Papers for Monday, Dec 01 2025

The direct imaging of black holes by the Event Horizon Telescope (EHT) enables precision tests of gravity in the strong-field regime. We investigate the cosmological evolution and optical appearance of black holes in 4D Einstein-Gauss-Bonnet (EGB) gravity coupled with Kaniadakis Holographic Dark Energy (KHDE). Utilizing Cosmic Chronometers (CC) and Type Ia Supernovae (SNIa) datasets, we constrain model parameters via Markov Chain Monte Carlo (MCMC) analysis. Results indicate that the late-time universe statistically favors a phantom-like equation of state ($c \approx 0.704$). Regarding the EGB coupling $\alpha$, although data favor a positive value, the parameter space permits negative values down to a theoretical stability cut-off at $\alpha \approx -0.03$. While the best-fit suggests deviation, results remain consistent with General Relativity ($\alpha=0$) within the $2\sigma$ confidence level. Based on these constraints, we model the secular mass accretion history (treating accretion efficiency as a phenomenological constant) and compute the shadow radius evolution. We find that in a realistic dispersive plasma environment, refractive effects significantly mask intrinsic gravitational and dark energy signatures, causing global shadow shrinkage. Nevertheless, a characteristic systematic intrinsic deviation of $\sim 1\%$--$1.5\%$ (under a conservative accretion scenario) persists at redshifts $z \lesssim 1.5$ relative to standard $\Lambda$CDM predictions. These findings suggest that despite environmental dominance, precise statistical analyses of shadow populations could disentangle these subtle dynamic dark energy signals from the standard cosmological paradigm.

We investigated an isolated, globule-shaped object (0.37x0.11 pc), located near the centre of the Cygnus OB2 cluster and named proplyd #7 in optical observations. The source can be a massive star (with or without disc) with a HII region or a G-type T Tauri star with a photo-evaporating disc, embedded in a molecular envelope. We obtained a map of the OI line at 63 micron with 6" angular resolution and employed archival data of the CII 158 micron line (14" resolution), using the upGREAT heterodyne receiver aboard SOFIA. We also collected IRAM 30m CO data at 1mm (11" resolution). All the lines were detected across the whole object. The peak integrated OI emission of ~5 K km/s is located ~10" west of an embedded YSO. The OI and CII data near the source show bulk emission at ~11 km/s and a line wing at ~13 km/s, while the 12CO 2-1 data reveal additional blue-shifted high-velocity emission. The KOSMA-tau PDR model can explain the emissions in the tail with a low external UV field (<350 Go, mostly consistent with our UV field estimates), but not at the location of the YSO. There, the high line intensities and increased line widths for all lines and a possible bipolar CO outflow suggest the presence of a protostellar disc. However, the existence of a thermal HII region, revealed by combining existing and new radio continuum data, points towards a massive star - and not a T Tauri-type one. We derived molecular and atomic gas masses of ~20 Msun and a few Msun, respectively. The photo-evaporation (only considering external illumination) lifetime of 1.6x10^5 yrs is shorter than the free-fall lifetime of 5.2x10^5 yrs; thus, we find that proplyd #7 might not have had the time to produce many more stars.

We investigate the formation of multiple spiral modes in Milky Way-like disk-halo systems without explicitly exciting perturbations. We explore how numerical resolution, the level of local disk stability, and the presence of a live halo influence both the initial appearance and the subsequent evolution of these modes. To characterize spiral structure, we compute Fourier amplitudes for modes $m=1$-$6$. In marginally unstable, lower-resolution disks ($N_\star=5\times10^6$, $N_{\rm DM}=1.14\times10^7$), faint features appear within the first $0.5$ Gyr due to numerical noise, in contrast to high-resolution models where perturbations emerge later. Across all sufficiently resolved, live-halo models with $m_{\rm DM}/m_\star \le 10$, the spirals exhibit a cascading sequence in both mode number and radius: higher-$m$ modes form and decay first, followed by the delayed emergence of lower-$m$ modes, with an inward drift of the activity's epicenter. This behavior reflects a combination of local swing amplification, which explains the initial growth of short-wavelength modes, and interference between coexisting long-lived spiral modes, which accounts for the recurrent short-timescale amplitude modulations. In contrast, models with a fixed halo potential or coarse halo resolution ($N_{\rm DM}=1.14\times10^6$ and $m_{\rm DM}/m_\star=100$) show strong early spirals but lack this coherent cascading behavior, owing to excessive shot noise and insufficient halo responsiveness. The $m=3$ mode plays a transitional role, marking the onset of angular-momentum transport in the inner disk that precedes bar formation, a process absent in fixed-potential models. Our results show that a live halo with appropriate mass resolution provides the gravitational response needed to sustain and regenerate multi-mode spiral structure, even though the total angular-momentum exchange remains small.

Internal magnetic fields are an elusive component of stellar structure. However, they can play an important role in stellar structure and evolution models through efficient angular momentum transport and their impact on internal mixing. We strive to explain the 9 components of one frequency multiplet, identified as a low-order quadrupole gravity mode detected in the light curve of the beta Cep pulsator HD 192575 assembled by the Transiting Exoplanet Survey Satellite (TESS). We update the frequencies of the quadrupole mode under investigation using a standard prewhitening method applied to the 1951.46 d TESS light curve, showing that an internal magnetic field is required to simultaneously explain all 9 components. We implement theoretical pulsation computations applicable to the low-order modes of a beta Cep pulsator including the Coriolis force, as well as a magnetic field that is misaligned with respect to the rotation axis. We apply the theoretical description to perform asteroseismic modelling of the amplitudes and frequencies in the multiplet of the quadrupole g-mode of this evolved beta Cep star. Pulsation predictions based on the measured internal rotation frequency of the star cannot explain the observed 9-component frequency splittings of the quadrupole low-order gravity mode. By contrast, we show that the combined effect of the Coriolis force caused by the near-core rotation with a period of about 5.3 d and the Lorentz force due to an internal inclined magnetic field with a maximum strength of around 24 kG does provide a proper explanation of the 9 multiplet frequencies and their relative amplitudes. Given the stellar mass of about 12 solar masses, this work presents the detection and magneto-gravito-asteroseismic modelling of a stable internal magnetic field buried inside an evolved rotating supernova progenitor.

Despite being only the 19th most abundant element in the interstellar medium, chlorine's reactivity and volatility give rise to a unique interstellar chemistry, favouring the formation of several chlorine-bearing hydrides. Further, the $^{35}\text{Cl}/ ^{37}$Cl ratio probes nucleosynthesis across the Galaxy. Yet, studies of Cl-bearing molecules have remained limited to a few sightlines due to observational challenges. We systematically investigated the Galactic distribution of HCl and the [H$^{35}$Cl]/[H$^{37}$Cl] ratio in high-mass star-forming regions. As a probe of a region's nucleosynthesis history, this ratio may constrain predictions of Galactic chemical evolution models. We observed the ground-state $J=1$$-$0 lines of H$^{35}$Cl and H$^{37}$Cl toward 28 high-mass star-forming regions with SEPIA660 on APEX, more than doubling the number of known HCl detections and revealing with XCLASS models emission from both cores and outflows. H$^{35}$Cl was detected in all sources, H$^{37}$Cl in all but two, with spectral line profiles ranging from those with only emission to complex emission-absorption mixtures. We find column densities of the order of $10^{13}\,\mathrm{cm}^{-2}$ for H$^{35}$Cl and isotopic ratios between $1.6$ and $3.5$ in emission-only sources. The derived [H$^{35}$Cl]/[H$^{37}$Cl] aligns with Galactic chemical evolution models and shows no trend with Galactocentric radius. However, local variations may reflect recent nucleosynthesis. Overall, the results suggest that most Galactic chlorine was synthesized during epochs of lower average metallicity in the Galaxy. Notably, we detect H$^{35}$Cl emission arising from outflows - particularly explosive ones - hinting at its presence in a broader range of environments. The present single-dish observations cannot reveal the origin of HCl in outflows; necessitating interferometric follow-up observations.

Cold, dense streams of gas are predicted to penetrate deeply into massive halos (> 10^12 Msun) at cosmic noon (z=4-2), fueling galaxies to sustain high star formation rates. We investigate the prevalence of such cold streams in IllustrisTNG-50 over the range z=4-0, using a novel algorithm to automatically detect cold streams in simulated halos. We qualitatively and quantitatively characterize the geometric and physical properties of the detected streams over cosmic time. We find that cold streams are ubiquitous in massive halos at cosmic noon, occurring in more than 80 percent of such systems down to z=1, before becoming rare by z=0. At their peak prevalence (z=2-1), streams are often found in roughly co-planar, three-stream configurations. These streams generally exhibit a dense and cool core, surrounded by a diffuse and warmer envelope. However, we find that in IllustrisTNG-50, these streams typically disrupt in the outer halo and do not penetrate efficiently to the central galaxy, with the total mass inflow from streams peaking at z=2. Our results underscore the importance of cold streams in fueling galaxies at early times, but they highlight the need for higher-resolution simulations to fully capture their survival and impact at later epochs. Future cosmological zoom-in simulations, with better resolution in the CGM, will be essential to resolve turbulent mixing layers and feedback-inflow interactions that determine whether cold streams can reach the galactic disk.

We report on the results of the on-sky test and science demonstration conducted with the 2 mm receiver system, B4R, on the 50 m Large Millimeter Telescope (LMT), located at an altitude of 4600 m in Mexico. The B4R receiver was developed based on the dual-polarization sideband-separating mixer technology of the Atacama Large Millimeter/submillimeter Array, and is equipped with a fast Fourier transform digital spectrometer, XFFTS. The primary science objective is the spectroscopic redshift identification of high-redshift dusty star-forming galaxies, complementing the existing 3 mm Redshift Search Receiver by enabling the detection of multiple carbon monoxide lines. Additionally, the B4R receiver broadens the range of science cases possible with the LMT, including astrochemistry, as the 2 mm band encompasses unique molecular lines such as deuterated molecules and shock tracers. During on-site commissioning in 2018 and 2019, we successfully demonstrated on-the-fly mapping and position-switching observations toward the Orion Molecular Cloud 1 and bright high-redshift dusty star-forming galaxies, respectively. We confirmed that the installed B4R system largely met its basic performance specifications. Furthermore, we measured the LMT's aperture efficiencies across the entire B4R frequency range (130-160 GHz), finding them to be roughly consistent with expectations based on a surface accuracy of 100 $\mu$m and the receiver optics design. These results with the B4R will enable the most sensitive single-dish spectroscopic observations at 2 mm using the LMT.

Through detailed modeling of all three stars, we show that HIP-44302 is a false positive triple-star system. While the Transiting Exoplanet Survey Satellite initially designated the object as a planetary candidate, observing a 10-day transit and secondary eclipse in Sectors 8 and 35, we definitively exclude this scenario, finding instead that the transit comes from eclipsing stellar companions with $P = 9.599214$ days and $a = 0.1415$ AU. This binary orbits a single star at a wide separation of $\rho = 0.2946''$, determined through high-resolution AO and speckle imaging and corresponding to a $\sim$297 AU, $\sim$1886-year orbit at a distance of 1010 pc. Using transit data and photometry, we use EXOFASTv2 to fit the transit light curve, spectral energy distribution, and MIST evolutionary models of the three stars. We find that the isolated star and the larger binary star are massive A stars, with the single star having evolved off the main sequence, while the smaller companion is a G star. We also found an unusually low rotational velocity of 2.3 km/s from the single A star, observed from MINERVA and TRES RVs, implying a pole-on orientation. The triple-star architecture derived from multiple data sources made this target a complex system that required new capabilities within EXOFASTv2 to properly model. Our successful modeling demonstrates a new paradigm for false positive identification and classification that incorporates imaging, photometry, transits, and global modeling to definitively rule out false positives that may otherwise pollute candidate catalogs without extensive follow-up observations.

During a tidal disruption event (TDE) the stream debris inherits the magnetic field of the star. As the stream stretches, the magnetic field evolves and can eventually become dynamically important. We study this effect by means of magnetohydrodynamic simulations and a semi-analytic model of the disruption of a main-sequence star by a supermassive black hole. For stellar magnetic fields stronger than $\sim 10^4\,\rm{G}$, magnetic pressure becomes important in a significant fraction of the mass of the stream, leading to a fast increase in its thickness, an effect that may impact its subsequent evolution. We find that this dynamical effect is associated with a phase of transverse equilibrium between magnetic and tidal forces, which causes the stream width to increase with distance to the black hole as $H \propto R^{5/4}$. In the unbound tail, this fast expansion could enhance the radio emission produced by the interaction with the ambient medium, while in the returning stream, it may qualitatively affect the subsequent gas evolution, particularly the gas dynamics and radiative properties of shocks occurring after the stream's return to pericentre. By characterizing the magnetohydrodynamic properties of the stream from disruption to the first return to pericentre, this work provides physically motivated initial conditions for future studies of the later phases of TDEs, accounting for magnetic fields. This will ultimately shed light on the role of magnetic fields in enabling angular momentum transport in the ensuing accretion disk, thereby affecting observable signatures such as X-ray radiation and relativistic outflows.

We present the value-added catalogue JOLINES (J-PAS optical line intensities for nebular emission galaxies), which provides emission-line fluxes in galaxies at from the spectrophotometric catalogues of miniJPAS, J-NEP and the J-PAS early data release (EDR). This catalogue will be updated with future data releases, offering a growing resource for the study of emission-line galaxies. To obtain reliable emission-line fluxes from narrow-band photometry, we employed spectral energy distribution (SED) fitting using CIGALE, a robust tool that reconstructs the continuum emission and ensures accurate flux measurements. This method effectively mitigates uncertainties associated with direct continuum subtraction techniques, and systematics such as absorption components in the emission lines. We validate our approach using simulated observations of galaxy spectra with added noise, testing the method's performance across different equivalent width (EW) regimes and emission-line strengths. Additionally, we compare the recovered emission-line fluxes with spectroscopic measurements from the Sloan Digital Sky Survey (SDSS) and the Dark Energy Spectroscopic Instrument (DESI). Our results show a tight correlation between photometric and spectroscopic fluxes, particularly for bright emission lines, with a typical dispersion of $\sim$0.3 dex. Reliable fluxes are obtained for emission lines with EW $\gtrsim20\, \rm{\mathring{A}}$, in agreement with previous empirical studies. The current catalogue comprises approximately 13,900 sources with reliable flux measurements in the H$\alpha$+[NII] complex and 7,200 in [OIII]$\lambda 5007$, ensuring statistically robust samples for the brightest optical emission lines. This resource will be expanded in future J-PAS releases, facilitating large-scale studies of star formation, AGN activity, and galaxy evolution.

We present the first comprehensive study of astrometric microlensing by exotic astrophysical dark objects, focusing on two theoretically motivated models -- Q-ball and boson star. We demonstrate that these extended objects generate distinctive signatures that depart markedly from point-mass lenses like primordial black holes. The smoking-gun signature for these exotic objects is the emergence of caustics, which form when the lens radius is below a critical threshold. Crossing these caustics induces discontinuous jumps in the images-centroid trajectory, a distinctive feature of these extended dark objects. We show these patterns are sensitive to the internal mass profile, with boson stars generating larger, more prominent caustic structures than Q-balls -- enabling the models to be distinguished. Using the Gaia DR3 stellar catalogue, we forecast a high-yield discovery potential, up to $\sim 6000$ detectable astrometric microlensing events for a 10-year mission, peaking for $M \sim 1-10~M_\odot$ and $R \lesssim 10~\text{AU}$. In the absence of anomalous detections, Gaia can set powerful 90% confidence level constraints on the fractional abundance of these exotic objects, reaching $f_{\mathrm{DM}} \le 10^{-3}$ in the peak region which covers masses from $10^{-1}-10^{7}~M_{\odot}$ and radii $R<10^{6}~\text{AU}$. Crucially, these projected astrometric microlensing constraints are significantly stronger than existing photometric microlensing limits in the $1-10~M_\odot$ mass range. This work establishes astrometric microlensing with Gaia as a powerful, complementary, and near-future probe with the potential to discover exotic astrophysical dark objects.

We present a suite of zoom-in cosmological hydrodynamical simulations of dwarf galaxies using the LYRA galaxy formation model with an extremely high mass resolution of $4\, \mathrm{M_{\odot}}$, evolved to $z=0$. The suite contains 65 haloes selected from Local Group like environments, spanning $M_{\mathrm{200c}}=10^7$ to $5\times10^9\, \mathrm{M_{\odot}}$. The sample includes small ultra-faints with $M_\ast\sim100\, \mathrm{M_{\odot}}$ through to classical dwarfs with $M_\ast \sim 5\times10^6 \mathrm{M_{\odot}}$, as well as haloes that remain dark to the present day. We explore two prescriptions for the high-redshift ($z>7$) Lyman-Werner background (LWB), differing in intensity and redshift evolution. Star formation begins early ($z\gtrsim8$) in progenitors with $M_{\mathrm{200c}}\sim10^5$-$10^6 \mathrm{M_{\odot}}$, where molecular hydrogen enables warm moderate-density gas to efficiently cool. The LWB strongly influences the $z=0$ halo occupation fraction, shifting the dark-to-luminous transition from $M_{\mathrm{200c}}\sim10^7 \mathrm{M_{\odot}}$ (weaker LWB) to $M_{\mathrm{200c}}\sim10^8 \mathrm{M_{\odot}}$ (stronger LWB). Galaxies with $M_\ast\gtrsim10^5 \mathrm{M_{\odot}}$ are mostly insensitive to the LWB choice, whereas lower mass systems respond strongly, producing markedly different stellar mass-halo mass (SMHM) relations. The weaker LWB yields a very shallow SMHM slope with nearly constant scatter, while the stronger LWB introduces a pronounced break at $M_{\mathrm{200c}}\sim10^9 \mathrm{M_{\odot}}$, where haloes of similar mass host galaxies with $M_\ast\sim10^3$ to $10^5 \mathrm{M_{\odot}}$ or remain dark. Both models produce a minimum stellar mass floor at $M_\ast\sim10^3 \mathrm{M_{\odot}}$, originating from galaxies that undergo a single burst of star formation at high redshift before self-quenching from their first supernovae.

Spectroscopic parameters of methane from many different studies were gathered to improve the HITRAN database towards its 2024 version. After a validation process using high-resolution FTS and CRDS spectra, about 60,000 lines of the four most abundant isotopologues were replaced from the dyad to the triacontad regions. These changes amount to 56,000 transition wavenumbers, 16,000 line intensities, 30,000 pressure-broadening half-widths, and 3500 assignments. 40,000 new lines were added, extending the database from 12,000 cm$^{-1}$ up to 14,000 cm$^{-1}$, and covering some gaps. A greater focus was brought on the pentad, octad, and tetradecad regions, targeted by several remote instruments. In these regions, comparisons of spectral fits from multiple line lists were performed, taking only the parameters that provide best fit for each line. In the $\nu _3$ band, in addition to replacing the previous values, gathered speed-independent pressure broadenings of $^{12}$CH$_4$ were used to fit Pade-approximant functions. These functions then replaced any outdated experimental data in $\nu _3$, missing data in the new lines, as well as the values that were determined to be outside their physical boundaries. The CH$_3$D broadenings were replaced in the same manner, for missing and low or high values, using a semi-empirical formula instead.

We present the results of mapping and single-point spectral scans toward Orion-KL/OMC-1 performed as science demonstrations of a 2 mm SIS receiver, the Band 4 Receiver (B4R), installed on the 50 m Large Millimeter Telescope (LMT). To prove the capabilities of mapping and spectral scans with the B4R on the LMT, commissioning observations were conducted employing the on-the-fly mapping technique toward Orion-KL/OMC-1, which covers a map size of 5$'\times$5$'$. These mapping observations were performed with two frequency settings providing 10 GHz in total (131.4-133.9 GHz and 145.1-147.6 GHz; 136.2-138.7 GHz and 149.9-152.4 GHz) with a frequency resolution of 76.293 kHz. We conducted spectral line identification analysis for the hot core and compact ridge regions in the Orion-KL with a beam size of 11-12$''$. We detected nearly 400 emission lines and identified two recombination lines and 29 molecular species, including isotopologues, deuterated molecules, and vibrational excited states, despite the short integration time. These results are consistent with those of previous studies. The 29 molecular species include nitrogen (N)-bearing complex organic molecules (COMs) and oxygen (O)-bearing COMs. To demonstrate the capability of the B4R in astrochemistry, we conducted detailed analyses of column densities, rotational temperatures, and relative abundances with respect to H$_2$ on two representative COMs, N-bearing C$_2$H$_5$CN and O-bearing CH$_3$OCHO in the central 40$''\times$40$''$ area of the map. The wide bandwidth of 10 GHz enabled the use of 8 and 34 emission lines, respectively. The spatial differences in the physical and chemical properties between these molecules were derived at a spatial resolution of $\sim$12$''$. The B4R on the LMT was successfully demonstrated to be powerful for mapping and spectral scans and to have high potential for the study of interstellar chemistry.

The recent detections of radio emission from the nearby exoplanet host, YZ Ceti, suggest that the star is possibly interacting with its rocky innermost planet. These radio emissions are characterized by strong circular polarization, and appear to repeat within consistent orbital phase windows dictated by the orbital position of YZ Ceti b. If confirmed, this interaction would provide a first means to concretely assess the magnetic field of a close-in rocky exoplanet. This kind of magnetic star-planet interaction (SPI) should depend on both the exoplanetary orbit, and the geometry of the stellar magnetic field. In this article, we report measurements of the large-scale magnetic field topology of the star YZ Ceti for the first time, and interpret the cumulative radio data sets in that context to evaluate the plausibility of magnetic SPIs. We find evidence both against and in support of the SPI hypothesis, but crucially that the measured magnetic field does not rule out SPI scenarios. However, clear evaluation of these possibilities requires more accurate assessments of the magnetic field evolution across time. We additionally suggest that YZ Ceti may be exhibiting planet-induced flaring potentially triggered by exoplanet crossings of the Alfvén surface as the planet orbit approaches the stellar magnetic equator, and YZ Ceti b experiences dramatic shifts in the ambient field, its polarity, and connectivity to the host star.

We present a detection of the intrinsic galaxy alignments in the CAMELS suite of hydrodynamic simulations. We find that the alignment amplitude depends significantly on cosmological and supernova feedback parameters - specifically $\Omega_m$, $\sigma_8$, $A_{\text{SN1}}$, $A_{\text{SN2}}$- while no dependence on AGN feedback is observed (due to the limited simulation volume $(25\,h^{-1}\,\text{Mpc})^3$). The dependence on $\sigma_8$ vanishes when projected correlation functions $w_{m+}$ are normalized by matter density correlations $w_{mm}$, consistent with predictions from linear alignment models. We find alignment amplitudes in quiescent galaxies to exceed those in star-forming galaxies by an order of magnitude. Moreover, examining orientation-only correlation functions from ellipticity-normalized galaxies $\tilde w_{m+}$, we confirm that alignment signals retain sensitivity to supernova feedback across full, star forming, quiescent, and ellipticity-normalized samples. Finally, we find evidence that supernova feedback impacts alignment signals differently in star-forming versus quiescent populations, suggesting that distinct alignment mechanisms operate across galaxy types. Our results offer key insights for understanding galaxy formation and alignment models for future weak gravitational lensing analyses.

We present the gravitational wave predictions from two-dimensional core collapse supernova (CCSN) simulations initiated from two nearly identical progenitors that have significantly different internal structures due to their late-stage stellar evolution. At the time of collapse, the 15.78 $M_{\odot}$ and 15.79 $M_{\odot}$ progenitors have compactness parameters $\xi_{2.5}$ of 0.136 and 0.206, respectively. We connect several features of the gravitational wave signal from each model to its previously explored explosion dynamics. In particular, the greater accretion onto the PNS of the more compact model is evident in broad-band frequency features with larger amplitude gravitational wave strains and greater gravitational wave energy release when compared to the less compact model. Additionally, the faster contraction rate of the more compact model is reflected in the $\sim$26% greater slope of the $g$-/$f$-mode feature (gfF) evolution of the gravitational wave signal. This work shows that in principle gravitational wave detection may provide information about interior stellar structure.

Self-consistently modeling baryonic effects in survey-scale cosmological simulations has become increasingly important as the diversity, precision, and statistical reach of modern observations continue to improve. The advent of exascale computing now enables a new generation of simulations that couple these physical processes across full-sky volumes with excellent statistical sampling of large-scale structure tracers such as galaxies, groups, and clusters. To support these efforts, we extend the CRK-HACC framework, a GPU-accelerated cosmological hydrodynamics code, with a suite of astrophysical subgrid models that simulate radiative cooling, star formation, stellar evolution, and AGN feedback within a numerically robust formulation optimized for scalability on modern exascale architectures. The models were selected and calibrated to reproduce observed galaxy stellar mass functions over the redshift range $0 < z < 2$ and cluster populations probed by cosmological surveys, capturing the large-scale baryonic evolution relevant for multi-wavelength, cross-correlated analyses. We describe the implementation and calibration of these models and demonstrate their consistency with observed galaxy population statistics and modern hydrodynamic simulations, establishing the baseline for exascale efforts that extend this framework to survey-scale volumes.

Results of a case study of a sample of low-redshift galaxies are presented, to determine dust temperatures and emissivity indices through a less time-consuming method, and to connect both global and integrated galaxy properties with those of dust, ISM and star-formation. Dust temperatures ($T_{d}$) are determined based on the corresponding galaxy dust masses, independently calculated in our previous work, through a self-consistent method, without the need to actually perform a complete spectral energy distribution (SED) fit of the cold dust emission fluxes. The range and average dust temperatures are found to be consistent within errors with values from other studies. Simultaneously, the dust emissivity indices ($\beta_{d}$) are determined, and their evolution with temperature quantified, with the $T_{d}$ anti-correlation still being present. It is investigated whether $\beta_{d}$ can be predicted from other relation or if it scales with other integrated dust / ISM or galaxy property, which could be used as a proxy. In this respect, new and established relations between $T_{d}$, $\beta_{d}$, the dust surface density and global / integrated galaxy and star-formation related quantities are presented and analysed. We find that SFR, sSFR or $\Sigma_{SFR}$ are inconclusive traces of the dust temperature. We also find that the extent of dust emission distribution is slightly lower on average, but comparable with the optical stellar continuum emission one. The results and conclusions can be relevant for larger scales studies of low to mid-redshift galaxies from the latest surveys.

Pulsar Timing Arrays (PTAs) are approaching the sensitivity required for a $5\sigma$ detection of the nanohertz stochastic gravitational-wave background (GWB). This makes it crucial to deeply understand the behaviour of our analysis pipelines. A counterintuitive feature of the European Pulsar Timing Array (EPTA) second data release is that restricting the dataset to the last 10.3 years (DR2new) increases the inferred GWB significance from $\leq2\sigma$ for the full 25-year dataset (DR2full) to $\geq3.5\sigma$. We investigate whether this behaviour indicates an anomaly or is a possible outcome of the pipeline. Using realistic, DR2-like simulations with varying timespans, we find that the first 10 years contribute little to the GWB evidence due to their limited frequency coverage. This produces substantial overlap between the HD S/N distributions of DR2full and DR2new. Random noise fluctuations therefore yield a higher GWB evidence in DR2new than in DR2full in $15\%$ of cases. Furthermore, $5\%$ of simulations match the HD S/N of the real data, indicating that the observed behaviour is consistent with being a $\sim2\sigma$ outcome due to noise fluctuations. Regardless of significance, DR2new simulations introduce biases in the GWB parameter estimation due to spectral leakage effects that are ignored in standard analyses and which flatten the inferred spectrum. Including leakage removes these biases, demonstrating the reliability of DR2new when the signal is properly modelled. Furthermore, we demonstrate that combining EPTA DR2full with long-baseline data from NANOGrav and PPTA, as well as low-frequency data from LOFAR and NenuFAR, significantly enhances GWB evidence and parameter accuracy. Finally, we examine the impact of the observation timespan and find that short-baseline datasets introduce strong amplitude biases and are ineffective at constraining the GWB.

Context. Neptune-sized exoplanets or exo-Neptunes are fundamental in the description of exoplanet diversity. Their evolution is sculpted by atmospheric escape, often traced by absorption in the H i Lyman-{\alpha} line at 1,216 Å and the He i triplet line at 1.08 {\mu}m. On warm exo-Neptunes HAT-P-11 b, GJ 3470 b and GJ 436 b, H i Lyman-{\alpha} absorption causes extreme in-transit obscuration of their host stars. This suggests that He i triplet line absorption will also be strong, yet it has only been identified on two of these planets. Aims. We explore previously unaccounted for processes that might attenuate the He i triplet line on warm exo-Neptunes. In particular, we assess the role of vibrationally excited H2 to remove the He+ ion that acts as precursor of the absorbing He(2$^3$S ). Methods. We formed thermal rate coefficients for this chemical process, leveraging the available theoretical and experimental data. The process becomes notably fast at the temperatures expected in the atmospheric layers probed by the He i triplet line. Results. Our simulations show that the proposed process severely mutes the line on GJ 3470 b and causes the nondetection on GJ 436 b. The overall efficiency of this mechanism is connected to where in the atmosphere the H2-to-H transition occurs and, ultimately, to the amount of high-energy radiation received by the planet. The process will be more significant on small exoplanets than on hotter or more massive ones, as for the latter the H2-to-H transition generally occurs deeper in the atmosphere. Conclusions. Weak He i triplet line absorption need not imply the lack of a primordial, H2-He-dominated atmosphere, an idea to bear in mind when interpreting the observations of other small exoplanets.

Long secondary periods (LSPs) occur in about one-third of evolved stars, yet their origin remains unclear. The leading explanations are oscillatory convective modes and a binary companion embedded in dust. We investigate the LSP of the red giant RT Pav using multi-wavelength VLTI interferometry (PIONIER, GRAVITY, MATISSE; 1.5-5.0 microns), obtained near the phase where a companion would appear most separated. These data, combined with photometry and Gaia DR3 astrometry, constrain possible companion masses, orbits, and photometric effects. We model the interferometric observables using uniform-disk, limb-darkened, ellipse, binary, and oscillatory convective dipole representations, supported by Monte Carlo simulations. Gaia limits any companion to a mass whose Roche-lobe volume is too small to hold the obscuring or scattering material required to reproduce the observed LSP modulation. While binary fits can yield low chi-squared values, the inferred positions are inconsistent across wavelength, closure phases do not increase with wavelength as dusty companions predict, and significant detections occur in only two of four bands. Theoretical estimates show that a roughly 1 percent flux companion at LSP-like separations should be consistently detectable for typical O-rich AGB dust, but is not consistently observed. In contrast, an oscillatory convective dipole with a temperature contrast of about 200 K reproduces the H-band morphology and visible-light amplitude without violating Gaia or photometric constraints, and binary-like residuals vanish when dipole models are fitted. Our results therefore favor oscillatory convective modes over a binary origin for the LSP in RT Pav. Time-resolved spectro-interferometry across the LSP cycle is a natural next step.

We present an explicit numerical implementation of the Friedmann equations to model the expansion of the Universe in spatially flat, homogeneous and isotropic Friedmann-Lemaitre-Robertson-Walker (FLRW) cosmologies. Using cosmological parameters from the Planck 2018 results for the concordance LCDM model, we compute the evolution of the scale factor a(t) by integrating the Friedmann acceleration equation together with the continuity equation for a perfect fluid with barotropic equation of state p = w*rho. The model includes radiation, non-relativistic matter, and a dark-energy component with constant equation-of-state parameter w. An explicit Euler scheme implemented in Python is used to evolve a(t) into the past and the future, allowing exploration of the qualitative behavior of the expansion for different values of w, including the LCDM case (w = -1), phantom energy (w < -1), and values associated with domain walls and cosmic strings. The simulations qualitatively reproduce the standard radiation-, matter-, and dark-energy-dominated expansion regimes. The code is simple and modular, and is intended as a computational and pedagogical tool for undergraduate and graduate cosmology courses.

Understanding the astrophysical origins of binary black holes requires accurate and flexible modeling of multi-dimensional population properties. In this paper, using a data-driven framework based on binned Gaussian processes, we characterize the joint distribution of BBH primary masses, mass ratios, and effective inspiral spins. We identify three distinct subpopulations in the GWTC-4 sample of observations and investigate their astrophysical origins. We find that only one of the three subpopulations exhibits the $35M_{\odot}$ peak, which is characterized by a strong preference for equal mass systems and isotropic spin orientations. Our inferred distributions are consistent with a predominantly dynamical origin of this feature. By comparing with theoretical simulations, we further show that the subpopulation that exhibits the $35M_{\sun}$ peak can exclusively comprise dynamically assembled systems in globular clusters, specifically if black hole birth spins are in the range~$(0.1-0.2)$, whereas the other two subpopulations require substantial contributions from alternative formation channels. We constrain the \textit{lower bound} on the merger rate of BBHs in globular clusters to be $0.69^{+0.23}_{-0.33} \rm{Gpc}^{-3}\rm{yr}^{-1}$, which is consistent with theoretical predictions. We conclude that dynamical formation in globular clusters remains a strong candidate for the origin of this excess near $30-40M_{\odot}$ and that more data and targeted parametric models are necessary to rigorously establish this interpretation.

Nonthermal emission observed in galaxy clusters provides a direct probe into the plasma physics of the intra-cluster medium (ICM) under extreme conditions. We report the first detailed analysis of the giant radio halo in the merging galaxy cluster Abell 2163, using upgraded Giant Metrewave Radio Telescope (uGMRT) and Very Large Array (VLA) observations. Combining radio data (300-1400 MHz) with archival X-ray data offers a unique opportunity to study the complex ICM physics of the cluster. The sensitive uGMRT observations map the halo emission for the first time out to an extent of ~3.3 Mpc, up to $r_{500}$, and also effectively recover other diffuse sources. The radio surface brightness profile is well fitted with an exponential function up to r$_{500}$, with an evolution of e-folding radius over frequencies (larger at low frequencies). The spatially resolved spectral index map reveals fluctuations and outward radial steepening of the average spectral index. Radio and X-ray surface brightness are well correlated, with a correlation slope of $\sim$0.70 for the halo, and $\sim$0.40 for the ridge. The correlation slope varies from cluster centre to outskirts, suggesting the magnetic field and thermal gas density scaling relation (B $\propto n_{e}^{0.5}$) should be reassessed, provided that the re-acceleration efficiency is constant. We propose that diffuse lobes at the periphery could serve as a reservoir for seed electrons, behind the radio halo emission, with an estimated acceleration efficiency reaching $\sim$0.1% in the external regions. Additionally, a major E-W merger is suggested, leading to turbulence in the ICM and generating the halo.

A newly born millisecond magnetar has been proposed as one possible central engine of some long gamma-ray bursts (LGRBs) with X-ray plateau. In this work, we used a universal correlation between initial spin period ($P_0$) and surface magnetic field ($B_p$) of newborn magnetar based on an LGRB sample in \cite{Lan2025} to explore the propeller properties of accreting magnetar with $R/I$ evolutionary effects. We found that $B_p-P_0$ relation is approximately consistent with $B_p\propto P_{\rm eq}^{7/6}$. Here, $P_{\rm eq}$ is equilibrium spin period in magnetic propeller model. The $B_p-P_0$ relation indicates that $P_0$ may not be true initial spin period of newborn magnetar, but had reached an equilibrium spin period via fallback accretion in propeller model. The magnetar accretion rate in our LGRBs is in range of $\dot{M}\sim10^{-5}-10^{-2} M_{\odot} \rm s^{-1}$ by incorporating $R/I$ evolutionary effects, and using the transition relation between gravitational mass $M_g$ and baryonic mass $M_b$ in different equation of states. Such accretion rates ensure that the accreting magnetars in our sample survive until reaching the equilibrium spin period, and the accretion rate is one order of magnitude lower compared to the statistical results in \cite{Stratta2018} and \cite{Linweili2020}, which used constant $R/I/M_g$ scenario. We suggested that adopting a constant $R/I/M_g$ scenario for modeling propeller regime in accreting magnetar results in a higher mass accretion rate, which may impair our understanding of the physical nature and its surroundings of accreting magnetar, and low-metallicity progenitors can provide enough material to satisfy the accretion requirements of newborn accreting magnetar in LGRBs.

This paper presents the design and testing of a millimeter-wave frequency comb generator developed for the Black Hole Explorer (BHEX) mission, a space Very-Long-Baseline Interferometry (VLBI) mission concept. The heart of BHEX is a dual-band receiver, centered at 90 and 270 GHz. This novel comb generator is based on a microwave phase modulator producing phase-coherent comb signals with multi-octave bandwidth, which will be used to track instrumental delays when injected into the receiver system. The comb generator was tested with astronomical receivers, which confirms its expected operation.

We present a Gaussianity test of the cosmic microwave background (CMB) polarization by analyzing the statistics of unpolarized points in the sky, classified into three distinct types: saddles, comets, and beaks. This classification of singular points where both Stokes parameters $Q$ and $U$ vanish stems from the fact that linear polarization is described by a second-rank tensor. By varying the number of spherical harmonics included in the polarization maps, one can probe the statistics of these singularities across a range of angular scales. Applying this method to Planck data we find clear evidence of non-Gaussianity in both $E$ and $B$ modes of polarization. This approach may be especially useful for processing data from current and future experiments such as the Simons Observatory (SO). In particular, it can help to assess the Gaussianity of a potentially detected B mode signal, thereby determining whether it arises from primordial tensor perturbations -- as predicted by inflation -- or from alternative sources such as polarized foregrounds (e.g., thermal dust), E-to-B mode leakage, systematics, photon noise or gravitational lensing. We have made publicly available software that finds unpolarized points of all three types on any polarization map in Hierarchical Equal Area isoLatitude Pixelation (HEALPix) format with full or incomplete sky coverage to enable testing of the observed signal for Gaussianity.

Primordial non-Gaussianities (PNGs), characterized by $f_{\rm NL}^{\rm loc}$, provide a powerful window into the physics of inflation. Cross-correlating high-redshift tracer samples with the CMB lensing potential offers a particularly robust probe of PNGs, mitigating imaging systematics that typically affect large-scale measurements from tracer auto-spectra. In this context, UNIONS enables the selection of $u$-dropout high-redshift Lyman-Break Galaxies (LBGs). We perform a MCMC-based forecast to estimate the uncertainties on $f_{\rm NL}^{\rm loc}$ and on a galaxy bias parameter, which captures our uncertainty in the tracer bias. From the angular cross-power spectrum between LBGs and Planck CMB lensing, we forecast $\sigma(f_{\rm NL}^{\rm loc})=34$ for an idealized photometric sample of $r<24.3$ LBGs selected with a Random Forest classification algorithm from UNIONS-like $ugriz$ imaging, with a resulting surface density of $1,100$ deg$^{-2}$. This precision can be improved to $\sigma(f_{\rm NL}^{\rm loc})=20$ after spectroscopic follow-up with DESI, during its next phase starting in 2029, DESI-II. We test a more realistic $u$-dropout LBG selection using early UNIONS data, which yields a denser sample of $r<24.2$ objects at $1,400$ deg$^{-2}$. From this sample, covering a larger footprint and expected to have a higher large-scale galaxy bias, we forecast $\sigma(f_{\rm NL}^{\rm loc})=20$, with similar precision achievable after DESI spectroscopic follow-up. In addition, we perform preliminary validation of the redshift distribution using the clustering-redshift method with DESI DR1 data, confirming the calibration from deep, small-area photometric fields. However, accounting for uncertainties in the clustering-redshift distribution significantly degrades the $f_{\rm NL}^{\rm loc}$ constraining power.

In this paper, we construct a detailed circular velocity curve of the Milky Way out to 20 kpc based on the radial component of the Jeans equation in cylindrical coordinates, assuming an axisymmetric gravitational potential, and show its dependence on azimuth. We use only Gaia DR3 data and aim to minimize the use of model data and various assumptions. To build the rotation curves, we used a sample of 4,547,980 RGB stars with measured spatial velocities, covering the Galactic plane in the range of Galactocentric cylindrical coordinates $150^\circ < \theta < 210^\circ$ and 0 < R < 20 kpc. We exclude systematics in the data that may arise from neglecting higher-order moments of the velocity distribution and their dispersions, as well as due to random measurement errors in Gaia. At the distance of the Sun, the circular velocity $V_{\rm c}(R_0)$ turned out to be ($229.63\pm0.30$) km s$^{-1}$, which is in good agreement with many previous estimates. The average slope of the circular velocity is $(-2.29\pm0.05)$ km s$^{-1}$ kpc$^{-1}$ obtained in the range of $R$ from 6 to 20 kpc and $\theta$ from 150 to 210 degrees. The determined circular velocity curve has some peculiarities in behavior near $R\sim$13 and 18 kpc, but in general it does not contradict the results of other authors up to distances where our statistics are reliable.

In high precision pulsar timing, the accurate recovery of intrinsic pulsar profiles and their associated scattering parameters is of paramount importance. In this paper, we present a comprehensive study focused on the retrieval of intrinsic pulsar profiles through the utilization of a CLEAN-based algorithm as described in Bhat et al. (2003). The primary objective of this study is to elucidate the capabilities of our pipeline in the context of recovering the intrinsic profiles and associated parameters, such as dispersion measure, frequency scaling index, scattering time, pulse broadening function, and time of arrival residuals. We use simulated profiles to rigorously test and validate the efficiency of our recovery pipeline. These simulated profiles encompass single and multi-component Gaussians, designed to emulate the diverse nature of pulsar profiles. By comparing the recovered profiles and parameters to their injected values, as derived from simulations, we provide a robust evaluation of the pipeline's performance along with its drawbacks and limitations.

High-precision measurements of the Cosmic Microwave Background (CMB) will soon allow for the unprecedented detection of small-scale secondary anisotropies, such as the kinetic Sunyaev-Zel'dovich (kSZ) effect. Linking the kSZ power spectrum to the properties of ionising sources would provide an opportunity to use such observations to access astrophysical and cosmological information from the Epoch of Reionisation, including the morphology of ionised regions, while simultaneously improving CMB analyses. The aim of this work is to assess this potential of the kSZ power spectrum to measure reionisation-era galaxy properties. We repurpose the publicly available LoReLi II simulations, which track the evolution of neutral hydrogen during reionisation, to generate a training set of patchy kSZ angular power spectra. We then train an emulator using neural network regression in order to allow for efficient Bayesian inference, and conduct forecasts assuming mock observations from current and future CMB experiments. We find that measurements of the kSZ power spectrum from such surveys can provide meaningful constraints on several of the astrophysical model parameters of the LoReLi II suite, including the ionising escape fraction for which we expect a 14% relative error, on average. They also provide an independent measurement of the CMB optical depth, marginalised over the astrophysics and with error bars competitive with the cosmic variance limit from large scale surveys. The kSZ power spectrum offers a promising avenue for probing the properties of reionisation-era galaxies and providing an independent measurement of the CMB optical depth with upcoming CMB experiments. Since the error budget of our mock observations is dominated by emulator reconstruction errors, we expect our results could be further improved with a more extended simulation training set.

The mechanical feedback from the central AGNs can be crucial for balancing the radiative cooling of the intracluster medium at the cluster centre. We aim to understand the relationship between the power of AGN feedback and the cooling of gas in the centres of galaxy clusters by correlating the radio properties of the brightest cluster galaxies (BCGs) with the X-ray properties of their host clusters. We used catalogues from the first SRG/eROSITA All-Sky Survey (eRASS1) along with ASKAP radio data. In total, we identified 134 radio sources associated with BCGs of the 151 eRASS1 clusters located in the PS1, PS2, and SWAG-X ASKAP fields. Non-detections were treated as upper limits. We correlated BCG radio luminosity, largest linear size (LLS), and BCG offset with the integrated X-ray luminosity of their host clusters. To characterise cool cores (CCs) and non-cool cores (NCCs), we used the concentration parameter $c_{R_{500}}$ and combined it with the BCG offset to assess cluster dynamical state. We analysed the correlation between radio mechanical power and X-ray luminosity within the CC subsample. We observe a potential positive trend between LLS and BCG offset, suggesting an environmental effect on radio-source morphology. We find a weak trend where more luminous central radio galaxies are found in clusters with higher X-ray luminosity. Within the CC subsample, there is a positive but highly scattered relationship between the mechanical luminosity of AGN jets and the X-ray cooling luminosity. This finding is supported by bootstrap resampling and flux-flux analyses. The correlation indicates that AGN feedback is ineffective in high-luminosity (high-mass) clusters. At a cooling luminosity of $L_{\mathrm{X},~r<R_\mathrm{cool}}\approx 5.50\times10^{43}$ erg/s, on average, AGN feedback appears to contribute only about 13%-22% of the energy needed to offset the radiative losses in the ICM.

A 50-mm balloon-borne white-light coronagraph (BBWLC) to observe whitelight solar corona over the altitude range from 1.08 to 1.50 solar radii has recently been indigenously developed by Yunnan Observatories in collaboration with Shangdong University (in Weihai) and Changchun Institute of Optics, Fine Mechanics and Physics, which will significantly improve the ability of China to detect and measure inner corona. On 2022 October 4, its first scientific flight took place at the Dachaidan area in Qinghai province of China. We describe briefly the BBWLC mission including its optical design, mechanical structure, pointing system, the first flight and results associated with the data processing approach. Preliminary analysis of the data shows that BBWLC imaged the Kcorona with three streamer structures on the west limb of the Sun. To further confirm the coronal signals obtained by BBWLC, comparisonswere made with observations of the Kcoronagraph of the High Altitude Observatory and the Atmospheric ImagingAssembly on board the Solar Dynamics Observatory. We conclude that BBWLC eventually observed the white-light corona in its first scientific flight.

The regions in which stellar winds interact with the interstellar medium, also known as astrospheres, can be observed in detail through the thermal emission of the interstellar dust particles, resided in plasma. Interstellar dust is also directly observed in the vicinity of the Sun with dust detectors onboard spacecraft, and it is known to be affected by the interplanetary magnetic field. The main goal of this work is to show how the change in the interplanetary magnetic field with the solar cycle affects the infrared picture of the heliosphere. To compose a synthetic intensity map of the interstellar dust thermal emission, we used the Monte Carlo method to calculate the distribution of the dust particles inside the heliosphere. We considered the effects of the heliosphere boundaries and the non-stationary current sheet. The change in the Parker magnetic field caused by the solar activity cycle leads distinguishable features in the mid-infrared emission maps of the heliosphere. The distribution of the interstellar dust in the vicinity of the Sun we calculated suggests that small particles linger outside of the heliosphere, and medium-size particles are mostly affected by the changing interplanetary magnetic field, which leads to number density waves in the tail region of the heliosphere. Finally, large particles form a bulge behind the Sun.

We investigated the star formation history and stellar populations of a sample of 205 Type I quasar host galaxies (0.1$<$z$<$0.35) and compared with normal (non-active) galaxies of the same mass and redshift within the volume of the Galaxy and Mass Assembly (GAMA) redshift survey. We find that quasar host galaxies tend to be star-forming galaxies ($\sim$ 80%) lying on the star-forming MS; the fraction of quasar host galaxies that are quiescent ($\sim$ 20%) is lower than the fraction of quiescent galaxies in the comparison sample of normal galaxies (54%). We find that the mean star formation rate of quasar host galaxies has increased over the past 100 Myr by a factor of 2--3, but these galaxies were star-forming at all times previously. Our data are more consistent with quasar activity originating together with an increase in the star formation rate of otherwise normal galaxies, similar to episodic star formation in normal spirals. We argue that this indicates that secular processes and minor mergers may be the favored triggers of nuclear activity in the local Universe.

We introduce \textsc{Odisseo} (Optimized Differentiable Integrator for Stellar Systems Evolution of Orbits), a differentiable N-body code designed to constrain the gravitational potential of the Milky Way (MW) through dynamical modeling of accreted structures such as stellar streams. \textsc{Odisseo} is implemented in JAX, enabling just-in-time compilation, automatic differentiation, and hardware acceleration on GPUs and TPUs. The code features efficient, fully vectorized force calculations and exhibits near-linear scaling when distributing a single simulation across multiple GPUs, making it suitable for large scale optimization tasks. As a demonstration, we present a case study using a mock GD-1 stellar stream simulation, where we optimize four physical parameters via gradient descent: the accretion time and progenitor mass, as well as the masses of the host Navarro-Frenk-White (NFW) halo and Miyamoto-Nagai (MN) disk. \textsc{Odisseo} accurately recovers stream morphology and underlying parameters in a differentiable and scalable framework, providing a powerful tool for dynamical studies of the Milky Way and its accreted substructures.

We investigate the clustering properties of dynamical dark energy using the latest cosmological observations. We describe the dark energy perturbation within two complementary frameworks, namely the Parameterized Post-Friedmann (PPF) approach and the Effective Field Theory (EFT) of dark energy. Using DESI DR2 baryon acoustic oscillations together with Planck 2018 CMB data and the Union3 supernova sample, we constrain the effective sound speed of dark energy in both the $w$CDM and $w_0w_a$CDM backgrounds. Within the PPF description, the sound speed remains unconstrained for $w$CDM, while for the $w_0w_a$CDM case we obtain $\log_{10} c_s^2 = -3.00^{+2.9}_{-0.99}$. Additionally, in the EFT framework, both models favor a small sound speed, with a mean value $c_s^2 \simeq 0.3$--$0.4$ but with significant uncertainties. For dynamical dark energy, the reconstructed equation of state clearly exhibits a quintom-B behavior, and its deviation from $\Lambda$CDM reaches $3.42\sigma$, rising to $3.63\sigma$ when PPF perturbations are included and reducing to $3.19\sigma$ in the EFT case. Finally, model comparison using information criteria shows that the $w_0w_a$CDM model with a smooth, non-clustering dark energy component ($c_s^2 = 1$) is preferred by AIC, whereas BIC favors $\Lambda$CDM. In summary, current data indicate a mild preference for dynamical dark energy but no evidence for significant clustering, which implies the need for future high-precision observations to probe the perturbative behavior more definitively.

Classical Cepheids (CCs) have long been considered excellent tracers of the chemical evolution of the Milky Way's young disk. We present a homogeneous, NLTE spectroscopic analysis of 401 Galactic CCs, based on 1,351 high-resolution optical spectra, spanning Galactocentric distances from 4.6 to 29.3 kpc. Using PySME with MARCS atmospheres and state-of-the-art grids of NLTE departure coefficients, we derive atmospheric parameters and abundances for key species tracing multiple nucleosynthetic channels. Our sample-the largest CC NLTE dataset to date-achieves high internal precision and enables robust modeling of present-day thin-disk abundance patterns and radial gradients. We estimate abundance gradients using three analytic prescriptions (linear, logarithmic, bilinear with a break) within a Bayesian, outlier-robust framework, and we also apply Gaussian Process Regression to capture non-parametric variations. We find that NLTE atmospheric parameters differ systematically from LTE determinations. Moreover, iron and most elemental abundance profiles are better described by non-linear behavior rather than by single-slope linear models: logarithmic fits generally outperform simple linear models, while bilinear fits yield inconsistent break radii across elements. Gaussian Process models reveal a consistent outer-disk flattening of [X/H] for nearly all studied elements. The [X/Fe] ratios are largely flat with Galactocentric radius, indicating coherent chemical scaling with iron across the thin disk, with modest positive offsets for Na and Al and mild declines for Mn and Cu. Comparison with recent literature shows overall agreement but highlights NLTE-driven differences, especially in outer-disk abundances. These results provide tighter empirical constraints for chemo-dynamical models of the Milky Way and set the stage for future NLTE mapping with upcoming large spectroscopic surveys.

Recent baryon acoustic oscillation (BAO) measurements released by DESI, when combined with cosmic microwave background (CMB) data and type Ia supernova (SN) data, suggest a significant preference for dynamical dark energy (DDE) that exhibits the phantom-like behavior in the past and has transitioned into quintessence-like behavior today. In this work, we conduct a comprehensive analysis of six representative DDE parametrization models by utilizing the latest and most precise CMB data jointly from ACT, SPT, and Planck, in conjunction with BAO data from DESI DR2 and SN data from DESY5, PantheonPlus, and Union3. Our overall analysis indicates that the preference for DDE in the Quintom-B regime remains robust, regardless of the DDE parameterization model and the data combination employed. The trend of this preference is significantly strengthened with the support of DESY5 SN data. Specifically, when using the CMB+DESI+DESY5 data, for the Barboza-Alcaniz (BA) model, we obtain $w_0 = -0.785 \pm 0.047$ and $w_a = -0.43^{+0.10}_{-0.09}$, which significantly deviate from the $\Lambda$CDM values and provide evidence for DDE at the $4.2\sigma$ level. By the reconstruction of the dark energy equation of state $w(z)$, normalized dark energy density $f_{\mathrm{DE}}(z)$, and the deceleration parameter $q(z)$, we also observe clear departures from $\Lambda$CDM, further reinforcing the case for DDE. Furthermore, the Bayesian evidence analysis indicates that the Chevallier-Polarski-Linder, BA and Exponential models are moderately favored relative to $\Lambda$CDM based on the CMB+DESI+DESY5 data.

After six years of studies following the discovery of GSN069, a link is starting to appear between the elusive Quasi-Periodic Eruptions (QPEs) and other types of nuclear transients, among which are Tidal Disruption Events (TDEs). As such, observing strategies are adapting, with a current trend focusing on late-time X-ray follow-ups of (optical) TDEs. While these campaigns are so far proving quite successful, the inherent confirmation bias they introduce in our sample could lead the community to hasty, and perhaps erroneous, conclusions. It is thus important to still pursue the search for nuclear transients in other, more agnostic directions. In this work, we focus on the observational aspects of our field, and lay out two different methods that can be deployed in order to reveal new QPE sources. These complementary methods enable the detection of long-term ($\sim$years) and short term ($\sim$minutes) transient events, that would have otherwise been missed by the standard detection pipelines. Both of these methods can be used either for data mining in the 25 years worth of XMM-Newton archive, or to trigger real-time follow-ups upon a more recent discovery.

High-resolution, near-infrared observations have revealed prominent, two-armed spirals in a multitude of systems, such as MWC~758, SAO~206462, and V1247~Ori. Alongside the classical theory of disk-companion interaction, shadow-based driving has come into vogue as a potential explanation for such large-scale substructures. How might these two mechanisms be distinguished from one another in observations? To investigate this question, we ran a pair of hydrodynamical simulations with \texttt{PLUTO}. One, with full radiation hydrodynamics and gas-grain collision, was designed to develop shadow-driven spirals at the outer gap edge of a sub-thermal, Saturn-mass planet. The other, with parametrized $\beta$-cooling, was set up to capture the more standard view of spiral wave excitation by a super-thermal, multi-Jupiter-mass, exterior planetary companion. Post-processing of these simulations with the Monte Carlo radiative transfer (MCRT) code \texttt{RADMC3D} revealed that strong vertical velocities in the shadow-driven case create a prominent two-armed feature in the moment-1 CO maps, particularly when the disk is viewed face-on in optically thicker isotopologues; such a feature is not seen in the standard planet-driven case. Conversely, the presence or absence of such signatures in two-armed spiral systems would distinguish those potentially driven by exterior, multi-Jupiter-mass companions, and thus help identify promising targets for future direct-imaging campaigns.

We analyze a sample of\textit{ Swift} gamma-ray bursts (GRBs) with extended emissions in $\gamma$-rays and/or X-ray plateaus that may be driven by magnetars. Multi-wavelength data and multi-standards have been adopted to investigate the issue jointly. First, we find that GRBs with both extended emission and X-ray plateau satisfy a three-parameter relation between the luminosity and the end time of X-ray plateaus and the $\gamma$-ray isotropic energy as $L_X\varpropto T_a^{-1.13}E_{\gamma,iso}^{0.74}$, which is consistent with that of normal GRBs. Second, we distinguish these GRBs in the plane of magnetic field versus period of neutron star and find that almost all GRBs but GRB 211024B have reasonable periods and majority of them could be powered by magnetars. Third, we standardize the X-ray afterglows with distinct characteristics and find that the standard X-ray light curves with/without plateaus are significantly different. The standardized X-ray plateaus are similar to the mean temporal profile of magnetars. Fourth, it is verified with a K-S test that all types of GRBs except short ones have the similar distributions of redshift and isotropic energy in the observer/rest frame. GRBs with internal plateaus are significantly different from those of normal long GRBs and GRBs with external plateaus and/or extended emissions. Interestingly, the isotropic energy distributions of GRBs with internal and external plateaus are identical with those of short and long GRBs, respectively. Overall, our study can bring solid evidence that the fascinating magnetars could have multi-formation channels to account for not only short but also long GRBs with either internal or external X-ray plateaus as well.

Sulfur-bearing molecules are central to interstellar chemistry, yet their observed abundances in the gas phase remain far below cosmic expectations in dense interstellar regions. Mixed N-S-O species such as thionylimide (HNSO) are particularly relevant, as they incorporate three key biogenic elements. The $cis$ conformer of HNSO has recently been detected in the Galactic Center cloud G+0.693-0.027, but no high-resolution data for the higher energy conformer ($trans$-HNSO) had been available until now. We report the first laboratory detection and rotational spectroscopic characterization of $trans$-HNSO. Spectra were recorded with the Center for Astrochemical Studies Absorption Cell (CASAC) free-space spectrometer employing a hollow-cathode discharge source, yielding 104 assigned transitions between 200 and 530 GHz. A Watson S-reduced Hamiltonian fit reproduced the data with an rms of 40 kHz, providing accurate rotational and centrifugal distortion constants in excellent agreement with CCSD(T) predictions. Although $trans$-HNSO lies only a few kcal/mol above the $cis$ form, it has larger dipole components, making its lines particularly intense (more than 5 times brighter, assuming equal abundances) and a very promising candidate for future astronomical detection. The new measurements enable reliable frequency predictions for astronomical searches and will be added to public databases. Combined with recent evidence for tunneling-driven $trans$-to-$cis$ isomerization at cryogenic temperatures, these results open the way to test directly whether quantum tunneling governs the interstellar distribution of HNSO isomers.

An analysis is given of interacting dark energy and dark matter where the dark energy is assumed to be an ultralight axionic field with a pseudo-Nambu-Goldstone Boson potential which is in general a superposition of $N$ number of cosine terms motivated by supergravity and string models with a $U(1)$ global symmetry, where the symmetry is broken by instanton effects. The case $N=2$ is investigated in detail and a fit to cosmological data is performed where it is found that a better fit is obtained in comparison with the $N=1$ case. The fits also constrain high scale parameters, i.e., the axion decay constant which is determined to be sub-Planckian, a result consistent with string theory that disfavors trans-Planckian axion decay constant. Furthermore, the dark energy-dark matter interaction strength is constrained to be feeble, i.e., $\lambda\lesssim 4\times 10^{-6}$ m$_{\rm Pl}^{-2}$ Mpc$^{-2}$. We study possible implications of this type of potential on the Hubble tension and on the dynamics of the dark energy equation of state using the DESI-DR2 data. For the cases $N=3,4$, the analysis exhibits the phenomenon of transmutation even in the absence of coupling to dark matter, where thawing quintessence transmutes to freezing quintessence. The analysis is internally consistent in its treatment of the dark energy-dark matter interaction as it is based on an underlying Lagrangian, in contrast with several previous works where the sources are chosen in an ad hoc manner to satisfy energy conservation.

Context. The spatial distribution of haloes in the Cosmic Web encodes a wealth of information about the underlying cosmological model. These haloes can be represented as nodes of a graph, whose structural properties reflect cosmological parameters. Aims. Using our new MAKITRA suite of cosmological magneto-hydrodynamical simulations covering a total volume of $(300\,\text{Mpc})^3$ and with 21 physical model variations (including variations of $\sigma_8$ and of different models of primordial magnetic fields, PMFs), we investigate the sensitivity of network-based statistics describing the Cosmic Web to variations in cosmological and PMF scenarios. Methods. We focus on several complementary metrics that characterise the spatial distribution of dark and baryonic matter haloes: two-point correlation functions, network-centrality statistics, and counts-in-cell measurements. We first compare the halo-halo correlation functions across different cosmological models. For the network analysis, we represent haloes as vertices of the Cosmic Web and compute multiple centrality measures, whose cumulative distributions we evaluate for universes with varying PMF strengths. Finally, we quantify halo abundances within randomly placed spheres of fixed radius to assess differences between scenarios. Results. First, we find that the statistics of the centralities of the network can serve as a novel sensitive probe of the cosmological parameter $\sigma_8$. Moreover, we find that this network analysis approach can allow us to distinguish the presence of PMFs with initial strength $\approx\,4 \text{nG}$ from the scenarios with much weaker PMFs.

The ALMACAL project leverages ALMA maps of calibrator-centered fields to conduct deep mm/sub-mm surveys, enabling the detection of extragalactic sources with flux densities orders of magnitude fainter than achievable with other instruments. These faint sources are critical for refining evolutionary models, as their number counts provide key constraints. In this study, we analyzed band-3 ALMACAL maps from 606 calibrator fields, employing a novel machine learning approach to mitigate the often-overlooked bias introduced by the calibrator itself. Supported by extensive simulations, we extended 100 GHz radio AGN counts by approximately 1.5 orders of magnitude in flux density and refined constraints on dusty star-forming galaxies, reaching sensitivities as low as $\sim$180 $\mu$Jy. We have improved the sampling, compared to previous results, in the region of the dominant population transition (between dusty star-forming galaxies and radio AGN). Our results are in good agreement with model predictions.

This study forecasts the constraints on the properties of primordial black holes (PBHs) as a cold dark matter component using the galaxy clustering, weak lensing, and galaxy-galaxy lensing (i.e. $3\times2$pt) measurements from the upcoming Chinese Space Station Survey Telescope (CSST) photometric survey. Since PBHs formed via gravitational collapse in the early Universe, they can additionally affect the formation and evolution of the cosmic large-scale structure (LSS) through the ``Poisson" effect. We compute the angular power spectra for PBH-$\Lambda$CDM cosmology, and generate mock data based on the CSST instrumental and survey design. The Markov Chain Monte Carlo (MCMC) method is employed to constrain the free parameters, such as the product of the PBH fraction and mass $f_{\rm PBH}m_{\rm PBH}$ and other cosmological parameters. The systematic parameters are also included in the fitting process, such as the parameters of the baryonic effect, intrinsic alignment, galaxy bias, photometric redshift (photo-$z$) calibration, shear calibration, and noise terms. We find that the CSST 3$\times$2pt analysis can achieve tight constraints on $f_{\rm PBH}m_{\rm PBH}$, with 68% and 95% confidence levels (CLs) reaching $<10^{3.9} M_{\odot}$ and $<10^{4.7} M_{\odot}$, respectively. Additionally, the cosmological parameters, e.g. $\Omega_m$, $\sigma_8$ and $w$, can be constrained with the precisions of 3.3%, 1.7%, 13%, respectively. This indicates that the CSST 3$\times$2pt analysis is a powerful tool to advance the PBH dark matter studies in the near future.

Skew-spectra allow us to extract non-Gaussian information by taking the square of a map and finding the power spectrum of this new map with the original map. This allows us to use much of the infrastructure of power spectra and avoid the intricacies of estimating three point statistics. In this paper we present the first extension of skew-spectra to arbitrary spin-$s$ fields, as a means to extract non-Gaussian information efficiently from cosmological data sets like cosmic shear or CMB polarization. We apply the formalism to weak lensing in the context of large scale structure, and discuss different ways of combining fields to build skew-spectra, all while avoiding the problems associated with mass-mapping. We provide plots of these new statistics for $\Lambda$CDM and vary cosmological parameters.

The upcoming Vera C. Rubin Observatory Legacy Survey of Space and Time (LSST) will enable astronomers to discover rare and distant astrophysical transients. Host-galaxy association is crucial for selecting the most scientifically interesting transients for follow-up. LSST Deep Drilling Field observations will detect distant transients occurring in galaxies below the detection limits of most all-sky catalogues. Here we investigate the use of pre-existing smaller-scale, field-specific catalogues for host identification in the Deep Drilling Fields (DDFs) and a ranking of their usefulness. We have compiled a database of 70 deep catalogues that overlap with the Rubin DDFs and constructed thin catalogues to be homogenised and combined for transient-host matching. A systematic ranking of their utility is discussed and applied based on the inclusion of information such as spectroscopic redshifts and morphological information. Utilising this data against a Dark Energy Survey (DES) sample of supernovae with pre-identified hosts in the XMM-LSS and ECDFS fields, we evaluate different methods for transient-host association in terms of both accuracy and processing speed. We also apply light data-cleaning techniques to identify and remove contaminants within our associations, such as diffraction spikes and blended galaxies where the correct host cannot be determined with confidence. We use a lightweight machine learning approach in the form of extreme gradient boosting to generate confidence scores in our contaminant selections and associated metrics. Finally, we discuss the computational expense of implementation within the LSST transient alert brokers, which will require efficient, fast-paced processing to handle the large stream of survey data.

We develop a new formalism for the component separation method Spectral Matching Independent Component Analysis (SMICA) in order to include the information contained in the foregrounds beyond second-order statistics. We also develop a binned bispectrum estimator that works directly using maps of different frequency channels, capable of determining the bispectrum of multiple components at the same time, shifting the traditional approach to non-Gaussianity estimation from a cleaned map to the component separation step, for a better handling of foreground uncertainty. We test our method on 400 E and B polarization simulations based on the LiteBIRD experiment, containing the two main sources of contamination for CMB polarization experiments: polarized dust and synchrotron emission. We show that the bispectrum does not improve the precision of the power spectrum estimation or of the spectral parameters. However, we are capable of recovering the correct 3-point correlator of the foregrounds and standard constraints on primordial non-Gaussianity in a coherent multi-frequency and multi-component framework. The advantage of our approach is that it combines data in an optimal way accounting for the power spectrum and the bispectrum of the various components, which is not true for the standard approach.

Strong lensing galaxy clusters provide a unique and powerful way to test simulation-derived structure predictions that follow from $\Lambda$ Cold Dark Matter ($\Lambda$CDM) cosmology. Specifically, the relative alignments of the dark matter (DM) halo, stars, and hot intracluster gas in these clusters offer insights into how well theoretical structure predictions hold. We measure the position angles, ellipticities, and locations/centroids of the brightest cluster galaxy (BCG), the Intracluster Light (ICL), the hot Intracluster Medium (ICM), and the Core Lensing Mass (CLM) for a sample of strong lensing galaxy clusters from the Sloan Giant Arcs Survey (SGAS). We measure the shapes (position angles and ellipticities) and centroids of these distributions using ellipse-fitting methods applied to different datasets: HST WFC3 imaging for the BCG and ICL, Chandra X-ray observations for the ICM, and strong-lensing mass reconstructions for the CLM. Additionally, we incorporate ICM morphological measures to classify the dynamical state of the cluster sample. Using this multi-component approach, we constrain the shape and centroids of these distributions in this sample and evaluate the different observable components in terms of their ability to trace the gravitational potential of their respective clusters. We find that misalignments between cluster components can be explained by astrophysical processes related to cluster assembly, relaxation, and merger histories. We find that the ICL is most closely aligned with its host DM halo, as traced by the CLM distribution, in both position angle and centroid. Additionally, we find that on average the ICL and CLM are more elliptical than the ICM and BCG.

Insights into Jupiter's atmospheric dynamics are vital for understanding planetary meteorology and exoplanetary gas giant atmospheres. To study these dynamics, we require high-resolution, photometrically calibrated observations. Over the last 9 years, the Juno spacecraft's optical camera, JunoCam, has generated a unique dataset with high spatial resolution, wide coverage during perijove passes, and a long baseline. However, JunoCam lacks absolute photometric calibration, hindering quantitative analysis of the Jovian atmosphere. Using observations from the Hubble Space Telescope (HST) as a proxy for a calibrated sensor, we present a novel method for performing unpaired image-to-image translation (I2I) between JunoCam and HST, focusing on addressing the resolution discrepancy between the two sensors. Our structure-preserving I2I method, SP-I2I, incorporates explicit frequency-space constraints designed to preserve high-frequency features ensuring the retention of fine, small-scale spatial structures - essential for studying Jupiter's atmosphere. We demonstrate that state-of-the-art unpaired image-to-image translation methods are inadequate to address this problem, and, importantly, we show the broader impact of our proposed solution on relevant remote sensing data for the pansharpening task.

We study the superfluid vortex motion in the neutron star inner crust through direct three-dimensional simulations of the coupled dynamics of the vortex and the nuclear lattice. We demonstrate the pinning of an initially moving vortex to the lattice through excitation of lattice vibrations, and show that the efficiency of this process is higher for attractive than for repulsive nucleus-vortex interactions. We explore the unpinning of a vortex under the action of the applied Magnus force, and find that it is influenced by multiple parameters, including the sign of the pinning force, the lattice orientation, composition, temperature, and the energy of pinning to individual nucleus. In lattices with multiple grains, the unpinning transition is triggered inside the grains with weaker pinning, propagates along the vortex (mediated by the excited Kelvin waves) and crosses into grains with stronger pinning. This is likely to effectively decrease the critical force at which vortices unpin and to produce extended regions of unpinned vorticity. Shearing of the crust lattice (e.g., by a starquake) initiates the unpinning of the vortices that are crossing the slip plane. A close encounter of an unpinned vortex with a pinned vortex would cause the latter to unpin, perhaps initiating an unpinning avalanche of many vortices.

Data from observations of pulsars made by Murriyang, the CSIRO Parkes 64-metre radio-telescope over the last three decades are more accessible than ever before, largely due to their storage in expansive long-term archives. Containing nearly 2 million files from more than 400 Parkes pulsar projects, CSIRO's Data Access Portal is leading the global effort in making pulsar data accessible. In this article, we present the current status of the archive, and provide information about the acquisition, analysis, reduction, visualisation, preservation and dissemination of these data sets. We highlight the importance of such an archive, and present a selection of new results emanating from archival data.

Context: The streaming instability (SI) is a leading candidate for reaching solid densities sufficient to trigger the gravitational collapse needed for the formation of planetesimals. However, dust growth barriers appear to impede the ability to assemble sufficiently large dust particles to trigger strong clumping, providing a serious impediment to planetesimal formation. Aims: We aim to address the possibility to enhance dust clumping with dust growth in SI-produced structures, and to estimate the impact of the shift of the dust fragmentation threshold in regions where the SI has enhanced the dust density. Methods: We perform two-dimensional numerical simulations of the SI with a monodisperse description of dust growth, accounting for the impact of mass loading of the dust on the sound speed of the gas and dust mixture when computing dust collisional velocities. Results: Dust mass loading reduces collision velocities in high density regions, allowing dust particles to survive to larger sizes before shattering. In turn, dust clumping is boosted as particles grow in size, as long as they remain sufficiently coupled to the gas. Conclusions: This two-way synergy between dust growth and clumping, which depends on the initial dust-to-gas ratio and dust elastic properties, allows denser dust clumps to form and thus facilitates the onset of planetesimal formation.

Context. In addition to the supermassive black hole Sgr A*, the inner parsec of our Galactic center is home to numerous fruitful scientific habitats. One of these environments is the S cluster, which consists of two distinct populations: the main-sequence S stars and the dusty G objects. While the majority of the brightest S stars can be classified as young B stars, the G sources can be described as dusty objects whose nature is still under debate. Aims. In this work, we focus on the most prominent G objects in the S cluster and follow their Keplerian trajectory around Sgr A*. With this, we test the predictions based on almost two decades of monitoring of the direct vicinity of our central supermassive black hole using NACO and SINFONI, formerly mounted at the Very Large Telescope (VLT). The goal is to increase the existing data baseline for G2/DSO, D9, and X7 to get insights into their evolution on their Keplerian trajectories. In addition, we revisit the massive Young Stellar Object (YSO) X3 and scrutinize the potential impact of its environment on this highly dynamic source. Methods. The successor to the two instruments is called ERIS and offers upgraded optics and improved properties, including an enhanced spectral resolution. We utilize the IFU mode of ERIS, called SPIFFIER. We search for the Doppler-shifted Br{\gamma} emission line to rediscover peculiar objects in the S cluster using SPIFFIER with the highest available spatial plate scale of 12.5 mas. Furthermore, we will derive the Br{\gamma} luminosity of G2/DSO to inspect the degree of its change more than ten years after the pericenter passage. If present, a decrease in the Br{\gamma} luminosity of G2/DSO on its descending part of the orbit would directly impact the direction of the debate about its nature.

We characterize the sensitivity of a double point-spread function (PSF) fitting algorithm -- employing empirical, position-dependent PSF models -- for detecting companions using the infrared channel of the Wide Field Camera 3 (WFC3/IR) on the Hubble Space Telescope (HST). The observed separation distribution of known brown dwarf (BD) binaries is potentially biased towards separations larger than the angular resolution limits of current techniques. Previous imaging analyses suffer from incompleteness at separations $<2\lambda/D$; our aim is to probe within this limit to identify previously missed companions. We evaluate the performance of our technique on artificial data across 8 WFC3/IR filters and a broad range of signal-to-noise ratios (S/N), determining our ability to accurately recover injected companions and identifying the region of parameter space where false positive fits are likely. Here, we demonstrate the capability of this technique to recover companions at sub-pixel separations on the WFC3/IR detector -- below the diffraction limit in multiple filters. For F160W at a typical S/N of 75, we resolve companions separated by 0.8 pixels (104 mas, $0.759\lambda/D$) at 1.5 magnitudes contrast with $>90\%$ confidence. We achieve the closest angular resolution for any detection method with WFC3/IR imaging to date. Compared to previous BD multiplicity surveys with WFC3/IR, we achieve a 2.5$\times$ improvement in separation sensitivity at contrasts of 0-3 magnitudes in F127M. We have demonstrated that applying our improved technique to archival HST images of field BDs will thus probe down to separations of 1 au, in one of the largest high angular resolution surveys of such objects to date.

Precise cosmological inference from next-generation weak lensing surveys requires extracting non-Gaussian information beyond standard two-point statistics. We present a hybrid machine-learning (ML) framework that integrates field-level inference (FLI) with simulation-based inference (SBI) to map observed shear fields directly to cosmological parameters, eliminating the need for convergence reconstruction. The FLI network extracts rich non-Gaussian information from the shear field to produce informative features, which are then used by SBI to model the resulting complex posteriors. To mitigate noise from intrinsic galaxy shapes, we develop a blind, training-free, PCA-based shear denoising method. Tests on CSST-like mock catalogs reveal significant performance gains. The shear-based inference achieves approximately twice the cosmological constraining power in Figure of Merit (FoM) compared to the conventional convergence-based approach. Moreover, the combination of PCA denoising and ML compression can deliver a 36.4% improvement in FoM over standard shear two-point statistics. This work establishes a scalable and robust pathway for cosmological inference, unlocking the full potential of Stage-IV weak-lensing surveys.

We present a comprehensive photometric light curve and orbital period analysis of the W UMa-type contact binary EM Tuc. The O-C analysis constructed from all available eclipse timings exhibits a clear upward parabolic trend, indicating a continuous increase in the orbital period at a rate of \(dP/dt = (1.401 \pm 0.042)\times10^{-7}\,\mathrm{d\,yr^{-1}}\). This behavior is consistent with mass transfer from the less massive to the more massive star in the system, and the corresponding mass-transfer rate is estimated to be \(\dot{M} = -(4.62 \pm 1.54)\times10^{-8}\,M_\odot\,\mathrm{yr^{-1}}\). Light curve modeling with the PHysics Of Eclipsing BinariEs (PHOEBE) Python code, refined through MCMC sampling, confirms an overcontact configuration and yields a mass ratio of q=3.987. A cool photospheric starspot on the cooler component is required to reproduce the observed O'Connell asymmetry. Using Gaia DR3 parallax together with the photometric solution, the absolute masses of the components are derived as \(M_h = 0.24 \pm 0.05\,M_\odot\) and \(M_c = 0.97 \pm 0.19\,M_\odot\).

We present spectroscopic and photometric observations of supernova (SN) 2021ukt, a peculiar short-plateau object that was originally identified as a Type IIn SN and later underwent an unprecedented transition to a Type Ib (possibly Type IIb) SN. The early-time light curves of SN 2021ukt exhibit a ~25 day plateau. Such a short phase of hydrogen recombination suggests a rather thin H-rich outer envelope of the progenitor star. The relatively narrow Balmer emission lines in spectra of SN 2021ukt during the first week indicate the interaction between the expanding ejecta and the immediate circumstellar material (CSM). This H{\alpha} line is observed throughout its helium-rich ejecta-dominated phase and nebular phase, suggesting persistent interaction with a radially extended CSM profile. We explore the synthetic light-curve model among grids of parameters generated by MESA+STELLA. We also compare the spectrophotometric evolution of SN 2021ukt with several well-sampled supernovae that exhibit a short plateau and persistent ejecta-CSM interaction. An estimate of the progenitor mass of SN 2021ukt is made based on the flux ratio between [Ca II] {\lambda}{\lambda} 7291, 7324 and [O I] {\lambda}{\lambda} 6300, 6364 during its nebular phase. Our analysis suggests that the progenitor star of SN 2021ukt has a zero-age main-sequence (ZAMS) mass of about 12 solar masses, a mass of radioactive nickel-56 synthesized in the SN ejecta of about 0.04 solar masses, and a mass of the H-rich envelope of about 0.5 solar masses. This study adds to the growing sample of transitional supernovae, reinforcing evidence for a continuum of underrepresented progenitors whose evolutionary pathways lie between those of standard SN models.

Stable domain wall (DW) must decay to avoid overclose the Universe. A commonly used solution is to slightly break the PQ symmetry by introducing a bias term in the potential. In this work, we propose an alternative, symmetry-preserving mechanism: coupling the axion field to a helical primordial magnetic field (PMF) via the Chern-Simons term. Using three-dimensional lattice simulations, we evolve the DW network and demonstrate that it can successfully drive DW decay. Our quantitative results further show that the correlation length of the PMF plays a crucial role in determining the decay rate of the DW network and the resulting axion and gravitational wave radiation.

We construct a model by integrating observational results from the Milky Way and nearby galaxies to predict cloud-scale star formation rate (SFR). In the model, we first estimate the initial total mass of clumps in a cloud based on the cloud mass, and then generate the initial clump population of the cloud using the initial clump mass function. Next, we model the star formation history (SFH) of the cloud to assign an age to each clump. We then identify the clumps with ages between 2 and 5 Myr and calculate the total embedded cluster mass. Finally, we predict the SFR based on the duration of the embedded phase. The model-predicted SFR is comparable to the observed SFR, demonstrating the validity of the model.

Bayesian inference, widely used in gravitational-wave parameter estimation, depends on the choice of priors, i.e., on our previously existing knowledge. However, to investigate neutron star mergers, priors are often chosen in an agnostic way, leaving valuable information from nuclear physics and independent observations of neutron stars unused. In this work, we propose to encode information on neutron star physics into data-driven prior distributions constructed with normalizing flows, referred to as neural priors. These priors take input from constraints on the nuclear equation of state and neutron star population models. Applied to GW170817, GW190425, and GW230529, we highlight two contributions of the framework. First, we demonstrate its ability to provide source classification and to enable model selection of equation of state constraints for loud signals such as GW170817, directly from the gravitational-wave data. Second, we obtain narrower constraints on the source properties through these informed priors. As a result, the neural priors consistently recover higher luminosity distances compared to agnostic priors. Our method paves the way for classifying future ambiguous low-mass mergers observed through gravitational waves and for continuously incorporating advances in our understanding of neutron star properties into gravitational-wave data analysis.

We present a detailed analysis of Terz V 2513 (=2MASS J17334728-2719266), a poorly studied symbiotic star. Our motivation was a peculiar beating pattern in its light curves from all-sky surveys and our own observations. Using \textit{Gaia} DR3 and OGLE-IV photometry, we show that this variability arises from blending with a nearby, unrelated Mira variable (\textit{Gaia} DR3 406134544052580377 = OGLE-BLG-LPV-241930). Analysis of VPHAS+ and Pan-STARRS imaging, combined with optical and infrared spectroscopy from the Southern African Large Telescope and ESO New Technology Telescope, further reveals that the symbiotic star has been misidentified in the literature. We identify the correct counterpart as \textit{Gaia} DR3 4061345440488592896 (=OGLE-BLG-LPV-241932), a Mira with a 161-day period. Its infrared spectrum displays prominent emission lines and is remarkably similar to those of other symbiotic Miras. Based on our data and previous studies, Terz V 2513 likely experienced a symbiotic nova outburst in the past. This study highlights the importance of careful analysis of survey light curves in crowded fields and demonstrates how combining multi-wavelength photometry, spectroscopy, and high-precision \textit{Gaia} data can disentangle blended sources and accurately determine their nature.

We present atmospheric retrievals of the benchmark brown dwarf binary Luhman 16AB using high-resolution VLT/CRIRES spectra and the differentiable framework ExoJAX. We derive elemental abundances and temperature-pressure ($T$-$P$) profiles while explicitly testing the robustness of the results against major sources of systematic uncertainty. We first perform retrievals with a power-law $T$-$P$ profile and assess the sensitivity of inferred molecular abundances and C/O ratios to different CO line lists (ExoMol, HITEMP with air- and H2-broadening). We then introduce a flexible Gaussian process-based $T$-$P$ profile, allowing a non-parametric characterization of the thermal structure and a more conservative treatment of uncertainties. For both components, we infer C/O ratios of about 0.67, slightly above solar, with line list systematics at the 7 percent level emerging as the dominant source of uncertainty, whereas assumptions about $T$-$P$ parameterization or photometric variability play a lesser role. The retrieved $T$-$P$ profiles and molecular abundances are broadly consistent with atmospheric models and equilibrium chemistry. Our results establish Luhman 16AB as a key anchor for substellar C/O measurements, demonstrate the utility of flexible $T$-$P$ modeling in high-resolution retrievals, and highlight the importance of systematic tests -- particularly line list uncertainties -- for robust comparisons between brown dwarfs and giant exoplanets.

Long-range attractive fifth forces can lead to exponential instabilities in the early Universe. For fermions with a Yukawa coupling to a sufficiently light scalar mediator, rapid oscillations of the scalar field can lead to a conservative force law with fractional behaviour on sufficiently large scales. We study cosmological systems evolving under both this fractional potential and the Newtonian potential using high-resolution N-body simulations. We find that, at the same mass scale, halos that form under the fractional potential are much more dense than those that from the Newtonian potential. However, we also find that the perturbed scalar field may have large fluctuations once halo sizes become comparable to an effective Compton length, which will modify subsequent clustering and collapse.

A Ground Level Enhancement event was observed by neutron detectors designed for the registration of extensive air showers at the Experimental Complex NEVOD. The potential for that was unlocked by a recent modernization of the experimental setup that included implementation of additional channels for measuring neutron flux variation. At 10:15 UT on November 11, 2025, a sudden and significant increase in the neutron flux was detected by two installations: PRISMA-36 and URAN arrays. For the first time, a GLE has been recorded using a set of neutron detectors oriented at the extensive air shower studies. We present the measured EC NEVOD data and the results of the preliminary analysis of the observed GLE.

Dark matter haloes are typically characterised by radial density profiles with fixed forms motivated by simulations (e.g. NFW). However, simulation predictions depend on uncertain dark matter physics and baryonic modelling. Here, we present a method to constrain halo density profiles directly from observations using Exhaustive Symbolic Regression (ESR), a technique that searches the space of analytic expressions for the function that best balances accuracy and simplicity for a given dataset. We test the approach on mock weak lensing excess surface density (ESD) data of synthetic clusters with NFW profiles. Motivated by real data, we assign each ESD data point a constant fractional uncertainty and vary this uncertainty and the number of clusters to probe how data precision and sample size affect model selection. For fractional errors around 5%, ESR recovers the NFW profile even from samples as small as 20 clusters. At higher uncertainties representative of current surveys, simpler functions are favoured over NFW, though it remains competitive. This preference arises because weak lensing errors are smallest in the outskirts, causing the fits to be dominated by the outer profile. ESR therefore provides a robust, simulation-independent framework both for testing mass models and determining which features of a halo's density profile are genuinely constrained by the data.

$\delta$ Circini is known to be a massive multiple system containing a 3.9 d inner eclipsing binary in a slightly elliptical orbit exhibiting slow apsidal motion and a distant tertiary with a probable period of 1644 d. All three components of the system are O- or B-type stars. We carried out a comprehensive study of the system, based on light curves from TESS and other instruments, a new series of echelle spectra, older spectra from the ESO archive, and several VLTI interferometric observations. Due to the large amount of different types of data covering both orbits in the system, we obtained a more precise value of the long orbital period ($1603.24\pm0.19$ d) and fully determined all other orbital parameters. Although both orbits are eccentric, their period ratio is large enough for the system to be dynamically stable. The inner and outer orbits are in the same plane, which means that no Kozai-Lidov mechanism is acting in the system. Assuming solar metallicity in our MESA models, we found ages of $(4.4\pm 0.1)$, $(4.7\pm 0.2)$, and $(3.8\pm1.3)$ Myr for the primary, the secondary, and the tertiary, respectively. Our evolutionary scenario predicts that the inner eclipsing binary will merge within approximately 1.7 Myr and eventually evolve into a black hole. The distance to the system, estimated from the angular size of the outer orbit is $(809.9 \pm 1.8)$ pc, which implies that $\delta$ Cir might be located close to the centre of a stellar population ASCC 79, a subgroup of the young Circinus complex. With a total mass of $(53.04\pm0.29)$ M$_{\odot}$, $\delta$ Cir can contribute a significant fraction of the total mass of the population.

Bulk meteoritic data show isotopic variability of $slow$-neutron-capture ($s$-process) origin in a several elements heavier than Fe. One peculiar feature is that the lighter $s$-process elements (e.g., Zr and Mo) present larger anomalies than the heavier $s$-process elements (e.g., Nd and W). To address this observation, we compared Zr and Nd data to model predictions of the s-process abundances at the surface of low-mass asymptotic giant branch (AGB) stars of initial metallicity from solar to twice solar. We found that the relative magnitude of the isotopic variability between these two elements can be matched by models of AGB stars of super-solar metallicity. The match is favoured by stronger convective overshoot, leading to a deeper dredge-up of the H-rich envelope into the He-rich region, and/or a smaller (~ half than standard) mass of the region rich in the $^{13}$C nuclei that produce free neutrons via the $^{13}$C($\alpha$,n)$^{16}$O reaction. We conclude that nucleosynthesis in AGB stars can match the difference in the magnitude of the bulk meteoritic variations in Zr and Nd, provided that super-solar metallicity stars are the original site of these signatures. The AGB stars that produced such variations could have belonged to the current population of old, super-solar metallicity stars seen in the galactic solar neighbourhood.

Consecutive points in rotation curve measurements are correlated with each other, but this is usually ignored when constructing galaxy mass models. We apply the data-driven approach proposed by Posti (2022) to include the characteristic amplitude and scale length of such correlations as `nuisance parameters'. We construct mass models for $134$ galaxies from the SPARC rotation curve compilation with Navarro-Frenk-White (NFW) and pseudo-isothermal sphere (pISO) models for the dark halo. Allowing for correlations in the rotation curves generally improves the goodness of fit for both halo models, often yielding a formally good fit ($\chi^2_\mathrm{r}\approx 1$) and model uncertainties that seem more representative of the constraining power of the data. For both halo models the inference on the typical correlation amplitude and scale length are very similar and physically plausible, $\sim 20\,\mathrm{km}\,\mathrm{s}^{-1}$ and $\sim 5\,\mathrm{kpc}$, respectively. The parametric form that we use to describe the correlations is intentionally simple, and our fitting approach makes the parameters describing possible correlations prone to `absorbing' other systematic errors, so we regard these estimates as upper limits. Without allowing for correlations we find a statistical preference for the pISO over the NFW model for $88$/$134$ galaxies; this preference essentially disappears when correlations are allowed for. Accounting for correlations in rotation curves when constructing mass models fundamentally affects how they are interpreted, highlighting an important systematic uncertainty that affects evidence for cusps or cores in dark matter haloes.

Context. Stellar flares can significantly influence the atmospheres and habitability of orbiting exoplanets, especially around young and active M dwarfs. Understanding the temporally and spectrally resolved activity of such stars is essential for assessing their impact on planetary environments. Aims. We aim to examine in detail state-of-the-art concepts of flare models to identify what is missing in our understanding of energy deposition during the flare event. By comparing synthetic and observed flare spectra, we seek to determine the modelling frameworks best suited to represent flare energetics and spectral far-ultraviolet features while providing a foundation for investigating flare impacts on exoplanet atmospheres. Methods. In this work, we built the Young M Dwarfs Flare (YMDF) model utilising the combination of radiative-hydrodynamic (RHD) stellar atmosphere models with a high and low-energy electron beam and corresponding synthetic observables. These models are based on physical principles and were validated with solar and stellar observations. Results. The newly developed YMDF model reproduces the observed continuum rise in both the TESS photometric band and the FUV-A spectral range. Furthermore, the flare distributions generated within this framework show consistency with those observed in our sample of stars. Conclusions. We have developed the YMDF model as a tool to reproduce the time-dependent spectra of flaring young M dwarfs, providing a physically motivated description of their spectral and temporal evolution during flare events.

The launch of the Fermi-LAT telescope has revolutionized gamma-ray astronomy by detecting over 7,000 gamma-ray emitting objects. A major fraction of the objects are blazars of known type, and a similar fraction of objects were classified as blazars of uncertain types (BCUs). Apart from that, some of the objects were found to be unassociated with any other classes, and no information is available in other wavebands. These types of objects are classified as unassociated objects in the Fermi catalog. To classify the unassociated objects into known categories and BCUs into a known type of blazar, numerous efforts have been made using the machine learning approach. The ideal way of classification would be to have multi-wavelength temporal and spectral information, which is nearly impossible to have for this number of objects in the near future. In this paper, we focus on classifying BCUs into other types of blazars, such as FSRQs and BL Lacs. For this purpose, we have developed for the first time a deep feed-forward Artificial Neural Network (ANN) to classify them, using multi-wavelength data. The complete understanding of blazars can only be known through multi-wavelength observation, and hence, we begin with four input parameters that cover broadband information (radio, optical, X-ray fluxes, and redshift) to train the neural network, and then extend the framework by including additional parameters to examine their impact on the outcome.

To date, the Galactic interstellar radial $^{32}$S/$^{34}$S gradient has only been studied with the CS isotopologs, which may be affected by uncertainties due to the use of a single tracer. As another abundant S-bearing molecules, SO and its isotopomer $^{34}$SO could be considered as tracers of the $^{32}$S/$^{34}$S ratio. We present the first systematic observations of SO and $^{34}$SO toward a large sample of molecular clouds with accurate distances, performed with the IRAM 30 m and the 10 m Submillimeter Telescope (SMT). With the IRAM 30 m, SO $2_2-1_1$ was detected in 59 of 82 sources ($\sim$82%), and $^{34}$SO $2_2-1_1$ in 8 sources ($\sim$10%). With the SMT 10 m, SO $5_5-4_4$ was detected in 136 of 184 sources ($\sim$74%), and $^{34}$SO $5_5-4_4$ in 55 of 77 strong SO sources ($\sim$72%). SO/$^{34}$SO ratios were derived for 8 ($2_2-1_1$) and 55 ($5_5-4_4$) sources. No correlation was found between the SO/$^{34}$SO ratio and heliocentric distance or $T_k$, suggesting negligible distance and fractionation effects. Both LTE and non-LTE analyses consistently suggest that the optical depth effect is also insignificant. $^{32}$S/$^{34}$S ratios from the $2_2-1_1$ transitions follow the increasing radial trend proposed by previous CS species measurements, while those from the $5_5-4_4$ lines are systematically lower. The lower transitions of SO and $^{34}$SO may be suitable tracers of $^{32}$S/$^{34}$S, though the detections are rare. Comparisons between measurements and Galactic chemical evolution model suggest that the nucleosynthesis prescriptions need to be revised in the low-metallicity regime, but more data for the outermost Galactic regions are crucial for drawing strong conclusions.

Large-amplitude variations are commonly observed in the atmospheres of directly imaged exoplanets and brown dwarfs. VHS 1256B, the most variable known planet-mass object, exhibits a near-infrared flux change of nearly 40%, with red color and silicate features revealed in recent JWST spectra, challenging current theories. Using a general circulation model, we demonstrate that VHS 1256B's atmosphere is dominated by planetary-scale dust storms persisting for tens of days, with large patchy clouds propagating with equatorial waves. This weather pattern, distinct from the banded structures seen on solar system giants, simultaneously explains the observed spectra and critical features in the rotational light curves, including the large amplitude, irregular evolution, and wavelength dependence, as well as the variability trends observed in near-infrared color-magnitude diagrams of dusty substellar atmospheres.

The James Webb Space Telescope reveals anomalous nitrogen enrichment (high N/O ratios) in compact, star-forming galaxies, such as GN-z11 at $z\sim10$. The origin of this chemical signature provides an insight into the early star and galaxy formation processes, yet remains unclear. We performed high-resolution cosmological zoom-in simulations of massive galaxies at high redshift ($z\sim10$) in rare density peaks, incorporating various chemical evolution channels including stellar winds, core-collapse, Type Ia supernovae, and asymptotic giant branch stars. Our simulations reproduce several key features of high-redshift galaxies: (1) stars form with high efficiencies ($>0.1$) at the center of rare peak halos, creating very compact galaxies similar to GN-z11; (2) high N/O ratios emerge during the first 10-20 Myr of intense starburst, before being diluted by CCSNe; (3) multiple star clusters form in and around the galaxy with high efficiency ($\sim20\%$), some of which exhibit high N/O ratios and sodium-oxygen anti-correlations similar to those observed in local globular clusters. Although our simulations can reproduce the high log(N/O) values (up to -0.61, exceeding the solar value by 0.25 dex), they remain below the observational lower limits of GN-z11, indicating room for improvement through additional chemical evolution channels, such as supermassive stars.

We reexamined the framework used to determine the dark matter mass of a subhalo using the gravitational effects of its passage upon the stellar halo of a host. In particular, we aim to include different density distribution functions for the perturber and a non homogeneous background due to the host's halo gravitational potential. We have used a sample of K giant and RRLyrae stars based on Gaia DR3 data and two different set of simulations, to test the new formalism. From our analysis, we found that the inclusion of a nonhomogeneous background improves substantially the estimation of the subhalo dark matter mass. The methodology is not sufficiently sensitive to discriminate between different density distribution functions for the perturber, however, in the case of the observational data, the inclussion of the cloud's circular velocity is a fundamental tool to complement the analysis. The results obtained including the host halo potential agree with the independent previous measurements or with the reported value for the subhalo dark matter mass in the simulations. These results show that it is possible to measure the mass of smaller subhalos through their gravitational wake, even for subhalos closer to their host, with distances lower than 30 kpc.

We show that resonant processes during multi-field inflation can generate a large curvature perturbation on small scales. This perturbation naturally leads to the formation of primordial black holes that may constitute dark matter, as well as to the production of stochastic induced gravitational waves in the deci-Hz band. Such waves are within reach of future space-based interferometers such as LISA, DECIGO and BBO. In addition, primordial black hole binaries formed at late times produce merger gravitational waves that can be probed by the resonant cavity experiments in addition to DECIGO and BBO.

Blue straggler stars (BSSs) are exotic objects which, being the results of processes such as mass transfer, mergers or collisions, are considered key-objects to study the dynamics of their host clusters. While many studies on astrometric, spectroscopic, and photometric properties of BSSs in clusters have been conducted, there are few works in the literature regarding their pulsations and internal structure, which indeed can retain traces of their origin. In this work we computed and analysed a grid of collisional BSSs at low metallicity ($Z = 0.01\; Z_\odot$), finding that collision products present a peculiar chemical stratification that leads to periodicities in the period spacing pattern of high-order gravity modes. These seismic fingerprints provide a unique opportunity to constrain the formation pathways of BSSs in globular clusters.

Warm Inflation is a scenario in which the inflaton field dissipates its energy during inflation to maintain a subdominant constant radiation bath. Two of its remarkable features are (i) inflation can be realized even by very steep potentials and (ii) such a scenario doesn't call for a separate post-inflation reheating phase. We exploit the first feature to show that Warm Inflation can successfully take place on the very steep left wing of the Witten-O'Raifeartaigh potential while remaining in excellent agreement with current cosmological data (joint analysis of Planck, ACT and DESI). The Witten-O'Raifeartaigh potential has a flatter right wing as well, which opens up the possibility of dark energy when the field rolls along this wing. However in order to successfully realize quintessential inflation one needs to (i) normalize the two wings of the Witten-O'Raifeartaigh potential differently in order to bridge between the two extreme energy scales of inflation and dark energy, (ii) allow the quintessence field to be dissipative, which is consistent with the presence of a dissipative term in warm inflation. The dissipative dynamics of the quintessence field is needed in order to sustain slow-roll in the right wing. With these modifications, we demonstrate that the Witten-O'Raifeartaigh potential can give rise to a unified model of warm inflation (on the left wing) and transient dark energy (on the right wing).

Inferring the number of distinct components contributing to an observation, while simultaneously estimating their parameters, remains a long-standing challenge across signal processing, astrophysics, and neuroscience. Classical trans-dimensional Bayesian methods such as Reversible Jump Markov Chain Monte Carlo (RJMCMC) provide asymptotically exact inference but can be computationally expensive. Instead, modern deep learning provides a faster alternative to inference but typically assume fixed component counts, sidestepping the core challenge of trans-dimensionality. To address this, we introduce SlotFlow, a deep learning architecture for trans-dimensional amortized inference. The architecture processes time-series observations, which we represent jointly in the frequency and time domains through parallel encoders. A classifier produces a distribution over component counts K, and its MAP estimate specifies the number of slots instantiated. Each slot is parameterized by a shared conditional normalizing flow trained via permutation-invariant Hungarian matching. On sinusoidal decomposition with up to 10 overlapping components and Gaussian noise, SlotFlow achieves 99.85% cardinality accuracy and well-calibrated parameter posteriors, with systematic biases well below one posterior standard deviation. Direct comparison with RJMCMC shows close agreement in amplitude and phase, with Wasserstein distances $W_2 < 0.01$ and $< 0.03$, indicating that shared global context captures inter-component structure despite a factorized posterior. Frequency posteriors remain centered but exhibit 2-3x broader intervals, consistent with an encoder bottleneck in retaining long-baseline phase coherence. The method delivers a $\sim 10^6\times$ speedup over RJMCMC, suggesting applicability to time-critical workflows in gravitational-wave astronomy, neural spike sorting, and object-centric vision.

Gamma-ray astronomy is able to acquire large data volumes that astronomers use to draw scientific conclusions from. Ensuring the possibility of accessing and utilizing this data also after the lifetime of currently running experiments requires the use of a standardized data format. Following the data standardization format proposed by the gamma-ray astronomy community, we present 104 h of the first production of 166 h of data from the MAGIC Imaging Air Cherenkov Telescopes in standardized data format. Six datasets were processed from which three are presented, all of which have been analyzed and validated through comparison using the open-source software Gammapy and the MAGIC analysis software MARS. Furthermore, looking towards a large-scale production of standardized data and a legacy of the data taken by the MAGIC experiment, we have developed and implemented the automated database-driven MAGIC data reduction tool autoMAGIC which offers a reliable and reproducible way to produce high-level datasets. By utilizing the automatization of parameter configuration choices, the software allows for a reduction of human error as well as an acceleration in the production of standardized data. Here, we also show comparable results for data processed with manual and automatic methods.

The nature of dark matter (DM) remains a profound mystery. Macroscopic candidates, such as Fermi-balls, offer a distinct alternative to conventional particle DM, yet their low number density makes terrestrial detection challenging. In this work, we present a unified search strategy for sub-saturated Fermi-ball DM. We first revisit and significantly update astrophysical constraints from compact objects, utilizing rigorous expressions and additional white dwarf data related to ignition and subsequent supernovae. Crucially, we then explore novel signatures of Fermi-balls in future gravitational wave experiments like LISA and TianQin, performing detailed signal-to-noise ratio and Fisher matrix analyses. By combining these updated white dwarf/neutron star limits with the projected gravitational wave sensitivities, we derive the most comprehensive constraints on Fermi-ball parameter space to date, demonstrating the power of multi-messenger approaches for probing macroscopic DM.

Core collapse supernovae (CCSNe) impact many areas of astrophysics, including compact object formation and gravitational waves, but many uncertainties remain in our understanding of the evolution of their progenitors. We use the binary population synthesis code COSMIC to simulate populations of CCSNe across a wide range of metallicities and binary evolution assumptions. Our models vary the prescriptions for mass transfer stability, common envelope ejection efficiency, natal kick strength, and remnant mass-limited explodability to assess their impact on the resulting population of CCSNe. We find that reproducing the observed Type I to Type II rate requires either low common envelope efficiency or modified prescriptions for common envelope survival, highlighting the importance of stellar mergers in shaping the CCSN population. We further classify our synthetic CCSNe into subtypes and present their relative abundances using several different sets of classification criteria, highlighting the large uncertainties that persist in mapping progenitor properties to spectral classes. Finally, we present delay time distributions (DTDs) for our overall populations, separated into Type I and II, and into the full set of observed subtypes. Our DTDs show that models reproducing the observed Type I to Type II rate produce a larger fraction of late CCSNe than is expected under standard assumptions.

Molecules harbouring sulfur are thought to have played a key role in the biological processes of life on Earth. We report the first astronomical detection of a six-membered sulfur-bearing cyclic hydrocarbon in interstellar space. Observations of the Galactic center molecular cloud G+0.693-0.027 reveal the presence of 2,5-cyclohexadien-1-thione - a structural isomer of thiophenol ($c$-C$_6$H$_6$S). To allow the astronomical identification, we first performed precise laboratory measurements of the thiophenol discharge products system. These measurements, conducted in the radio band using a chirped-pulse Fourier transform microwave spectrometer, enabled us to characterize this highly polar molecular species and provided unambiguous fingerprints needed to identify this organosulfur compound in space, which now ranks as the largest interstellar sulfur-bearing molecule. These results herald the discovery of a new family of prebiotically relevant sulfur-bearing species, potentially acting as a bridge between the chemical inventory of the interstellar medium and the composition of the minor bodies of the Solar System.

Photospheric and high-velocity features (PVFs and HVFs) of Si II $\lambda$6355 and Ca II IR3 lines in supernova Ia (SN Ia) spectra provide insights into ejecta structure, energetics, and circumstellar interaction, yet their interplay remains poorly understood. We analyse a representative sample of 145 nearby SNe Ia observed within $\pm$5 days of B-band maximum light, including normal, 91T-, and 91bg-like events with measured light-curve decline rates ($\Delta m_{15}$) and Si II and Ca II line properties from the literature. We model PVF and HVF velocity distributions using Gaussian Mixture Models, compare Si II and Ca II PVF velocity distributions, assess Ca II HVF properties, and test correlations between Si II PVF velocities and $\Delta m_{15}$, with emphasis on HVF effects. For the first time, we show that the Ca II PVF velocity distribution, measured for the same events at the same phases as Si II, is predominantly unimodal, in contrast to the well-known bimodal Si II PVF distribution that supports the high-velocity/normal-velocity division. This contrast likely reflects a subclass-dependent formation depth of the Ca II line, as supported by a positive correlation ($>3.3\sigma$) between $\Delta m_{15}$ and the velocity offset between Ca II and Si II PVFs, particularly in faster-declining SNe Ia. Importantly, HVFs do not significantly bias PVF velocity distributions. A significant negative correlation ($>3.3\sigma$) between Si II PVF velocity and $\Delta m_{15}$ is found only for HVF-weak SNe Ia, consistent with more energetic explosions yielding faster ejecta, while this trend vanishes in HVF-strong events, likely due to circumstellar interaction. These results underscore the critical role of HVFs and SN Ia subclass in interpreting ejecta kinematics in both models and observations.

While mergers between massive galaxies and their dwarf satellites are well studied, the properties of dwarf-dwarf satellite mergers are not well constrained. Stellar streams trace satellite disruption and, in the dwarf galaxy regime, are predicted to provide novel constraints on low-mass galaxy evolution and dark matter. However, the mass ratios required to form these streams make them challenging to detect. We present a preview of the Stellar Stream Legacy Survey (SSLS) in the dwarf galaxy regime. The SSLS aims to produce a statistically large, homogeneous sample of stellar streams, in order to yield new constraints on galaxy formation through comparison with theory. We visually inspect dwarf galaxies using the Legacy Imaging Survey (and DECaLS footprints, r-band 29 mag arcsec-2) within 4-35 Mpc. We develop a classification metric to categorise accretion debris around dwarf galaxies, and measure the frequency of accretion features in the footprint. We present the first release of accretion features around dwarf galaxies, including 1 stream, 11 shells, and 8 asymmetric stellar halos, of which 17 constitute new identifications. We find that less than 5.07 percent of dwarfs (37/730) contain detectable accretion features, which is lower than the SSLS results for massive galaxies, and discuss a tentative shell detection bias. Our results highlight the difficulty of detecting streams around dwarf galaxies, and identify the need for improved theoretical modelling of low-mass merger morphologies. Nevertheless, they place observational constraints on hierarchical mass assembly in this regime.

There is a group of post-AGB stars that are part of a binary system and that show a significant NIR excess. These systems are known to host disks with Keplerian or quasi-Keplerian dynamics and to drive outflows of gas escaping from the rotating disk. These binary post-AGB stars can be categorized into two subclasses depending on the predominance of specific kinematic components: disk-dominated and outflow-dominated sources. We present the survey of such sources observed in CO using the IRAM-30m telescope, in which we aim to identify the molecular gas in these circumbinary-disk-containing post-AGB nebulae. We aim to analyze the mass distribution of the disk objects studied in CO. We present high-sensitivity mm-wave observations of the CO line emission from ten binary post-AGB stars. Using the derived formulation and observational data, we calculated the mass of the total gas in the CO-emitting regions of these nebulae. The logarithmic distribution of nebular masses was analyzed using a normal model that incorporates censored data, enabling a more comprehensive analysis and yielding more accurate and representative results. CO emission is detected in six post-AGB nebulae from our sample. We have significantly increased the sample of observed sources in CO lines. Some of these objects exhibit very weak molecular emission. Within the sample of disk-containing sources, the total gas mass spans a range of 1E-4 to 1E-1 Mo. The results derived from this work, along with those from a previous CO single-dish survey and interferometric data, show that this class of binary post-AGB stars exhibits a large range of nebular masses (including both the rotating disk and the expanding component), with variations exceeding a factor of 600. The typical nebular mass of these objects, accounting for both detections and non-detections through censored data analysis, is approximately 2E-3 Mo.

The detection of a very-high-energy TeV spectral component in the afterglow emission of gamma-ray bursts (GRBs) has opened a new probe into the energetics of ultra-relativistic blast waves and the nature of the circumburst environment in which they propagate. The afterglow emission is well understood as the synchrotron radiation from the shock-accelerated electrons in the medium swept up by the blast wave. The same distribution of electrons also inverse-Compton upscatters the softer synchrotron photons to produce the synchrotron self-Compton (SSC) TeV emission. Accurate modeling of this component generally requires a computationally expensive numerical treatment, which makes it impractical when fitting to observations using Markov Chain Monte Carlo (MCMC) methods. Simpler analytical formalisms are often limited to broken power-law solutions and some predict an artificially high Compton-Y parameter. Here we present a semi-analytic framework for a spherical blast wave that accounts for adiabatic cooling and expansion, photon escape, and equal-arrival-time-surface integration, in addition to Klein-Nishina effects. Our treatment produces the broadband afterglow spectrum and its temporal evolution at par with results obtained from more sophisticated kinetic calculations. We fit our model to the afterglow observations of the TeV bright GRB\,190114C using MCMC, and find an energetic blast wave with kinetic energy $E_{k, \rm iso} = 9.1^{+7.41}_{-3.13} \times 10^{54} \, \rm erg$ propagating inside a radially stratified external medium with number density $n(r)\propto r^{-k}$ and $k=1.67^{+0.09}_{-0.10}$. A shallower external medium density profile ($k<2$) departs from the canonical approximation of a steady wind ($k=2$) from the progenitor star and may indicate a non-steady wind or a transition to an interstellar medium.

We present the results of Hi line observations towards 26 Active Galactic Nuclei (AGN)-hosting and one star-forming dwarf galaxies (Mstar < 10^9.5 Msun) with the 19-beam spectral line receiver of FAST at 1.4 GHz. Our FAST observed targets are combined with other AGN-hosting dwarf galaxies covered in the ALFALFA footprint to form a more comprehensive sample. Utilizing the information from optical surveys, we further divide them into isolated and accompanied subsamples by their vicinity of nearby massive galaxies. We compare the Hi gas abundance and star-forming rate (SFR) between the subsamples to assess the role of internal and external processes that may regulate the gas content in dwarf galaxies. As a result, we find that AGN are more commonly identified in accompanied dwarf galaxies than in their isolated counterparts. Meanwhile, AGN-hosting dwarf galaxies have slightly but significant lower Hi mass fraction relatively to the non-AGN control sample in accompanied dwarf galaxies. On the other hand, we find a decreasing SFR in AGN-hosting dwarf galaxies towards denser environments, as well as an extremely low incidence of quenched isolated dwarfs within both AGN and non-AGN subsamples. These results indicate that although these AGN could potentially regulate the gas reservoir of dwarf galaxies, environmental effects are likely the dominant quenching mechanism in the low-mass universe.

HV 11417 is a candidate Thorne-Żytkow Object, a red supergiant with a neutron star core, located within the Small Magellanic Cloud (SMC). Previous studies have questioned, using Gaia DR2 data, whether HV 11417 was truly located at the distance of the SMC or was instead a foreground star. However, the proper motion measurement uncertainties for HV 11417 in DR2 were high. In this work, we use Gaia DR3 data to show that HV 11417 is very likely to be a true member of the SMC. We further analyze the kinematics of HV 11417 relative to its local environment, and compare it to populations of massive and evolved stars in the SMC. We find HV 11417 has a local transverse velocity of $52\pm15$ km/s, and thus qualifies as a runaway star (v$_\mathrm{loc}\geq$ 30 km/s). This runaway classification does not conclusively prove its nature as a TŻO, particularly given results from recent TŻO models, but does indicate that HV 11417 experienced a kinematic disruption in its evolution.

This thesis presents an innovative framework for the automated detection and characterization of galactic bars, pivotal structures in spiral galaxies, using the YOLO-OBB (You Only Look Once with Oriented Bounding Boxes) model. Traditional methods for identifying bars are often labor-intensive and subjective, limiting their scalability for large astronomical surveys. To address this, a synthetic dataset of 1,000 barred spiral galaxy images was generated, incorporating realistic components such as disks, bars, bulges, spiral arms, stars, and observational noise, modeled through Gaussian, Ferrers, and Sersic functions. The YOLO-OBB model, trained on this dataset for six epochs, achieved robust validation metrics, including a precision of 0.93745, recall of 0.85, and mean Average Precision (mAP50) of 0.94173. Applied to 10 real galaxy images, the model extracted physical parameters, such as bar lengths ranging from 2.27 to 9.70 kpc and orientations from 13.41$^\circ$ to 134.11$^\circ$, with detection confidences between 0.26 and 0.68. These measurements, validated through pixel-to-kiloparsec conversions, align with established bar sizes, demonstrating the model's reliability. The methodology's scalability and interpretability enable efficient analysis of complex galaxy morphologies, particularly for dwarf galaxies and varied orientations. Future research aims to expand the dataset to 5,000 galaxies and integrate the Tremaine-Weinberg method to measure bar pattern speeds, enhancing insights into galaxy dynamics and evolution. This work advances automated morphological analysis, offering a transformative tool for large-scale astronomical studies.

Context: The VISTA Variables in the Via Lactea (VVV) and its extension (VVVX) are near-infrared surveys mapping the Galactic bulge and adjacent disk. These data have enabled the discovery of numerous star clusters obscured by high and spatially variable extinction. Most previous searches relied on visual inspection of individual tiles, which is inefficient and biased against faint or low-density systems. Aims: We aim to develop an automated, homogeneous algorithm for systematic cluster detection across different surveys. Here, we apply our method to VVVX data covering low-latitude regions of the Galactic bulge and disk, affected by extinction and crowding. Methods: We introduce the Consensus-based Algorithm for Nonparametric Detection of Star Clusters (CANDiSC), which integrates kernel density estimation, the Density-Based Spatial Clustering of Applications with Noise (DBSCAN), and nearest-neighbour density estimation within a consensus framework. A stellar overdensity is classified as a candidate if identified by at least two of these methods. We apply CANDiSC to 680 tiles in the VVVX PSF photometric catalogue, covering approximately 1100 square degrees. Results: We detect 163 stellar overdensities, of which 118 are known clusters. Cross-matching with recent catalogues yields five additional matches, leaving 40 likely new candidates absent from existing compilations. The estimated false-positive rate is below 5 percent. Conclusions: CANDiSC offers a robust and scalable approach for detecting stellar clusters in deep near-infrared surveys, successfully recovering known systems and revealing new candidates in the obscured and crowded regions of the Galactic plane.

We present a 9.3-sigma detection of the pairwise kinematic Sunyaev-Zeldovich (kSZ) effect by combining a sample of 913,286 Luminous Red Galaxies (LRGs) from the Dark Energy Spectroscopic Instrument Data Release 1 (DESI DR1) catalog and co-added Atacama Cosmology Telescope (ACT DR6) and Planck cosmic microwave background (CMB) temperature maps. This represents the highest-significance pairwise kSZ measurement to date. The analysis uses three ACT CMB temperature maps: co-added 150 GHz, total frequency maps, and a component-separated Internal Linear Combination (ILC) map, all of which cover 19,000 square degrees of the sky from Advanced ACTPol observations conducted between 2017 and 2022. Comparison of the results of these three maps serves as a consistency check for potential foreground contamination that may depend on the observation frequency. An estimate of the best-fit mass-averaged optical depth is obtained by comparing the pairwise kSZ curve with the linear-theory prediction of the pairwise velocity under the best-fit Planck cosmology, and is compared with predictions from simulations. This estimate serves as a reference point for future comparisons with thermal SZ-derived optical depth measurements for the same DESI cluster samples, which will be presented in a companion paper. Finally, we employ a machine-learning approach trained on simulations to estimate the optical depth for 456,803 DESI LRG-identified clusters within the simulated mass range (greater than about 1e13 solar masses). These are combined with the measured kSZ signal to infer the individual cluster peculiar velocities, providing the opportunity to constrain the behavior of gravity and the dark sector over a range of cosmic scales and epochs.

We propose a cosmological framework in which neutrino masses evolve dynamically through coupling with a scalar field that simultaneously drives inflation. The neutrino mass is modeled as a power-law, exponential, or hybrid function of the scalar field, yielding an effective potential that includes neutrino backreaction. Starting from the Einstein-Hilbert action in a flat FLRW background, we derive the modified Friedmann and Klein Gordon equations incorporating this coupling. Using the Fermi-Dirac integrals, we account for the continuous transition of neutrinos from relativistic to non-relativistic regimes. The inflationary dynamics are analyzed via the slow roll parameters derived from the effective potential. Our results show that the scalar neutrino coupling alters the potential slope and curvature, thereby influencing the duration of inflation. The hybrid coupling form provides the most flexible realization, unifying neutrino mass generation with early universe inflation within a single scalar field framework.

Gamma-ray bursts (GRBs), among the most compelling astrophysical phenomena, are potential candidates for exploring the evolution of energy distribution among magnetic fields and particles through multiwavelength observations. The fraction of energy transferred between particles and the magnetic field is governed by microphysical parameters, typically assumed to be constant during relativistic shocks but may in fact vary with time. In this work, we derive the light curves and closure relations (CRs) of the synchrotron-self Compton (SSC) process from the external reverse shock (RS) with variations of microphysical parameters in a homogeneous and stellar-wind medium. We consider the evolution of the RS in the thick- and thin-shell regimes. We demonstrate that, depending on the microphysical parameters, this process can mimic plateau phases and produce temporal decay indices steeper than those predicted by high-latitude emission alone. The current model is employed to examine the evolution of the spectral and temporal indices of GRBs reported in the Second Fermi-LAT Gamma-ray Burst Catalog (2FLGC) and bursts detected at very high energies, using Markov Chain Monte Carlo (MCMC) simulations.

A question that continues to perplex astronomers is the formation of tight stellar binaries. There is too much angular momentum in a collapsing and fragmenting protostellar cloud to form a stellar binary in situ with a separation less than an AU, yet thousands of these short-period binaries have been discovered. One indication of a binary's formation is the angle between the stellar spin and orbital axes -- its obliquity. The classical method for determining projtected stellar obliquity is the Rossiter-McLaughlin effect. This method has been applied to over 100 hot Jupiters, yet only a handful of stellar binaries. Of the binary systems with measured projected obliquities, even fewer have measured 3D obliquities. In this paper, we add five more short-period binary 3D obliquity measurements to the sample that previously consisted of a single system. We present Rossiter-McLaughlin measurements for EBLM J0239-20, EBLM J0941-31, EBLM 1037-25, EBLM 1141-37, and EBLM J2025-45. These systems consist of an M-dwarf eclipsing an F/G type primary. We combined CORALIE and HARPS spectroscopy with TESS photometry of primary and secondary eclipses. We show that even though the sky-projected obliquities seem to be aligned, there is modest but non-zero spin-orbit misalignment ($\psi$ between 5 and 20$^{\circ}$). Our primary stars straddle the Kraft break at $\sim 6250K$. Finally, we derive the M-dwarf masses and radii to precisions better than 3\%. With the exception of EBLM J0941-31, each system has an inflated radius greater than $5\sigma$ from the expected radius from stellar models.

We present a new measurement of the Hubble constant, independent of standard rulers and robust to pre-recombination modifications such as Early Dark Energy (EDE), obtained by calibrating the total energy density of the Universe. We start using the present-day photon density as an anchor, and use the baryon-to-photon ratio from Big Bang Nucleosynthesis based measurements and the baryon-to-matter ratio from the baryons' imprint on galaxy clustering to translate to a physical matter density at present day. We then compare this to measurements of the ratio of the matter density to the critical density ($\Omega_{\mathrm{m}}$), calculated using the relative positions of the baryon acoustic oscillations, to measure the critical density of the universe and hence $H_0$. The important measurements of the evolution of the energy density all happen at low redshift, so we consider this a low-redshift measurement. We validate our method both on a suite of $N$-body mocks and on noiseless theory vectors generated across a wide range of Hubble parameters in both $\Lambda$CDM and EDE cosmologies. Using DESI DR1 data combined with the angular CMB acoustic scale and the latest BBN constraints, we find $H_0 = 69.0 \pm 2.5$ km s$^{-1}$ Mpc$^{-1}$, consistent with existing early and late-time determinations of the Hubble constant. We consider the impact of non-standard dark energy evolution on our measurement. Future data, including that from further iterations of DESI and from Euclid, will add to these results providing a powerful test of the Hubble tension.

The metallicity structure of stellar halos encodes the fossil record of galaxy assembly, tracing the chemical evolution and dynamical imprint of past mergers. Using five Milky Way-mass halos from the Aquarius simulations, we introduce an information-theoretic framework to quantify spatial-chemical correlations through the mutual information (MI) between angular position and metallicity. We divide stars in each halo into high- and low-metallicity populations based on their median metallicity and examine their metallicity distribution functions (MDFs), spatial anisotropies, and angular-metallicity couplings as a function of galactocentric radius. The MDFs exhibit remarkable diversity, ranging from single-peaked distributions dominated by one or two massive progenitors to broad or bimodal forms shaped by multiple accretion events, revealing the stochastic nature of halo assembly. The low-metallicity stars, primarily contributed by disrupted satellites, display higher spatial anisotropy and stronger angular clustering than their metal-rich counterparts. After removing bound satellites, anisotropy decreases significantly, yet high-metallicity stars remain marginally more anisotropic, reflecting the lingering debris of massive, centrally deposited progenitors. The mutual information between angular position and metallicity increases with radius before saturating in the outskirts, with the difference between the data and randomized controls confined mainly to the inner halo signifying residual spatial-chemical coupling driven by incomplete phase mixing. Our results demonstrate that information-theoretic diagnostics provide a powerful and intuitive way to quantify the chemical complexity of stellar halos and offer a promising route to compare simulations with forthcoming high-dimensional Galactic survey data.

Galaxy clustering constrains the baryon fraction Omega_b/Omega_m through the amplitude of baryon acoustic oscillations and the suppression of perturbations entering the horizon before recombination. This produces a different pre-recombination distribution of baryons and dark matter. After recombination, the gravitational potential responds to both components in proportion to their mass, allowing robust measurement of the baryon fraction. This is independent of new-physics scenarios altering the recombination background (e.g. Early Dark Energy). The accuracy of such measurements does, however, depend on how baryons and CDM are modeled in the power spectrum. Previous template-based splitting relied on approximate transfer functions that neglected part of information. We present a new method that embeds an extra parameter controlling the balance between baryons and dark matter in the growth terms of the perturbation equations in the CAMB Boltzmann solver. This approach captures the baryonic suppression of CDM prior to recombination, avoids inconsistencies, and yields a clean parametrization of the baryon fraction in the linear power spectrum, separating out the simple physics of growth due to the combined matter potential. We implement this framework in an analysis pipeline using Effective Field Theory of Large-Scale Structure with HOD-informed priors and validate it against noiseless LCDM and EDE cosmologies with DESI-like errors. The new scheme achieves comparable precision to previous splitting while reducing systematic biases, providing a more robust way to baryon-fraction measurements. In combination with BBN constraints on the baryon density and Alcock-Paczynski estimates of the matter density, these results strengthen the use of baryon fraction measurements to derive a Hubble constant from energy densities, with future DESI and Euclid data expected to deliver competitive constraints.

Recent results from DESI BAO analyses suggest that dark energy may not be a cosmological constant and is in fact dynamical. Furthermore, the data suggest that the equation of state may have been in the phantom regime in the distant past, recently undergoing a phantom crossing. In this work, we investigate whether this preference can be realized within a kinetically mixed axion-dilaton (KMIX) quintessence model, a string-motivated system in which an axion-like field couples exponentially to a dilaton-like (moduli) field. Crucially, KMIX can appear phantom in a standard Chevallier-Polarski-Linder (CPL) based analysis. To confront the model with data, we develop a fast pipeline based on normalizing flows that (i) learns a theory-informed prior on $(w_0,w_a)$ from KMIX realizations and (ii) provides an inverse mapping from CPL parameters back to the physical KMIX parameters. By importance-sampling pre-computed CPL chains using this framework, we effectively transform generic phenomenological constraints into direct, computationally efficient constraints on the underlying KMIX theory, avoiding the prohibitive cost of full parameter space exploration. Applied to Planck+DESI DR2 BAO measurements, our framework finds support for KMIX at $2.5\sigma$ compared to the base CPL fit at $3.1\sigma$, demonstrating that KMIX may account for the DESI preference without invoking true phantom behavior. When additionally including Type Ia supernovae data, we find that the preference remains above $3\sigma$ for Union3 and DES Y5, but drops to $2.1\sigma$ with Pantheon+. The latter, combined with the DESI full-shape power spectrum and bispectrum data, further reduces the preference to $1.7\sigma$. Ultimately, should the DESI deviation persist with future data, KMIX may offer a theoretically well-motivated explanation for the phantom-like signatures inferred from phenomenological fits.

The Galactic Center excess (GCE) of GeV $\gamma$ rays may hint at dark matter (DM), yet its origin remains debated. Motivated by this, we survey weakly interacting massive particle (WIMP) models that can fit the GCE while satisfying relic-density, direct-detection (DD), and indirect-detection (ID) bounds. We group candidates into hadronic (Higgs portals; simplified scalar/vector mediators), leptonic ($U(1)_{L_i-L_j}$), and mixed ($U(1)_{B-L}$, $Z$-portal) classes. Across all cases, present DD and dwarf-spheroidal $\gamma$-ray limits exclude wide regions, leaving mainly narrow resonant funnels with $m_{\rm DM}\!\simeq\! m_{\rm med}/2$ and portal couplings $\ll 1$. In hadronic setups, scalar and vector Higgs portals survive only in a thin strip near $m_h/2\simeq62.5$ GeV with portal couplings $\sim 10^{-4}$, while the Dirac Higgs and $Z$ portals are essentially excluded. The UV-complete vector Higgs portal retains resonant bands whose viable portal strength depends on the mixing angle. Simplified scalars allow small windows for complex-scalar or vector DM; Dirac DM is strongly disfavored, whereas a pseudoscalar with Dirac DM remains viable over a broader parameter range. For a simplified $Z'$ mediator, a pure vector coupling leaves only a marginal region, while pure axial is excluded by DD/ID bounds. In leptonic scenarios, inverse-Compton emission is essential: $L_\mu-L_e$ (and, to a lesser extent, $B\!-\!L$) fits the GCE with near-thermal cross sections, while $L_\mu-L_\tau$ is disfavored. Overall, viable WIMP explanations are constrained to finely tuned resonant regime, with leptophilic vectors and pseudoscalar portals emerging as the most robust options.

We present a new classical mechanism for nucleation of bubbles of true vacuum. The mechanism arises when dense boson stars form in the false vacuum. As the boson stars collapse due to attractive self-interactions, the field inside the stars core is enhanced beyond the potential barrier. Subsequently the stars explode as true vacuum bubbles, and induce a cosmological phase transition. The mechanism raises the possibility that a vacuum that is stable against quantum tunneling can be vulnerable to ``astrophysical'' processes.

As the hunt for dark matter progresses, recently there have been advances in the search for heavy dark matter with a mass well above a TeV. We show the importance of properly modeling the local dark matter velocity distribution, beyond the standard Maxwellian halo model, and in particular how the dynamics of the Large Magellanic Cloud and Milky Way may impact heavy dark matter searches. We introduce some new computational techniques for accurately computing the dark matter flux and the associated detector response. As a specific example, we examine the effect of the Large Magellanic Cloud on heavy dark matter bounds obtained from experiments searching for cosmic rays and magnetic monopoles using plastic etch detectors at the Ohya Mine and aboard the Skylab Space Station.

We present GANDALF, a JAX-based spectral solver for Kinetic Reduced MHD (KRMHD) turbulence designed to lower infrastructure barriers to plasma turbulence research. Existing production codes require specialized HPC infrastructure and compilation expertise, limiting participation to well-resourced institutions. GANDALF addresses this barrier by leveraging JAX's hardware abstraction to run transparently on laptops, desktop GPUs, and Apple Silicon without modification, enabling single-command installation via pip. We employ Fourier spectral methods for spatial discretization and Hermite spectral basis for velocity space, combined with an exponential integrating factor method that exactly propagates linear Alfvén waves, eliminating associated numerical stiffness. Verification demonstrates research-grade accuracy: linear Alfvén waves achieve machine precision (~10^{-15} relative error), the Orszag-Tang vortex conserves energy to 10^{-6} over two Alfvén times, and driven turbulence reproduces the expected k_perp^{-5/3} cascade spectrum. GANDALF enables rapid prototyping, parameter surveys, and educational applications on commodity hardware. The code complements rather than replaces established solvers like AstroGK and Viriato, prioritizing accessibility for researchers without HPC resources. By removing infrastructure barriers while maintaining spectral accuracy, GANDALF broadens participation in fundamental plasma turbulence research, particularly benefiting students, small research groups, and institutions in developing regions.

Black hole binaries with small mass ratios will be important sources for the forthcoming Laser Interferometer Space Antenna (LISA) mission. Models of such binaries also serve as useful tools for understanding the dynamics of compact binary systems and the gravitational waves they emit. Using an eccentric Ori-Thorne procedure developed in previous work, we build worldlines that describe the full inspiral and plunge of a small body on an initially eccentric orbit of a Kerr black hole. We now calculate the gravitational waves associated with these trajectories using a code that solves the Teukolsky equation in the time domain. The final cycles of these waveforms, the ringdown, contains a superposition of Kerr quasinormal modes followed by a power-law tail. In this paper, we study how a binary's eccentricity and orbital anomaly angle affect the excitation of both quasinormal modes and late-time tails. We find that the relative excitation of quasinormal modes varies in an important and interesting way with these parameters. For some anomaly angles, the relative excitations of quasinormal modes are essentially indistinguishable from those excited in quasi-circular coalescences. Consistent with other recent studies, we find that eccentricity tends to amplify the late-time power-law tail, though the amount of this amplification varies significantly with orbital anomaly. We thus find that eccentricity has an important impact on the late-time coalescence waveform, but the interplay of eccentricity and orbit anomaly complicates this impact.

The multi-messenger detection of the binary neutron star (NS) merger GW170817 has revolutionized the field of gravitational wave (GW) astronomy. However, several important questions remain to be answered. One of these is the nature of the compact remnant leftover by GW170817 (short- or long-lived NS versus black hole). A key goal going forward is to understand the diversity of NS-NS merger remnants, and how such diversity maps onto their viability as gamma-ray burst (GRB) central engines. Here, we present a study aimed at assessing the sensitivity of triggered searches for intermediate-duration, post-merger GWs powered by long-lived GRB remnants using networks of current and future ground-based GW detectors and the Cross-Correlation Algorithm (CoCoA). We develop a Python-based framework to efficiently estimate CoCoA distance horizons for a broad range of post merger secular bar-mode waveforms and for different GW detector networks. This framework can be used to identify the most promising regions of parameter space in which to concentrate search efforts, helping design future search strategies to optimally balance search sensitivity and related parameter space gridding schema against computational cost.

Parker Solar Probe (PSP) observed a high speed stream near the Sun ($\sim 9.8 R_\odot$) in March 2025. As this stream was observed near the Sun, it allowed for an unparalleled opportunity to observe pristine, coronal hole wind with little evolution (expansion, stream interaction, etc) effects impacting its properties. Through an ensemble of magnetic connectivity analysis utilizing Potential Field Source Surface (PFSS) modeling and ballistic propagation, we make estimates of the footpoints, and corresponding source region parameters, associated with the stream. We then look at how the low variability regions (small gradient in the in-situ $B_r$) are related to the variability in the field strength at their source ($B_0$). We find that about half of these periods are associated with low source region variability. Lastly, we examine the low $\delta B / B$ periods between switchback patches and similarly find that they show statistically less variability in their associated $B_0$ value than their switchback patch counterparts. We believe that these results point to a solar source of these ``low-variability" periods, that warrants further investigation with composition diagnostics and more complex modeling techniques.

In compact stellar environments, the stability of dense QCD matter requires the simultaneous fulfillment of charge neutrality and beta equilibrium. In this work, we study how temperature and finite chemical potential affect QCD topology and axion properties within this medium, analyzing both cases with and without the charge neutrality condition. Our results show that the topological susceptibility and axion properties are highly sensitive to the critical behavior of the chiral phase transition in both cases. In particular, the axion mass is strongly suppressed near the transition, while the axion self-coupling constant develops a pronounced peak whose magnitude depends on the temperature and density of the medium. Remarkably, around the critical point at $T\simeq70$ MeV and $\mu\simeq346$ MeV, the self-coupling constant is enhanced by more than a factor of seven compared to its vacuum value, a feature that to the best of our knowledge has not been reported in previous studies. Such a strong amplification at the phase boundary indicates that axion-mediated interactions could play an important role in shaping the structure and stability of compact stars, with potential implications for their evolution and observable astrophysical signatures.

We show that General Relativity and other geometrical theories can be viewed as a degenerate Otto cycle with only heat-exchange legs in emergent gravity. Including work-producing legs yields controlled violations of local Lorentz invariance and energy-momentum conservation, which produce late-time cosmological acceleration. Implications for the cosmological constant problem, structure formation and local observations are discussed.

We study the retrograde second caustics of extremal Kerr black holes, where the intensity of the light beam is infinitely magnified. We find that the caustics of different polarized beams are split by as much as $10^{-3}$rad by an external black hole for a suitable range of parameters. A lensing black hole at several lys away separates the polarized beams about $10^{12}$m apart. This splitting is larger than the radius of the Earth. Therefore, an observer on Earth would see different circularly polarized light according to their location. The polarization will change while the detector is wandering around. Thus, the polarization of light beams can be an important quantity in retrolensing observations.

Bayesian computational strategies for inference can be inefficient in approximating the posterior distribution in models that exhibit some form of periodicity. This is because the probability mass of the marginal posterior distribution of the parameter representing the period is usually highly concentrated in a very small region of the parameter space. Therefore, it is necessary to provide as much information as possible to the inference method through the parameter prior distribution. We intend to show that it is possible to construct a prior distribution from the data by fitting a Gaussian process (GP) with a periodic kernel. More specifically, we want to show that it is possible to approximate the marginal posterior distribution of the hyperparameter corresponding to the period in the kernel. Subsequently, this distribution can be used as a prior distribution for the inference method. We use an adaptive importance sampling method to approximate the posterior distribution of the hyperparameters of the GP. Then, we use the marginal posterior distribution of the hyperparameter related to the periodicity in order to construct a prior distribution for the period of the parametric model. This workflow is empirical Bayes, implemented as a modular (cut) transfer of a GP posterior for the period to the parametric model. We applied the proposed methodology to both synthetic and real data. We approximated the posterior distribution of the period of the GP kernel and then passed it forward as a posterior-as-prior with no feedback. Finally, we analyzed its impact on the marginal posterior distribution.

We investigate the charging process of a rotating Kerr black hole of mass $M$ and angular momentum $J$ immersed in a stationary, axisymmetric, asymptotically uniform magnetic field of strength $B_{0}$. In Wald's classic analysis (Wald 1974), which was based on the assumption of vanishing injection energy, the black hole was predicted to acquire a universal "saturation charge" $Q_{\mathrm{w}}=2B_{0}J$. However, the physical mechanism that sets the saturation charge must ultimately be governed by the competition between the absorption rates of positively and negatively charged particles. Motivated by this observation, we revisit the problem in the framework of a simple accretion model, where two dilute, equivalent fluxes of charged particles of opposite signs are injected from infinity along the magnetic field lines. The problem then reduces to that of individual particle motion in the electromagnetic field of the magnetized Kerr black hole. Using a combination of numerical and analytical tools, we determine the domains of absorption and establish both lower and upper bounds on the corresponding absorption cross sections. At $Q=Q_\mathrm{w}$ these bounds reveal a systematic difference between the two charge signs. In particular, for sufficiently strong magnetic fields, the lower bound on the absorption cross section for the "attracted" charge exceeds the upper bound for the "repelled" one. This charge accretion imbalance (which we find to become extreme at the limit of large $B_{0}$) indicates a persistent net charge accretion at $Q=Q_{\mathrm{w}}$, implying that the actual saturation charge must differ from Wald's charge $Q_{\mathrm{w}}$.

Spacetimes in general relativity can be uniquely decomposed into a set of multipole moments. Given the usefulness of moments in the categorisation of radiation patterns, tidal deformations, and other phenomena associated with compact objects, a number of studies have explored their construction in beyond-Einstein theories of gravity. It is shown here that uniqueness does not necessarily extend across theories: by comparing a few static and spherically-symmetric solutions in different theories, we find that two distinct objects can possess the same Geroch-Hansen moments. Moreover, two metrics can match and yet take different moments. Implications of this result are explored in the context of black-hole shadows and ``universal'' relations hinging on moment computations.

Misalignment dynamics, the non-equilibrium evolution of a scalar (or pseudoscalar) condensate in a potential landscape, broadly describes a solution to the strong CP problem, a mechanism for cold dark matter production and (pre) reheating post inflation. Often, radiative corrections are included phenomenologically by replacing the potential by the effective potential which is a \emph{static quantity}, its usefulness is restricted to (near) equilibrium situations. We study the misalignment dynamics of a scalar condensate Yukawa coupled to $N_f$ fermions in a manifestly energy conserving, fully renormalized Hamiltonian framework. A large $N_f$ limit allows us to focus on the fermion degrees of freedom, which yield a negative contribution to the effective potential, a radiatively induced instability and ultraviolet divergent field renormalization. We introduce an adiabatic basis and an adiabatic expansion that embodies the derivative expansion in the effective action, the zeroth order is identified with the effective potential, higher orders account for the derivative expansion including field renormalization and describe profuse particle production. Energy conserving dynamics leads to the conjecture of emergent asymptotic highly excited stationary states with a distribution function $n_k(\infty)\propto 1/k^6$ and an extensive entropy which is identified with an entanglement entropy. Subtle aspects of renormalization associated with the initial value problem are analyzed and resolved. Possible new manifestations of asymptotic spontaneous symmetry breaking (SSB) as a consequence of the dynamics even in absence of tree level (SSB), and cosmological inferences are discussed.

With increasing quantity and quality of solar observations, it becomes essential to account for three-dimensional heterogeneities in wave modeling for seismic data interpretation. In this context, we present a 3D solver of the time-harmonic adiabatic stellar oscillation equations without background flows on a domain consisting of the Sun and its photosphere. The background medium consists of 3D heterogeneities on top of a radial strongly-stratified standard solar model. The oscillation equations are solved with the Hybridizable Discontinuous Galerkin (HDG) method, considering a first-order formulation in terms of the vector displacement and the pressure perturbation. This method combines the high-order accuracy and the parallelism of DG methods while yielding smaller linear systems. These are solved with a direct solver, with block low-rank compression and mixed-precision arithmetic to reduce memory footprint. The trade-off between compression and solution accuracy is investigated, and our 3D solver is validated by comparing with resolution under axial symmetry for solar backgrounds. The capacity of the solver is illustrated with wave speed heterogeneities characteristic of two physical phenomena: active regions and convection. We show the importance of global 3D gravito-acoustic wave simulations, in particular when the amplitudes of the perturbations are strong and their effect on the wavefield cannot be estimated by linear approximations.

Infinite towers of higher-order corrections to General Relativity have been proposed as a mechanism to resolve singularities in early-universe cosmology and black holes, in a variety of settings. In this work, we consider an infinite tower of higher-order Proca corrections inspired by dimensional regularizations of Lovelock invariants. We find that the Big Bang singularity present in General Relativity is replaced by an inflationary epoch. Furthermore, the Lovelock-Proca tower allows for regular planar black hole solutions and spherically symmetric black holes with primary hair.

Neutron stars can be regarded as natural laboratories that enable us to investigate nuclear matter properties under extreme conditions that are otherwise impossible to access in terrestrial experiments. Astrophysical observations of neutron stars provide invaluable information on existing nuclear interaction models and equations of state (EoSs) at various densities. Most studies of neutron star structure employ the Tolman-Oppenheimer-Volkoff (TOV) equation which describes spherically symmetric, non-rotating stars in hydrostatic equilibrium. However, since neutron stars rotate fast, they could experience significant centrifugal deformation, and axially-symmetric calculations are required for accurate description of internal structure. The Komatsu-Eriguchi-Hachisu (KEH) method is well known for modeling rapidly-rotating compact objects in a fully general relativistic manner. In this contribution, we report results of KEH calculations for rapidly-rotating neutron stars using EoSs based on Gogny-type finite-range effective nucleon-nucleon interactions. Our results show that the mass-radius relation systematically changes with increasing angular velocity, highlighting the importance of including rotational effects when confronting theoretical EoSs with observational data.

We investigate two different definitions of a scalar field effective potential in quantum field theory in de Sitter spacetime: the standard textbook definition, and the constraint effective potential proposed by O'Raifeartaigh et al. in 1986. While these definitions are equivalent in Minkowski spacetime, they differ significantly in de Sitter. We demonstrate this by computing them both explicitly at one-loop order in perturbation theory. It is well known that the perturbative expansion of the standard effective potential fails converge for light fields. In contrast, the constraint effective potential does not suffer from this infrared problem, and it can therefore be computed using perturbation theory. We discuss the physical interpretation of the two effective potentials. In particular, we provide evidence supporting an earlier conjecture that the constraint effective potential is the correct one to use in the stochastic Starobinsky-Yokoyama theory.

We present a comprehensive study addressing pile-up effects in single photoelectron counting with R-11265 Hamamatsu multi-anode photomultiplier tubes (MAPMTs) equipped with the SPACIROC-3 ASIC. Extended dead time in the electronics causes saturation and quenching of the counting rate, an effect we counter by inverting the pile-up plot once the double pulse resolution is determined. Our work combines extensive numerical simulations with experimental validations to quantify the statistical uncertainties associated with the corrected event rates. We apply this methodology to the Mini-EUSO experiment onboard the International Space Station where machine learning techniques are employed to extract pixel-by-pixel double pulse resolutions from long-term photon count histograms. This integrated approach enables the accurate recovery of true photon fluxes essential for studying ELVES, meteors and other transient phenomena detected by Mini-EUSO.

We extend spontaneous baryogenesis by considering the spontaneous breaking of $U(1)_B$ through a complex vector field. This field interacts with baryons and leptons via a vector-current coupling and, by construction, acquires a nonzero vacuum expectation value. Accordingly, the theory also exhibits a spontaneous violation of Lorentz invariance, effectively realizing a Bumblebee model. In this picture, the pseudo-Nambu-Goldstone boson arising from spontaneous breaking of the $U(1)_B$ global symmetry is the global phase of the Bumblebee vector and, in the broken phase, it results minimally coupled with the baryonic current, guaranteeing the violation of the baryon number. Consequently, we assume that the pseudo-Nambu-Goldstone, arising from spontaneous breaking of $U(1)_B$, plays the role of the inflaton, leading to baryogenesis across the entire inflationary stage, up to when the inflaton decays into baryon-antilepton and antibaryon-lepton pairs through a CP-violating interaction that also violates the Lorentz symmetry. Afterwards, we address the issue of flavor oscillations among baryon and lepton fields, including the oscillation probability in the calculation of the baryon asymmetry. Remarkably, our framework predicts a non-null mixing factor even for massless fermions. This mixing acts on the spatial momenta rather than on the masses of the produced fermions, allowing larger values of the coupling constant even guaranteeing the production of light fermions. The net baryon asymmetry results accordingly modified, and may also reproduce the experimental data for allowed values of the coupling constant.

We discuss some entanglement features associated with cubic non-Gaussian perturbations in single-field inflationary scenarios. We adopt standard momentum-space techniques to show how multipartite entanglement arises for inflationary perturbation modes, focusing on the dynamics of the comoving curvature perturbation. In particular, we quantify entanglement generation via the recently proposed Entanglement Distance, which introduces a geometric interpretation of quantum correlations in terms of the Fubini-Study metric. In the continuum limit, we show that the Entanglement Distance arising from displacement transformations is proportional to the total number of excitations in the quantum state for cubic perturbations, thus providing an upper bound on the von Neumann entanglement entropy of any reduced state compatible with such excitations. Within the interaction picture, we further observe that the quantum correlations arising from cubic gravitational interactions are typically much larger than the standard squeezing contribution, in agreement with previous studies focusing on von Neumann entropy generation across the Hubble horizon. We further show how the inflationary parameters affect the total amount of such correlations, highlighting in particular their dependence on the inflationary energy scales and the number of e-foldings during slow-roll.

We explore a higher-dimensional universe that is a product of Minkowski space and the non-orientable Klein Bottle. The topology explicitly breaks important symmetries, such as translational invariance and (5+1)-dimensional CP invariance. Somewhat surprisingly, the (3+1)-dimensional cp of the Minkowski space can also be broken by the Klein Bottle, both explicitly and in the presence of a brane. The topology enforces a background of fermion correlations that amounts to a condensate wall localized in the Klein Bottle. The wall acts as an order parameter for the broken symmetries. If a brane passes through the wall, brane fermions that couple to the condensate are produced as quantified by the Bogoliubov coefficients for a time-dependent mass. The scenario meets the conditions, including cp violation, to potentially generate the matter-antimatter asymmetry of the universe.