations of 5000 unique clusters in the mass range [600 - 24000] $M_{\odot}$. We simulate each cluster twice: with ($C_R$) and without ($C_N$) tidal perturbations from the GMCs. We are able to reproduce the majority of the observed mass- and age functions. However, for the age function we see a large discrepancy for clusters with masses $\sim$ 5000 $M_{\odot}$, which is likely related to incompleteness in the observations. We find that old low-mass clusters, located close to the galactic centre, are most likely to be disrupted. The effect of GMC encounters causes a decrease in survivability by 8 per cent points for the oldest clusters with initial masses below 6000 $M_{\odot}$. For 15 clusters we find that the presence of GMCs can protect the $C_R$ clusters from the rest of the galactic tidal field and thereby cause them to retain a significantly higher fraction of stars compared to the $C N$ clusters. For clusters that are super-virialized we find that the $C_R$ clusters have a higher virial ratio compared to the $C_N$ clusters, which is a result of interactions with GMCs. We see no significant difference between the $C_R$ and $C_N$ populations, indicating that over a time period of 200 Myr the effect of the GMCs cannot be detected.

As part of the pilot survey of the Widefield ASKAP L-band Legacy All-sky Survey (WALLABY), high-resolution neutral atomic hydrogen (HI) observations of the dwarf galaxy pair NGC 4532/DDO 137 (WALLABY J123424+062511) have revealed a huge (48 kpc) bridge of gas between the two galaxies, as well as numerous arms and clouds which connect with the even longer (0.5 Mpc) tail of gas previously discovered with the Arecibo telescope. Our modelling suggests that a combination of ram pressure and tidal forces are responsible for the nature of the system. Although the pair lies well outside of the virial radius of the Virgo cluster, ram pressure due to infall through an extensive envelope of hot gas around the cluster is most likely responsible for the HI tail. Over a timescale of 1 Gyr, the predicted electron density ($1.2\times 10^{-5}$ cm$^{-3}$) and infall velocity (880 km s$^{-1}$) are probably sufficient to explain the extensive stripping from the common gaseous envelope of NGC 4532/DDO 137. The ongoing tidal interaction with the Virgo cluster appears to have prevented a rapid merger of the binary pair, with the mutual tidal interaction between the galaxy pair being responsible for raising gas from the outer parts of the galaxy potential wells into the HI bridge and common envelope. The NGC 4532/DDO 137 system mirrors many of the physical features of the Magellanic System, and may lead to a better understanding of that system, as well as casting more light on the relative importance of interaction mechanisms in the outskirts of dynamically young galaxy clusters such as Virgo.

Plasma turbulence cascading from MHD to kinetic scales in the heliospheric plasma is believed to play a key role in coronal heating and fast solar wind acceleration, but the properties of the turbulence remain poorly constrained by observations. Here we compare the ion-scale density fluctuation levels inferred from the properties of solar radio bursts with the magnetic field fluctuation levels obtained through in-situ measurements in the inner heliosphere. We find that the observed magnetic and density fluctuation amplitudes are consistent with excitation by kinetic Alfvén waves and/or KAW structures over broad range of distances from the Sun. We then use the radio diagnostics and the KAW scenario to deduce the radial variation of magnetic fluctuation amplitudes in regions close to the Sun where in-situ measurements cannot be obtained. Further, we calculate the energy cascade rate (plasma heating rate) profile over a region that extends from the low corona ($\sim 0.1$~R$_\odot$) into the heliosphere (out to $\sim 1$~au), and compare it to the energy deposition rate required to drive the solar wind. The cascade rate agrees with the available in-situ measurements and also provides predictions closer than $\sim 10$~R$_\odot$ where in-situ approaches are not available. The results provide unique diagnostics of the ion-scale plasma turbulence amplitude and energy cascade rate spanning over three orders of magnitude in solar distance.

We examine the first three BepiColombo Mercury flybys Using data from the Miniature Ion Precipitation Analyzer (MIPA), an ion mass analyzer in the Search for Exospheric Refilling and Natural Abundances (SERENA) package on the Mercury Planetary Orbiter (MPO) designed to study magnetospheric dynamics. These flybys all passed from dusk to dawn through the nightside equatorial region but were noticeably different from each other. In the first flyby, we observe a low latitude boundary layer and $\sim$1 keV ions near closest approach. For flybys 2 and 3 we see ions up to 14 keV in the same location, including freshly injected precipitating ions inside the loss cone. High time resolution data from flyby 3 show variations consistent with bursty bulk flows 10s long and occurring over $\sim30$s periods, the first such observation in this region. MIPA data demonstrate that high-energy injection processes are an important source of precipitation ions at Mercury.

The convective kissing instability (CKI) is postulated to occur in low mass stars around the fully convective transition. Non-equilibrium $^{3}$He burning leads to the merging of core and envelope convective zones, which causes abrupt decreases in the stellar radius. It has been suggested by van Saders & Pinsonneault (2012) that these effects may be relevant for cataclysmic variables (CVs). We have performed stellar evolution modeling to study the role of the CKI in CV evolution. We find that the CKI has no effect on normal CVs which evolve via magnetic braking and gravitational radiation above the period gap. CKI cycles either do not occur or are abruptly halted once mass transfer begins. If only gravitational radiation is considered, the CKI does occur. The abrupt radius changes can cause detachment phases which produce small period gaps with widths of a few minutes. We describe how the size of the period gaps is controlled by the $^{3}$He profiles of the secondaries. We also discuss how the results of this study apply to the evolution of strong field polars, where the magnetic field of the white dwarf is strong enough to suppress magnetic braking.

Context. In the search for exoplanets using radial velocities (RV), stellar activity has become one of the main limiting factors for detectability. Fortunately, activity-induced RV signals are wavelength-dependent or chromatic, unlike planetary signals. This study exploits the broad spectral coverage provided by the combined use of SOPHIE and SPIRou velocimeters to investigate the chromatic nature of the activity signal of the highly active M dwarf EV Lac. Aims. We aim to understand the origin of the strong wavelength dependence (chromaticity) observed in the RV signal of EV Lac by selecting spectral lines based on physical properties. In particular, we explore the impact of starspots by defining the contrast effect at the level of individual lines. The Zeeman effect is also considered in this study. Methods. SPIRou and SOPHIE spectra were reduced using the line-by-line (LBL) method. We performed custom RV calculations, using groups of spectral lines selected for their sensitivity to either the spot-to-photosphere contrast or the Zeeman effect. The sensi- tivity of each line to the spot is defined using a two-temperature model based on PHOENIX spectra, while Landé factors were used to quantify Zeeman sensitivity. Results. We find that the spectral lines are distributed in two distinct families of contrasts, producing anti-correlated RV signals. This leads to a partial cancellation of the total RV signal, especially at longer wavelengths and provides a natural explanation for the strong chromaticity observed in EV Lac. This sign-reversal effect is demonstrated here, for the first time, on empirical data. Building on this discovery, we propose a new approach to constraining spot temperatures and to mitigating stellar activity. This will open up promising avenues for improving activity corrections and enhancing the detection of exoplanets around active M dwarfs.

The extragalactic background is composed of the emission from all astrophysical sources, both resolved and unresolved, in addition to any diffuse components. In the last decade, there has been significant progress in our understanding of the cosmic history of extragalactic emissions associated with stellar evolution and accretion onto supermassive black holes, largely enabled by the extensive body of multi-wavelength data. The brightness of the extragalactic sky is now measured in photons, neutrinos, and cosmic rays, using observatories on the ground, in the sea, and in the ice, satellites in Earth orbit, and probes at the edge of the solar system. This wealth of disparate data is essential to unraveling the mysteries of the source populations that contribute to the extragalactic background. In this contribution, we present an open database containing the most comprehensive collection of measurements of the extragalactic background spectrum to date. The combination of multi-messenger measurements over 27 frequency decades allows us to estimate the energy density of most extragalactic background components with an uncertainty of less than 30%. We explore the consistency of this cosmic inventory of the observed fields of relativistic particles populating the Universe with the cosmic history of star formation and accretion around supermassive black holes. Models incorporating these cosmic histories, as well as the redshift-dependent luminosity functions of extragalactic sources, currently match the electromagnetic component of the extragalactic background spectrum over 14 frequency decades, from the near UV to sub-TeV gamma rays. The knowledge gained from synthetic population models in the electromagnetic bands may become a crucial tool for understanding the origin of the most energetic extragalactic messengers, neutrinos and ultrahigh-energy cosmic rays.

CARMENES is a dual-channel high-resolution spectrograph at the 3.5 m Calar Alto telescope designed to detect low-mass planets around late-type dwarfs by measuring their radial velocities (RVs). High thermal stability in both the visible (VIS) and near infrared channels is essential to achieve the precision required for these measurements. In particular, stabilising the NIR channel to the millikelvin level, which operates at cryogenic temperatures (140 K), poses significant engineering this http URL CARMENES-PLUS project was initiated to improve the instruments intrinsic RV precision. In this article, we focus on the thermal stability improvements made to the NIR channels cooling system. The NIR cooling system was originally conceived to operate with a discontinuous flow of cryogenic nitrogen gas. As part of CARMENES-PLUS, this was upgraded to a continuous flow configuration. Additional changes included the installation of an automatic vacuum system, a proportional control valve, and a pressure regulation system. These upgrades were designed to reduce thermal fluctuations and enhance long-term stability. The implemented upgrades significantly improved the intrinsic RV precision of the NIR channel. We quantified this improvement using Fabry Perot calibration spectra, obtaining an intrinsic RV precision of 0.67 ms after the interventions, an improvement of nearly 2 ms . We also assessed the stability of the nightly zero points, finding a reduced scatter of 3.9 ms post upgrade, compared to 6.1 ms before. For a sample of slowly rotating stars (vsin i below 2 kms), the median scatter decreased from 8.8 ms to 6.7 ms after the upgrades. These results demonstrate that the thermal control upgrades introduced in CARMENES PLUS have enhanced the NIR channels RV performance, bringing it closer to the VIS channels stability and reinforcing CARMENES capabilities for exoplanet detection around M dwarfs.

K2-19 is a star, slightly smaller than the Sun, that hosts three transiting planets. Two of these, K2-19 b and c, are between the size of Neptune and Saturn and have orbital periods near a 3:2 commensurability, and exhibit strong transit-timing variations (TTVs). A previous TTV analysis reported moderate eccentricities of $\approx0.20 \pm0.03$ for the two planets, but such high values would imply rapid orbital decay for the innermost planet d. Here, we present an updated analysis that includes eight new transit times from TESS, which extends the time baseline from three years to a decade, and employ a gradient-aware TTV modeling code. We confirm that the system resides in resonance with a small libration amplitude, but find a broader constraints on eccentricity that range from a few percent up to 0.2. These revised eccentricities alleviate previous concerns regarding rapid tidal circularization and support the long-term dynamical stability of the system.

Context. In a previous paper (Afify et al. 2024), we have investigated the stability threshold of the ion-ion acoustic instability (IIAI) in parameter regimes compatible with recent Parker Solar Probe (PSP, (Fox et al. 2016)) observations, in the presence of a Maxwellian electron distribution. We found that observed parameters are close to the instability threshold, but IIAI requires a higher electron temperature than observed. Aims. As electron distributions in the solar wind present clear non-Maxwellian features, we investigate here if deviations from the Maxwellian distribution could explain the observed IIAI. We address specifically the kappa ( $\kappa$ ) and core-strahl distributions for the electrons. Methods. We perform analytical studies and kinetic simulations using a Vlasov-Poisson code in a parameter regime relevant to PSP observations. The simulated growth rates are validated against kinetic theory. Results. We show that the IIAI threshold changes in the presence of $\kappa$ or core-strahl electron distributions, but not significantly. In the latter case, the expression of an effective temperature for an equivalent Maxwellian electron distribution given in Jones et al. (1975) is confirmed by simulations. Such an effective temperature could simplify stability assessment of future observations.

We present gas-phase abundances of carbon (C), $\alpha$-elements (O, Ne, Si, and Ar) and iron (Fe) obtained from stacked spectra of high-$z$ star-forming galaxies with the deep Near Infrared Spectrograph medium-resolution data from the James Webb Space Telescope Advanced Deep Extragalactic Survey. Our 564 sources at $z=4$--7 have a median stellar mass of $\log(M_{*}/M_{\odot})=8.46$ and a median star-formation rate of $\log(\mathrm{SFR}/M_{\odot}\,\mathrm{yr^{-1}})=0.30$, placing them close to the star-formation main sequence. We find that the stacked spectrum of all our 564 sources has relatively low [C/O]$=-0.70$, moderate [Ne/O]$=-0.09$, and low [Ar/O]$=-0.28$ values at a low gas-phase metallicity of $12+\log(\mathrm{O/H})=7.71$ ($Z\sim 0.1~Z_\odot$), suggesting dominant yields of core-collapse supernovae evolved from massive stars. The detection of a weak SiIII] emission line in our stacked spectrum provides a silicon-to-oxygen abundance ratio of [Si/O]$=-0.63$, which is lower than that of stars in the Milky Way disc and lower than expected by chemical evolution models, suggesting silicon depletion onto dust grains. Likewise, this Si/O value is lower than that we newly derive for two individual $z>6$ galaxies (GN-z11 and RXCJ2248) with negligible dust attenuation. By performing spectral stacking in bins of $M_{*}$, SFR, specific SFR (sSFR), and ultra-violet (UV) continuum slope $\beta_{\mathrm{UV}}$, we identify [FeIII] line detections in the high-sSFR bin and the blue-$\beta_{\mathrm{UV}}$ bin, both of which exhibit supersolar Fe/O ratios, while their C/O, Ar/O, and Si/O ratios are comparable to those of the all-sources stack. Our findings support a chemically young gas composition with rapid dust depletion in the general population of high-$z$ star-forming galaxies, while raising the possibility of anomalous, selective Fe/O enhancement at the very early epoch of star formation.

We investigate how the star formation activity of galaxies depends on their position within the cosmic web using the SIMBA cosmological simulation from redshift $z=3$ to $z=0$. While previous studies found that galaxies closer to filaments tend to be more massive and quenched, it remained unclear whether these trends reflect intrinsic environmental effects or changes in the galaxy population mix. To address this, we focus exclusively on star-forming galaxies, robustly selected using both the specific star formation rate (sSFR) and gas depletion timescale criteria, in order to isolate the direct impact of the cosmic web on star-forming galaxies. We reconstruct the 3D cosmic web skeleton using DisPerSE and compute each galaxy's distance to its nearest filament. After removing mass dependencies, we examine deviations in star formation rate (SFR), sSFR, molecular and atomic gas depletion timescales, and gas fractions as a function of this distance. We find a clear and redshift-dependent modulation of star formation with filament proximity: at high redshift ($z \gtrsim 2$), galaxies closer to filaments show enhanced SFR and gas accretion, reflecting efficient filament-fed growth. At $z=0$, we observe a V-shaped trend in the sSFR and depletion timescales, with minima at intermediate distances ($\sim 0.25$ cMpc) and a surprising upturn very close to the filament cores, suggesting a resumed accretion in the densest environments. These effects are not driven by mergers and are primarily associated with satellite galaxies at low redshift. Our results demonstrate that large-scale cosmic web proximity modulates star formation in star-forming galaxies through a combination of gas supply regulation and environmental processing, with different mechanisms dominating across cosmic time.

We present integral field spectroscopic observations of 75 strong gravitational lens candidates identified with a residual neural network in the DESI Legacy Imaging Surveys, obtained with the Multi Unit Spectroscopic Explorer (MUSE) on the ESO's Very Large Telescope. These observations are part of an ongoing effort to build a large, spectroscopically confirmed sample of strong lensing systems for studies on dark matter, galaxy structure, and cosmology. Our MUSE program targets both lens and source redshifts, with particular emphasis on southern hemisphere systems. MUSE's wide spectral coverage and integral field capability allow for efficient identification of multiple sources, lens environments, and weak spectral features. Redshifts for lenses and sources were obtained via manual identification of spectral features in extracted 1D spectra. Our dataset includes systems with complex configurations, such as multiple source planes and group or cluster-scale environments. We extracted and analyzed 185 spectra, successfully determining both the lens and the source redshifts for 48 gravitational lens systems. For an additional 21 targets, we measured the redshifts of the lenses but were unable to determine the redshifts of the background sources. Six targets were confirmed to not be gravitational lenses. The results presented here complement space-based imaging from our HST SNAPshot program and spectroscopic follow-up with DESI and Keck, and have lasting legacy value for identifying interesting high-redshift sources and complex lensing configurations.

We present spectroscopic data of strong lenses and their source galaxies using the Keck Near-Infrared Echellette Spectrometer (NIRES) and the Dark Energy Spectroscopic Instrument (DESI), providing redshifts necessary for nearly all strong-lensing applications with these systems, especially the extraction of physical parameters from lensing modeling. These strong lenses were found in the DESI Legacy Imaging Surveys using Residual Neural Networks (ResNet) and followed up by our Hubble Space Telescope program, with all systems displaying unambiguous lensed arcs. With NIRES, we target eight lensed sources at redshifts difficult to measure in the optical range and determine the source redshifts for six, between $z_s$ = 1.675 and 3.332. DESI observed one of the remaining source redshifts, as well as an additional source redshift within the six systems. The two systems with non-detections by NIRES were observed for a considerably shorter 600s at high airmass. Combining NIRES infrared spectroscopy with optical spectroscopy from our DESI Strong Lensing Secondary Target Program, these results provide the complete lens and source redshifts for six systems, a resource for refining automated strong lens searches in future deep- and wide-field imaging surveys and addressing a range of questions in astrophysics and cosmology.

We present the Dark Energy Spectroscopic Instrument (DESI) Strong Lensing Secondary Target Program. This is a spectroscopic follow-up program for strong gravitational lens candidates found in the DESI Legacy Imaging Surveys footprint. Spectroscopic redshifts for the lenses and lensed source are crucial for lens modeling to obtain physical parameters. The spectroscopic catalog in this paper consists of 73 candidate systems from the DESI Early Data Release (EDR). We have confirmed 20 strong lensing systems and determined four to not be lenses. For the remaining systems, more spectroscopic data from ongoing and future observations will be presented in future publications. We discuss the implications of our results for lens searches with neural networks in existing and future imaging surveys as well as for lens modeling. This Strong Lensing Secondary Target Program is part of the DESI Strong Lens Foundry project, and this is Paper II of a series on this project.

Inspired by an earlier idea of Mashhoon, who suggested to relate the discrete quasinormal resonant modes of a black hole to the bound-state resonances of the corresponding inverted black-hole potential, Völkel [Phys. Rev. Lett. {\bf 134}, 241401 (2025)] has recently computed numerically, for the first time, the bound-state energy spectrum of the inverted Schwarzschild potential. Motivated by this intriguing work, in the present work we use {\it analytical} techniques in order to explore the physical and mathematical properties of the Schwarzschild bound-state resonances. In particular, we derive closed-form compact analytical formulas for the infinite spectrum $\{E_n\}_{n=0}^{n=\infty}$ of energy eigenvalues that characterize the inverted (binding) black-hole potential. Interestingly, it is explicitly shown that our analytically derived energy spectrum of the black-hole inverted potential agrees remarkably well with the corresponding numerical data that recently appeared in the physics literature.

Cosmic rays interact with nuclei in the Earth's atmosphere to produce extensive air showers, which give rise to the atmospheric muon flux. Temperature fluctuations in the atmosphere influence the rate of muons measured in deep underground experiments. This contribution presents predictions of the daily muon flux at a depth of 2000 m.w.e., calculated using MUTE, a software tool which combines MCEq, a numerical solver of the matrix cascade equations in the atmosphere, with PROPOSAL, a propagation code for leptons in matter. The flux estimates are obtained assuming different cosmic-ray flux and hadronic interaction models. The results are compared to previous approaches, based on different methods, to calculate seasonal variations of atmospheric muons in deep underground detectors.

The continuum emission from the hot and ionized inner regions of a supermassive black hole (SMBH) accretion disk that is strongly lensed by the light-ring (i.e., the unstable photon orbit), is always superimposed on that of the locally emitting plasma near the innermost stable circular orbit (ISCO), masking strong-gravity effects and making their study difficult. A cleaner image of the light-ring against a non-luminous background, not affected by the emission and all the dynamical effects taking place near the ISCO, would thus be preferable. A more distant SMBH illumination source that could accommodate this can be provided by the unique spectral lines emitted by the cooler parts of the accretion disk, the so-called Broad Line Region (BLR). Spectral line emission from the transitional region between the inner disk and the outer BLR may be ideal for obtaining a cleaner image of the light-ring, and better suited for strong gravity tests. A crucial first order effect of a BLR spectral line illumination of the SMBHs in galactic centers, and a possible smoking gun signal of strong SMBH lensing, will be an Einstein ring, whose presence could be evident even in unresolved sources where only the total line profile can be acquired. In resolved sources, the combination of information from the image and the spectrum can even facilitate the measurement of the mass of the SMBH.

SMBHs at the centers of galaxies, illuminated by their accretion disks, can reveal valuable information on BH spacetimes via their shadows, which can be used for strong-gravity tests. However, the continuum emission from their highly turbulent hot plasma is expected to be strongly time-varying and with very inhomogeneous brightness. This can mask important SMBH-related effects, like the appearance of the light-ring, rendering them ineffective as probes of strong gravitational lensing physics. Besides being an inhomogeneous and strongly time-varying ''illuminator'', the hot plasma emission extends all the way to the ISCO. This then leads to the superposition of the strongly-lensed radiation from the area of the light-ring to the continuum emission from the ISCO, effectively making gravitational lensing physics hard to separate from accretion disk Astrophysics. These problems could be overcome if one utilizes the spectral line radiation field emanating from the cooler parts of the extended accretion disk, the so-called BLR, and especially its expected neutral phase, as a more distant, but still adequately strong SMBH illuminator, typically found at $r\sim (10^2-10^4)\, R_s$. This kind of illumination can provide a cleaner image of the light-ring region, and thus allow more information on the spacetime geometry around the SMBH to be obtained. Here, we examine some of the benefits of such an illumination in discerning strong-gravity physics near SMBHs and their observability. We expand on the fact that such emission can provide a smoking gun signal of lensing, in the form of an Einstein ring. To first order, the imaging of the Einstein ring and its spectroscopic signature can facilitate the measurement of the SMBH mass, while the second order effects associated with the light-ring can constrain the SMBH spin, and even identify deviations from the Kerr spacetime.

We analyze the dynamics of charged test particles in a singular, horizonless spacetime arising as the massless limit of a charged wormhole in the Einstein--Maxwell--Scalar framework. The geometry, sustained solely by an electric charge \(Q\), features an infinite sequence of curvature singularity shells, with the outermost at \(r_\ast = \frac{2|Q|}{\pi}\) acting as a hard boundary for nonradial motion, while radial trajectories can access it depending on the particle's charge-to-mass ratio \(\frac{|q|}{m}\). Exploiting exact first integrals, we construct the effective potential and obtain circular orbit radii, radial epicyclic frequencies, and azimuthal precession rates. In the weak-field limit (\(r \gg |Q|\)), the motion reduces to a Coulombic system with small curvature-induced retrograde precession. At large radii, the dynamics maps to a hydrogenic system, with curvature corrections inducing perturbative energy shifts. Approaching \(r_\ast\), the potential diverges, producing hard-wall confinement. Curvature corrections also modify the canonical thermodynamics, raising energies and slightly altering entropy and heat capacity. Our results characterize the transition from Newtonian-like orbits to strongly confined, curvature-dominated dynamics.

Recent non-modal analyses have uncovered spectral instabilities in the quasinormal-mode spectrum of black holes; a phenomenon that intriguingly extends to spherically-symmetric exotic compact objects. These results point to a sensitivity of the spectrum with potentially far-reaching implications for black-hole spectroscopy. At the same time, growing attention has turned to astrophysical environments around compact objects and their role in shaping gravitational-wave astrophysics. In this work, we establish a direct link between spectral instabilities and environmental effects by modeling matter as a localized bump outside the light ring of a spectrally-unstable exotic compact object with a purely reflective surface. We find that while such environments can destabilize the fundamental quasinormal modes of loosely-compact exotic objects, the fundamental modes of ultra-compact horizonless objects remain remarkably robust. In contrast, overtones are shown to develop spectral instabilities in the presence of the bump. By tracking both interior modes, trapped between the light ring and the surface of the exotic compact object, and exterior modes, confined between the bump and the light ring, we uncover an overtaking instability in which ``unperturbed'' exterior overtones metamorphose into ``perturbed'' fundamental modes as the bump moves outward. Finally, we demonstrate that environmental effects, while capable of further amplifying spectral instabilities, cannot induce next-to-leading-order perturbations strong enough to trigger a modal instability.

We study the viability of light thermal dark matter (DM) in sub-GeV mass range in view of the stringent new DAMIC-M limits on DM-electron scattering. Considering a Dirac fermion singlet DM charged under a new Abelian gauge symmetry $U(1)$, we outline two possibilities: (i) family non-universal $U(1)$ gauge coupling with resonantly enhanced DM annihilation into standard model (SM) fermions and (ii) family universal dark $U(1)$ gauge symmetry where relic is set by DM annihilation into light gauge bosons. As an illustrative example of the first class of models, we consider a gauged $L_\mu-L_\tau$ extension of the SM having interesting detection prospects at several experiments. While both of these class of models lead to observed DM relic and consistency with DAMIC-M together with other experimental limits, the second class of models also lead to strong DM self-interactions, potentially solving the small-scale structure issues of cold dark matter. While a vast part of the parameter space in both the models is already ruled out, the current allowed region of parameter space can be further probed at ongoing or future experiments keeping the models testable.

We investigate, for the first time, universal relations for anisotropic dark energy stars. The stars are modeled with the modified Chaplygin equation of state and the Bowers-Liang prescription for anisotropy, and their global properties and $f$-mode frequencies are computed using the modified relativistic Hartle-Thorne slow rotation and Cowling approximations. We find that relations among moment of inertia, tidal deformability, quadrupole moment and $f$-mode frequency exhibit universality, with deviations limited to $1-10\%$, in close agreement with other compact star models. Using tidal deformability constraints from GW170817 and GW190814, we obtain astrophysical limits on canonical properties of dark energy stars. For positive anisotropy strength, the radius of a $1.4M_\odot$ star is constrained to $R_{1.4}=8.93^{1.88}_{1.40}$ km (GW170817) and $10.92^{+0.71}_{-0.54}$ km (GW190814), consistent with observational bounds. The corresponding $f$-mode frequencies are constrained to $3.257^{+0.450}_{-0.537}$ kHz and $2.692^{+0.137}_{-0.157}$ kHz. Further, applying Pearson correlation analysis for the first time to anisotropic compact stars, we obtained the coefficients between various stellar attributes of dark energy stars and we show that the Chaplygin parameter $B$ correlates strongly with the $f$-mode frequency, with positive anisotropy strengthening while negative anisotropy weakening the correlation strength. These results establish that universal relations extend to anisotropic dark energy stars and can be directly tested with present and future gravitational-wave observations.

Using a relativistic mean-field model calibrated to finite-nucleus observables and bulk properties of dense nuclear matter, we investigate hyperonic neutron-star matter within an SU(3) flavor-symmetry scheme. To retain SU(6)-based couplings within SU(3) flavor symmetry, we add a quartic $\phi$ self-interaction and $\phi$-$\rho$ mixing. We demonstrate the roles of $\alpha_{v}$ ($F/(F+D)$ ratio), $\theta_{v}$ (mixing angle), and $z_{v}$ (singlet-to-octet coupling ratio) in SU(3)-invariant vector-meson couplings. It is found that $z_{v}$ predominantly controls the maximum mass of a neutron star, and $2M_{\odot}$ neutron stars can be supported for $z_{v}\le0.15$. The $\alpha_{v}$ also helps sustain large masses, whereas $\theta_{v}$ has a smaller effect on neutron-star properties. This SU(3) framework reconciles nuclear and astrophysical constraints, and offers a plausible resolution to the hyperon puzzle.

We show that it is possible to locate the few places on the body of an airplane, while it is flying through high clouds, from which broad-band, pulsed, radiation is emitted at Very High Frequency (VHF) radio frequencies. This serendipitous discovery was made whilst imaging a lightning flash using the Low-Frequency Array (LOFAR). This observation provides insights into the way the airplane sheds the electrical charge it acquires when flying through clouds. Furthermore, this observation allowed us to test and improve the precision and accuracy for our lightning observation techniques. Our new results indicate that with the improved procedure the location precision for strong pulses is better than 50~cm, with the orientation of linear polarization being accurate to within 25$^\circ$. For the present case of a Boeing 777-300ER, VHF emissions were observed exclusively associated with the two engines, as well as a specific spot on the tail. Despite the aircraft flying through clouds at an altitude of 8~km, we did not detect any emissions from electrostatic wicks.

We study collective excitations in a relativistic collisionless plasma composed of massless fermions subject to an external magnetic field. We include dynamical electromagnetism and fluctuations of the chiral charge, while maintaining a vanishing net chiral charge. Within the framework of chiral kinetic theory, we find that the chiral anomaly gives a correction to the dispersion relation of the transverse mode. In a strong magnetic field, we also show that the collective mode has a gap using the lowest Landau level approximation. We discuss the anomalous correction in the context of neutron star phenomenology.

With the rapid increase in the number of artificial satellites, astronomical imaging is experiencing growing interference. When these satellites reflect sunlight, they produce streak-like artifacts in photometry images. Such satellite trails can introduce false sources and cause significant photometric errors. As a result, accurately identifying the positions of satellite trails in observational data has become essential. In this work, we propose a satellite trail detection model that combines the U-Net deep neural network for image segmentation with the Line Segment Detector (LSD) algorithm. The model is trained on 375 simulated images of satellite trails, generated using data from the Mini-SiTian Array. Experimental results show that for trails with a signal-to-noise ratio (SNR) greater than 3, the detection rate exceeds 99. Additionally, when applied to real observational data from the Mini-SiTian Array, the model achieves a recall of 79.57 and a precision of 74.56.

We present a phenomenological study of rotating, charged black holes in Einstein gravity coupled to a traceless (conformal) matter sector formed by ModMax nonlinear electrodynamics and a Kalb-Ramond two-form that spontaneously breaks local Lorentz symmetry. Starting from a family of obtained static, Schwarzschild-like solutions with a traceless Kalb-Ramond sector, we construct the stationary, axisymmetric counterpart via the Newman-Janis algorithm. The resulting Newman-Kerr-like metric depends on four intrinsic parameters: the electric charge $Q$, the ModMax nonlinearity $\gamma$, the Lorentz-violation amplitude $\ell$ and the spin $a$. We analyze horizon structure and separatrices in parameter space, derive the null geodesic equations and obtain the photon capture boundary that defines the black hole shadow. Using ray-tracing, we compute shadow silhouettes and a suite of shadow observables (areal radius, characteristic radius $R_s$, distortion $\delta$, oblateness $D$) and show how $\gamma$ and $\ell$ produce qualitatively distinct effects: $\gamma$ acts as a screening factor for the electromagnetic imprint, while $\ell$ introduces angular-dependent metric rescalings that deform shadow shape beyond simple size rescaling. We confront model predictions with EHT angular-radius measurements for M87$^*$ and Sgr A$^*$ and derive conservative bounds on the combinations of $(Q,\gamma,\ell,a)$. Our results identify an effective charge combination $Q_{\rm eff}\simeq e^{-\gamma}Q^{2}/(1-\ell)^{2}$ and demonstrate that modest $Q_{\rm eff}$ remains compatible with current EHT images while large $Q_{\rm eff}$ is progressively disfavored.

We present a new type of Scalar-Vector-Tensor (SVT) theories with higher derivatives of all the fields in the action, but with second order equations of motion. The higher derivative vector field is invariant under a U(1) gauge transformation and the Scalar-Tensor sector corresponds to Horndeski theory. We also present a subclass of these SVT theories with 8 free functions of $\pi$ and $X$ where the speed of the tensor and vector modes is exactly the same. In particular, the Horndeski functions $G_4(\pi,X)$ and $G_5(\pi)$ remain free, while the speed of the vector modes tracks the speed of the tensor modes. Additionally, the vector sector retains freedom through the four new functions. All the theories here shown are a generalization of the Kaluza-Klein reduction of 5D Horndeski theory, sharing the main properties in cosmology, but including new free scalar functions in the Lagrangian.

Axions and axion-like particles are ubiquitous in extensions of the Standard Model and offer a unifying perspective on open problems in cosmology. Depending on their mass and interactions, axions can act as dark matter, drive cosmic acceleration as dark energy, or contribute to the relativistic background as dark radiation. Motivated by the plenary talk at TAUP 2025, this proceeding reviews the phenomenology of light bosons in the early and late Universe, with a focus on the theoretical foundations, observational signatures, and experimental prospects.

The nature of turbulence at sub-electron scales has remained an open question, central to understanding how electrons are heated in the solar wind. This is primarily because spacecraft measurements have been limited to magnetic field fluctuations alone. We resolve this by deriving new high-resolution density fluctuations from spacecraft potential measurements of Parker Solar Probe resolving scales smaller than the electron gyro-radius ($\rho_e$). A systematic comparison of the density and magnetic spectra shows that both steepen near the electron scales. Notably, the density spectrum exhibits slopes close to $-10/3$, while the magnetic spectrum becomes consistently steeper than the density spectrum at scales smaller than $\rho_e$, indicating that the turbulence becomes electrostatic. These results are consistent with theoretical predictions of an electron entropy cascade, which may explain the irreversible dissipation of turbulent energy at sub-$\rho_e$ scales.

We present strong evidence for dynamical dark energy challenging the $\Lambda$CDM model. Several dark energy models are explored, including $\omega_0\omega_a$CDM, logarithmic, Exponential, JBP, and BA, along with non-flat cosmologies accounting for potential spatial curvature. Our analysis supports a flat Universe ($\Omega_k \approx 0$). Using the Metropolis-Hastings MCMC algorithm, we analyze data from BAO of DESI DR2, Type Ia Supernovae, and CMB to constrain model parameters. We find strong evidence that $\omega \neq -1$, with deviations from $\Lambda$CDM favoring dynamical dark energy consistent with the Quintom-B scenario ($\omega_0 > -1$, $\omega_a < 0$, and $\omega_0 + \omega_a < -1$). We also derive upper bounds on $\sum m_\nu$ from CMB + DESI DR2. For $\Lambda$CDM we find $\sum m_\nu < 0.066~\text{eV}$, while for $\omega$CDM it is $\sum m_\nu < 0.075~\text{eV}$. In o$\Lambda$CDM and o$\omega$CDM the limits are $\sum m_\nu < 0.263~\text{eV}$ and $\sum m_\nu < 0.520~\text{eV}$, respectively. For other models, including $\omega_0\omega_a$CDM, Logarithmic, Exponential, JBP, BA, and GEDE, the upper limits range from $< 0.043~\text{eV}$ to $< 0.127~\text{eV}$. Constraints on the effective number of relativistic species, $N_{\text{eff}}$, remain consistent with the standard value $N_{\text{eff}} = 3.044$ for all models. Bayesian evidence shows that combining DES-SN5Y and Union3 SNe Ia with CMB + DESI DR2 reveals deviations from $\Lambda$CDM. Finally, while no model reaches the $5\sigma$ threshold, some show $> 3\sigma$ tensions with DES-SN5YR or Union3, hinting at cracks in the cosmological constant $\Lambda$.

We propose a new model to explain the KM3NeT neutrino event through a low reheating scenario with a suppression in the GW spectrum originating from cosmic string networks. To achieve this, we extend the SM gauge sector by an abelian gauge symmetry and a singlet scalar. Once the abelian gauge symmetry spontaneously breaks, the extra gauge boson acquires mass and becomes a suitable Dark Matter (DM) candidate. Due to the kinetic mixing with the hypercharge gauge group, DM can decay into SM particles. To explain the KM3NeT signal, we need $\mathcal{O}(100)$ PeV DM, which can be produced in the correct order of DM density in a low reheating scenario. In this scenario, the overabundance issue of heavy DM can be tackled by diluting its abundance through the continuous injection of entropy when the matter-like inflaton decays into the SM bath. Using the low reheating scenario, we can obtain the correct value of DM density both for freeze-out and freeze-in mechanisms for super-heavy DM. Moreover, we have studied the Gravitational Waves (GWs) produced from cosmic strings, which fall within the detectable range of future proposed GW experiments. Additionally, the dominance of a quadratic inflaton potential before the reheating temperature changes the temperature-scale factor relation, which suppresses the GW spectrum at higher frequencies. Choosing an arbitrarily low reheating temperature provides only a tiny fraction of the DM density due to dilution from entropy injection. This fraction of the vector DM suggests that only the extragalactic contribution is relevant in the KM3NeT event because DM lifetime is shorter than the age of the Universe.

Multifield models, arising from multiple scalars interacting with gravity, provide a rich theoretical framework for addressing fundamental problems in modern cosmology. A key role in this regard is played by the so called rapid turn regime, which is characterized by background solutions with strongly non-geodesic field-space trajectories. We review the implications of this regime for a number of problems relevant for cosmological inflation, dark matter and dark energy. We focus, in more detail, on a class of exact rapid-turn solutions that give a model of dynamical dark energy. In this model, the sound speed of the dark energy perturbations is reduced compared to the speed of light, which leads to observational differences from a cosmological constant even for an equation-of-state parameter very close to -1. Furthermore, this model holds promise for the simultaneous alleviation of two prominent cosmological tensions.

Uranus and Neptune are the least explored planets in the Solar System. A key question regarding the two planets is the similarity of their observed flows despite the great differences in their obliquity and internal heating. To answer this fundamental question and understand the ice giants atmospheric circulation, we developed a new general circulation model (GCM). This tool will also be key to facilitating the success of future missions to the ice giants, for which atmospheric flows will be a measurable quantity. Past GCMs for the ice giants have struggled to reproduce the observed winds on Uranus and Neptune. Using our idealized GCM, we systematically explored how the zonal wind and meridional circulation respond to different model and physical parameters; our main focus was on the depth of the domain. We show that in cases where the bottom layer of the model is deep enough, the simulated flow is independent of the meridional structure of the forcing temperature, indicating that dynamical processes, and not the imposed thermal forcing, are the dominant drivers of the circulation and the thermal structure. A momentum balance analysis further shows that meridional and vertical eddy momentum flux convergence are both central to maintaining the circulation. These results provide a physical explanation for the similarity of the flow on Uranus and Neptune although their solar and internal forcing are significantly different. The modeling framework developed in this study can serve as a foundation for the development of more comprehensive GCMs of the ice giants and help guide the interpretation of future mission data.

The observed matter-antimatter asymmetry of the Universe remains a fundamental challenge in modern physics. In this work, we explore gravitational baryogenesis within the framework of $f(T,L_m)$ gravity, where the gravitational Lagrangian depends on both the torsion scalar $T$ and the matter Lagrangian $L_m$. We consider three representative models and examine their ability to generate the observed baryon-to-entropy ratio. Our analysis shows that couplings involving both torsion and the matter Lagrangian, $\partial_\mu(-T-\frac{L_m}{L_0})$, can successfully account for the baryon asymmetry for decoupling temperatures in the range $10^{12}$-$10^{14}\,\text{GeV}$, while remaining consistent with small deviations from General Relativity. These results highlight the capacity of $f(T,L_m)$ gravity to provide novel mechanisms for baryogenesis, demonstrating that the interplay between torsion and matter-sector contributions can naturally generate the observed asymmetry. The framework also remains compatible with late-time cosmological evolution, offering a unified setting for early- and late-time dynamics.

The DECi-hertz Interferometer Gravitational-wave Observatory (DECIGO) is a planned space-based, next-generation gravitational wave detector aimed at observing primordial gravitational waves originating form cosmic inflation. This work focuses on reducing the quantum noise, in the instrument's observation band of 0.1 to 10 Hz, by employing optical springs and a homodyne detection scheme. Although detuning 1000\,km long arm cavities was previously considered ineffective due to quantum state degradation from diffraction losses, we revisit this problem by formulating a new, rigorous model for quantum state of light by accounting for the vacuum state mixing as a result of diffraction losses. This work shows that high sensitivities can be achieved by employing optimal configurations of optical springs and homodyne detection schemes even with diffraction losses. These improvements alone are still not sufficient to achieve sensitivities to detect primordial gravitational waves as other technical noises limit further improvement.

In the momentarily comoving frame of a cosmological fluid, the determinant of the energy-momentum tensor (EMT) is highly sensitive to its pressure. This component is significant during radiation-dominated epochs, and becomes naturally negligible as the universe transitions to the matter-dominated era. Here, we investigate the cosmological consequences of gravity sourced by the determinant of the EMT. Unlike Azri and Nasri, Phys. Lett. B 836, 137626 (2023), we consider the most general case in which the second derivative of the perfect-fluid Lagrangian does not vanish. We derive the gravitational field equations for the general power-law case and examine the cosmological implications of the scale-independent model characterized by dimensionless couplings to photons and neutrinos. We show that, unlike various theories based on the EMT, the present setup, which leads to an enhanced gravitational effects of radiation, does not alter the time evolution of the energy density of particle species. Furthermore, we confront the model with the predictions of primordial nucleosynthesis, and discuss its potential to alleviate the Hubble tension by reducing the sound horizon. The radiation-gravity couplings we propose here are expected to yield testable cosmological and astrophysical signatures, probing whether gravity distinguishes between relativistic and nonrelativistic species in the early universe.

We determine exact analytic three-parameter expressions for the non-rotating metric, describing a Taub-NUT-like black hole (BH), and its associated bumblebee field that are solutions to the Einstein-bumblebee gravity. We construct a consistence thermodynamics for the Taub-NUT-like BH and determine its thermodynamic topological class. The Lorentz symmetry breaking affects the mass and temperature of the BH but does not its thermodynamic topological classification.