Papers for Tuesday, Apr 01 2025

Any permutation-invariant function of data points $\vec{r}_i$ can be written in the form $\rho(\sum_i\phi(\vec{r}_i))$ for suitable functions $\rho$ and $\phi$. This form - known in the machine-learning literature as Deep Sets - also generates a map-reduce algorithm. The area of a triangle is a permutation-invariant function of the locations $\vec{r}_i$ of the three corners $1\leq i\leq 3$. We find the polynomial formula for the area of a triangle that is explicitly in Deep Sets form. This project was motivated by questions about the fundamental computational complexity of $n$-point statistics in cosmology; that said, no insights of any kind were gained from these results.

We investigate the impact of environment on quiescent galaxy (QG) size evolution using the CLAUDS+HSC imaging covering 18.6~deg$^2$ in five broad filters ($Ugriz$) and the effective radius of a single-Sérsic fit as a proxy for galaxy size. We estimate sizes in two rest-frame wavelengths -- 3000Å (UV) and 5000Å (optical) -- for $\sim86,000$ massive ($M_*>10^{9.5}$M$_\odot$) field QGs and for $1,000$ of their similarly massive counterparts from 47 clusters at $0.1<z<0.85$. We fit the size-mass relation (SMR) for field and cluster QGs in five $\Delta z=0.15$ redshift bins and use the characteristic size of $M_*=5\times10^{10}$M$_\odot$ QGs (SMR's zero point) to trace the change in galaxy size over cosmic time and in two types of environment. Sizes of QGs are larger in the rest-frame UV than in the rest-frame optical in both clusters and the field, and this difference is more prominent in the field sample. However, QGs in clusters are systematically smaller than the field QGs, and this difference is significantly more pronounced if measured in the rest-frame UV light. Modeling of the redshift evolution in the characteristic QG size as $R_e\varpropto(1+z)^{\beta}$ shows that the cluster QGs ($\beta=-1.02$ in UV and $\beta= -1.00$ in optical) grow in size as fast as the field QGs ($\beta=-0.95$ in UV and $-1.22$ in optical). This fast growth of cluster QGs is consistent with size increase driven by the accretion of two subpopulations onto clusters: a) field QGs that are larger than their quiescent counterparts in clusters, and b) environmentally quenched galaxies (newcomers) that are larger than the rest of the quiescent population.

X-rays are a critical wavelength for understanding supermassive black holes (SMBHs). X-rays probe the inner accretion flow, closest to the event horizon, where gas inspirals, releasing energy and driving black hole growth. This region also governs the launching of outflows and jets that regulate galaxy evolution and link SMBH growth to their host galaxies. This review focuses on X-ray observations of SMBHs, through "standard accretion" in persistent Active Galactic Nuclei (AGN) and in extreme transient events, such as Tidal Disruption Events (TDEs), Changing-Look AGN (CLAGN), and Quasi-Periodic Eruptions (QPEs). We describe the X-ray spectral and variability properties of AGN, and the observational techniques that probe the inner accretion flow. Through understanding the phenomenology and accretion physics in standard, individual AGN, we can better search for more exotic phenomenon, including binary SMBH mergers, or Extreme Mass Ratio Inspirals (EMRIs). In this review, the reader will discover: (1) X-ray variability on timescales from minutes to hours traces accretion near the event horizon. (2) X-rays can measure the black hole mass, spin and accretion flow geometry and dynamics. (3) In transients like TDEs, X-rays probe the newly formed accretion disk that feeds the black hole. (4) QPEs are posited to be EMRIs orbiting accreting SMBHs that would emit low-frequency gravitational waves. (5) Future X-ray, time-domain and multi-messenger surveys will revolutionize our understanding of SMBH growth.

Johannes Kepler's attempt to explain the arrangement of the six innermost planets of the Solar System using his Platonic Solid Model-which postulates that planetary orbits are nested within the five Platonic solids-was ultimately unsuccessful. However, while his model failed to describe our own planetary system, Kepler was remarkably prescient in hypothesizing the existence of exoplanetary systems that might conform to this geometric framework. In this study, we analyze all known multiple exoplanet systems containing three to six planets and identify those that best match the Keplerian Platonic model. Using a semi-major-axis (SMA) ratio metric defined as the sum of squared differences between observed and theoretical semi-major-axis ratios, we find that the most well-matched three-, four-, five-, and six-planet exoplanetary systems exhibit significantly lower discrepancy values $(4.38 \times 10^{-6}, 1.05 \times 10^{-2}, 8.21 \times 10^{-2}$, and $2.43 \times 10^{-1}$, respectively) compared to the inner six planets of the Solar System at 12.68. These results demonstrate that Kepler's Platonic Model is applicable to certain exoplanetary systems, suggesting that while the Solar System does not adhere to this idealized structure, other planetary systems may be governed by underlying geometric and mathematical principles akin to Kepler's vision. This study highlights the special nature of these exoplanetary systems and their potential alignment with the Platonic five-element framework.

This paper explores an unexpected yet compelling parallel between the evolution of the universe, as described by cosmological eras, and the artistic evolution of Taylor Swift, delineated by her distinct album eras. By mapping key characteristics and transitions in the universe's history to corresponding themes and milestones in Swift's career, I offer a novel perspective on both. I culminate with predictions for Swift's future work and dare to ask a question of cosmic importance: Could Taylor Swift's thirteenth album hold the secret to the universe's ultimate destiny?

We study line driven stellar winds using multifrequency, time-dependent radiation hydrodynamics. We compute the radiation force due to lines, the so called force multiplier, using precomputed photoionization tables and a time-dependent, local SED using a three band approximation within the hydro. We find that accounting for changes in the local SED changes the global properties of the flow. This is due to a combination of a change in the available momentum in the radiation field but also due to changes in the gas/radiation coupling mediated by the force multiplier. The acceleration can be suppressed, due to attenuation of UV flux but the force multiplier itself can be enhanced due to the overall SED hardening. We do not see evidence of a changing SED leading to formation or growth of azimuthal instabilities, as this effect appears subdominant to other instabilities in the wind. The computational methods presented can be extended to other outflow problems, notably multi-temperature disc winds and shocking in Wolf-Rayet stars.

Understanding our place in the universe is an eternal quest. Through the analysis of the 3D structures of 66 nearby open clusters using Gaia DR3 data, we discovered an intriguing pattern: most clusters show their elongation directions pointing at the Sun, suggesting that the Solar System might just be the universe's favorite spot, a cosmic feng shui hotspot! This surprising result hints at a subtle blend of geometry and geomancy.

Stellar population synthesis is a crucial methodology in astrophysics, enabling the interpretation of the integrated light of galaxies and stellar clusters. By combining empirical and/or theoretical libraries of the spectral energy distribution emitted by simple stellar populations (SSPs) with models of the star formation history (SFH) and chemical evolution, population synthesis facilitates the estimation of essential galaxy properties, such as total stellar mass, star formation rate, mass-weighted age and metallicity, etc. The Population Synthesis Toolkit (PST) is a Python library that offers a comprehensive and flexible framework for stellar population synthesis. Its main goal is to compute composite spectra using different galaxy evolution models and SSP libraries with ease and efficiency. It incorporates additional effects, such as cosmic redshift and dust extinction, and it computes several observable quantities derived from the spectra, including broadband photometric fluxes and equivalent widths.

Conventional frame-based cameras often struggle with limited dynamic range, leading to saturation and loss of detail when capturing scenes with significant brightness variations. Neuromorphic cameras, inspired by human retina, offer a solution by providing an inherently high dynamic range. This capability enables them to capture both bright and faint celestial objects without saturation effects, preserving details across a wide range of luminosities. This paper investigates the application of neuromorphic imaging technology for capturing celestial bodies across a wide range of flux levels. Its advantages are demonstrated through examples such as the bright planet Saturn with its faint moons and the bright star Sirius A alongside its faint companion, Sirius B.

Context. Protoplanetary discs are formed due to the fragmentation and collapse of giant molecular cloud cores. The physical properties and structure of a formed disc are of great importance when studying the onset of planet formation processes. Aims. Starting from the isothermal collapse of a rotating Bonnor-Ebert sphere, and assuming the conservation of angular momentum, we look for the structure equations of the newly formed protoplanetary disc. We take into account the possible role of pressure gradient in forming the initial disc structure, and compare our results with those obtained from a Keplerian infall model. Our aim is to obtain initial conditions to numerically study the evolution of the gaseous and solid components of protoplanetary discs. Methods. The structure equations developed for protoplanetary discs have been derived analytically, while these equations have been solved numerically. Results. The surface density profiles of the newly formed protoplanetary discs strongly depend on the initial rotation state of the Bonnor-Ebert sphere. According to our results, for slow rotators, gravitational instabilities can develop in the early phases of disc formation, while for relatively fast rotators, the outermost regions of the resulting discs are gravitationally stable, quite massive and highly sub-Keplerian, allowing rapid dust transport to the inner disc and subsequent planet formation.

The classical Laplace surface defines the location of circular particle orbits that do not undergo nodal precession around a planet with some obliquity. Close to the planet the surface coincides with the equator of the planet, while far from the planet it coincides with the orbital plane of the planet. We determine the shape of the Laplace surface of a circumplanetary disc that results from accretion of circumstellar gas and experiences the effects of gas pressure, self-gravity, and viscosity, as well as the gravitational effects due to the planetary spin and the star. We apply the linear theory of warped discs in the wavelike regime for a small-obliquity planet such as Jupiter. As a result of dissipation, a disc that begins slightly away from its Laplace surface will evolve to it. Because of pressure effects in typically warm circumplanetary discs, the disc is highly flattened compared with the classical Laplace surface, meaning that it is much less warped but still significantly tilted. For the case of Jupiter, the disc does not align anywhere with the equator of the planet. For such discs, the effects of self-gravity and viscosity on warping are typically small. The disc tilt is intermediate between the planet's equatorial and orbital planes. Circumplanetary discs that are much cooler than expected can undergo warping and alignment with the planet's equator at small radii. The results have implications for the orbital evolution of satellites in the solar system that are observed to be somewhat aligned with their classical Laplace surface.

We continue investigating the observed properties of the quasar 2005$+$403 seen through the highly turbulent plasma in the Cygnus region. Our earlier study Koryukova+2023 revealed a great influence of propagation effects on the observed data, e.g. numerous episodes of multiple imaging formation, angular broadening of the source size, and the detection of an extreme scattering event (ESE) in 2019, making it a good probe for thermal plasma in the interstellar medium (ISM). We report the first detection of multi-frequency and multi-epoch ESEs revealed with the RATAN-600 daily light curves of the quasar 2005$+$403. The most prominent ESE flux density modulations are found in 2011, 2015, and 2020 and each lasted about $4-5$ months. We fitted the detected ESEs jointly at 4.7/4.8, 7.7/8.2, and 11.2~GHz using the models, which allowed us to constrain the angular and linear size of the scattering lens averaged over the three ESEs $0.3\pm0.1$ mas and $0.6\pm0.1$ au, proper motion $8.3\pm0.7$ mas yr$^{-1}$ and transverse velocity $70.1\pm5.7$ km s$^{-1}$ assuming that the lens distance is 1.8 kpc, maximum free-electron density on the line of sight $1183\pm124$ cm$^{-3}$ and lens mass $(0.8\pm0.4)\times10^{-15}\,\rm M_\odot$. Using the fitting results, we reconstructed the intrinsic unscattered angular size of the quasar at the ESE epochs. We also report on the first detection of up to six ESEs in a row that occurred in the period of $2015-2016$, apparently created by multiple lenses successively crossing the line of sight.

The solver module of the Astrometric Verification Unit - Global Sphere Reconstruction (AVU-GSR) pipeline aims to find the astrometric parameters of $\sim$$10^8$ stars in the Milky Way, besides the attitude and instrumental settings of the Gaia satellite and the parametrized post Newtonian parameter $\gamma$ with a resolution of 10-100 micro-arcseconds. To perform this task, the code solves a system of linear equations with the iterative Least Squares (LSQR) algorithm, where the coefficient matrix is large (10-50 TB) and sparse and the iterations stop when convergence is reached in the least squares sense. The two matrix-by-vector products performed at each LSQR step were GPU-ported, firstly with OpenACC and then with CUDA, resulting in a $\sim$$1.5$x and $\sim$$14$x speedup, respectively, over an original code version entirely parallelized on the CPU with MPI + OpenMP. The CUDA code was further optimized and then ported with programming frameworks portable across different GPU architectures, obtaining a further $\sim$$2$x acceleration factor. One critical section of the code consists in the computation of covariances, whose total number is $N_{\rm unk} \times (N_{\rm unk} - 1)/2$ and occupy $\sim$1 EB, being $N_{\rm unk}$$\sim$$5 \times 10^8$ the total number of unknowns. This "Big Data" issue cannot be faced with standard approaches: we defined an I/O-based pipeline made of two concurrently launched jobs, where one job, i.e., the LSQR, writes the files and the second job reads them, iteratively computes the covariances and deletes them. The pipeline does not present significant bottlenecks until a number of covariances elements equal to $\sim$$8 \times 10^6$. The code currently runs in production on Leonardo CINECA infrastructure.

We present the three-dimensional kinematics of classical Cepheids (CCs) in the Small Magellanic Cloud (SMC) using Gaia DR3 data. By cross-matching the CCs obtained from the fourth phase of the Optical Gravitational Lensing Experiment with Gaia DR3, we obtain distances and proper motions (PMs) for 4,236 CCs. Among them, 91 stars with available radial velocities (RVs) enable the construction of accurate relationship between distance and RV. Furthermore, we calculate the internal PMs of the CCs, providing the internal dynamics of the SMC while removing the distance projection effects. The CCs exhibit a northeast-southwest distance gradient, with internal PMs pointing northeast for nearer stars and southwest for more distant stars, indicating a northeast-southwest elongation. The RVs of the CCs show a northwest-southeast gradient, consistent with RVs of other stellar populations and suggesting that the SMC's northwest-southeast elongation results from interactions with the Large Magellanic Cloud. The distances and RVs of the CCs are nearly uncorrelated, implying that the two elongations arise from distinct causes.

Between 2005 and 2015, the BL Lacertae object PG 1553+113 exhibited multiple very high-energy (VHE; > 100 GeV) gamma-ray flares, which were detected by the Cherenkov telescopes, High Energy Stereoscopic System (HESS), Major Atmospheric Gamma Imaging Cherenkov (MAGIC), and the Very Energetic Radiation Imaging Telescope Array System (VERITAS). Despite the uncertainty surrounding its redshift (z), various studies have sought to estimate this value. In this study, seventeen independently observed VHE gamma-ray spectra of PG 1553+113 are analyzed using four distinct extragalactic background light (EBL) models alongside the photohadronic framework. A global $\chi^2$ fit is applied to all observational data to determine the best-fitting redshift for each EBL model. Additionally, confidence level (CL) intervals for the redshift are calculated across all EBL models. The findings demonstrate that the photohadronic framework effectively describes all observed spectra. Among the EBL models, the lowest total $\chi^2$ value of 58.82 (with 58 degrees of freedom) was obtained using the model from Saldana-Lopez et al. (2021), while the highest value of 75.67 was associated with the model from Dominguez et al. (2011). The 95 per cent CL intervals for the statistical error of the redshift of PG 1553+113 are 0.500 < z < 0.537 for the Saldana-Lopez et al. (2021) model and 0.491 < z < 0.527 for the Dominguez et al. (2011) model. These results highlight the consistency of the photohadronic approach in interpreting the observed VHE gamma-ray spectra.

The high-energy particle production in the accretion flow onto black holes can be a key physics to explain the high-energy neutrino background. While the single-zone approximation has been commonly adopted in studies of the high-energy neutrino emission around black holes, the effects of the global plasma structure may be non-negligible. We carry out the first computations of cosmic-ray acceleration and high-energy neutrino emission via the hadronuclear ($pp$) interaction in global radiatively inefficient accretion flows and outflows around a supermassive black hole, using three-dimensional general relativistic magnetohydrodynamic simulation data. The Fokker-Planck equation for cosmic-ray protons is solved with a phenomenological model for the energy diffusion coefficient to express the turbulent acceleration in the sub-grid scale. The inhomogeneous and time variable structure of the accretion flow leads to a variety of particle energy distribution. The spectral energy distributions (SEDs) of neutrinos emitted from the entire region are flatter than those calculated under the single-zone approximation. In our model, the neutrino emission originating from cosmic rays advected with the outflow rather than the inflow predominates the SEDs. Such galactic nuclei can be significant sources of cosmic rays in those galaxies.

We present a novel and somewhat whimsical approach to pulsar hotspot modeling by drawing inspiration from the iconic one-eyed monster, Mike Wazowski, from \emph{Monsters, Inc.}. Utilizing X-ray high-quality timing data from NICER, we apply a Bayesian inference framework to model the X-ray pulse profile of PSR J0437--4715. Our analysis employs a \emph{Wazowski Configuration} (WC) in which the conventional hotspot parametrization is replaced with a predefined image template, whose redness and size are adjusted to mimic temperature variations. The results reveal a configuration where two hotspots--one brighter and smaller in the north represents the energetic ``University time Wazowski", and one larger yet cooler in the south represents the ``Monster, Inc. time Wazowski"--combine to produce the observed X-ray pulse profile. These findings not only demonstrate the sensitivity of pulse profile modeling to hotspot morphology but also open up the intriguing possibility that the X-ray emission of some pulsars may be interpreted as a cosmic homage to our favorite animated character.

Low surface density streams are important tracers to study the formation and evolution of the Milky Way. Using the accurate astrometric measurements from Gaia mission, we discover a low surface density stream in the north hemisphere, with length of $\sim110$ degree and width of $1.23$ kpc. The vertical velocity dispersion perpendicular to the stream is around $22.4$ km s$^{-1}$. The spectral data of member candidate stars from LAMOST and DESI shows a large metallicity range from $-1.8$ to $-0.7$. Based on those properties we claim that the stream is originated from a dwarf galaxy. The median metallicity of $\mathrm{[Fe/H]}=-1.3$ indicates a massive dwarf galaxy origination with stellar mass around $2.0\times10^7M_\odot$, which is comparable with the Fornax dwarf galaxy and smaller than LMC/SMC and Sagittarius. We also find the globular cluster Pyxis is highly associated with the stream in the phase space $E-L_Z$ and metallicity. The massive progenitor also suggests that many dwarf galaxies, including massive ones, have been disrupted during their evolution orbiting the Milky Way and left with very low surface density structures. This is important to understand the {\it missing satellites} problem. The orbit information of the stream shows tight association between its progenitor and the Vast POlar Structure (VPOS), which indicates that the satellites fell into the Milky Way in groups, which brought many globular clusters into the Milky Way.

The search for life beyond the solar system is a central goal in exoplanetary science. Exoplanet surveys are increasingly detecting potentially habitable exoplanets and large telescopes in space and on ground are aiming to detect possible biosignatures in their atmospheres. At the same time, theoretical studies are expanding the range of habitable environments beyond the conventional focus on Earth-like rocky planets and biosignatures beyond the dominant biogenic gases in the Earth's atmosphere. The present work provides an introductory compendium of key aspects of habitability and biosignatures of importance to the search for life in exoplanetary environments. Basic concepts of planetary habitability are introduced along with essential requirements for life as we know it and the various factors that affect habitability. These include the requirement for liquid water, energy sources, bioessential elements, and geophysical environmental conditions conducive for life. The factors affecting habitability include both astrophysical conditions, such as those due to the host star, as well as planetary processes, such as atmospheric escape, magnetic interactions, and geological activity. A survey of different types of habitable environments possible in exoplanetary systems is presented. The notion of a biosignature is presented along with examples of biosignatures on Earth and their applicability to habitable environments in exoplanetary systems. The desired properties of an ideal biosignature are discussed, along with considerations of the environmental context and chemical disequilibria in the assessment of biosignatures in diverse environments. A discussion of current state-of-the-art and future prospects in the search for habitable conditions and biosignatures on exoplanets is presented.

The colonization of Mars presents extraordinary challenges, including radiation exposure, low atmospheric pressure, and toxic regolith. Recent advancements in synthetic biology and genetic engineering offer unprecedented opportunities to address these obstacles by utilizing terrestrial extremophiles and engineered organisms. This paper examines the potential for creating symbiotic relationships between terrestrial microbes and hypothetical Martian life forms, should they exist, to support a sustainable human presence on Mars. Inspired by natural examples of endosymbiosis, such as mitochondria and chloroplasts, we propose methods to engineer life forms capable of enduring Martian conditions. Key components include experimental designs, laboratory simulations, and bioengineering approaches essential to this endeavor. The ethical, political, and technological challenges of introducing engineered life to Mars are critically evaluated, with an emphasis on international collaboration and robust planetary protection policies. This research underscores engineered symbiosis as a transformative strategy for enabling life to adapt and thrive on Mars while advancing humanity's aspirations for interplanetary habitation and exploration. By addressing these challenges, this work highlights a path toward sustainable life on Mars, reflecting both scientific ingenuity and ethical stewardship.

The recent evidence of nanohertz (nHz) gravitational wave (GW) background by pulsar timing array (PTA) collaborations has sparked considerable interest in understanding its astrophysical origins, particularly regarding supermassive black hole binaries (SMBHBs). In this work, we focus on individual SMBHBs that will be hopefully detected in upcoming PTA observations. The effect of nHz GWs on the pulse arriving times is in general decomposed as a pulsar term and an Earth term, where the pulsar term encodes the pulsar-Earth distance as a phase shift relative to the Earth term, but is usually treated as an extra noise source since the pulsar distance is in general not well measured with uncertainty larger than the wavelength of nHz GWs. We propose that the pulsar distance could be constrained by combining the phase information of multiple SMBHBs that are individually resolved. Using Markov chain Monte Carlo (MCMC) simulations, we demonstrate that the pulsar distances can be measured to better than $0.4$ pc (1 pc) for pulsars at $D\sim 1$ kpc ($\sim 2.2$ kpc) with 30 years of observations by a 20-pulsar PTA with a noise level of $\sigma_{\rm n}=20$ ns in the Square Kilometre Array (SKA) era.

The demographics of sub-Jovian planets around low-mass stars is dominated by populations of ``sub-Neptunes" and ``super-Earths", distinguished by the presence or absence of envelopes of low-molecular weight volatiles, i.e., H2, He, and H2O. The current paradigm is that sub-Neptunes on close-in orbits evolve into super-Earths via atmospheric escape driven by high-energy stellar irradiation. We use an integrated hydrodynamic-radiation-chemical network model of outflow to demonstrate that this escape is modulated by the abundance of H2O, an efficient infrared coolant. Increasing H2O/H2 at the base of the flow induces an order-of-magnitude decline in escape rate, with definitive consequences for retention of envelopes over Gyr. We show that saturation limits on H2O in the upper atmospheres of temperate sub-Neptunes could explain the paradoxical observations that these objects disappear more rapidly than their counterparts closer to their host stars. We also propose that the scarcity of sub-Neptunes around very low mass stars could be related to the water-poor chemistry of their antecedent protoplanetary disks. Observations of atmospheric H2O by JWST as well as searches for atmospheric escape from younger planets using H and He lines could test these predictions.

In recent astrochemical studies it has become crucial to study all the complete conformational panorama of the molecule, some of which are potentially detectable in the interstellar medium (ISM). In this context, the isomeric ratio can be used as a powerful tool to distinguish between different formation routes of molecules with increasing levels of complexity. While the most stable cis conformer of methyl formate (CH3OCHO, MF) is ubiquitous in the ISM, there is just one tentative detection of the higher-energy trans form toward the envelope of the star-forming region Sgr B2(N). Here, we present the detections of trans-methyl formate toward the Galactic Center molecular cloud G+0.693-0.027 and the protostellar shock L1157-B1, providing definite observational evidence of its presence in the ISM. Numerous unblended or slightly blended $a$-type $K_a$ = 0, 1 transitions belonging to the $A$-substate of trans-MF have been identified in both sources. We derive a molecular column density for trans-methyl formate of N = (8.2 $\pm$ 0.4) $\times$10$^{12}$ cm$^{-2}$ and N = (1.6 $\pm$ 0.3) $\times$10$^{12}$ cm$^{-2}$, respectively, yielding a molecular abundance with respect to H$_2$ of $\sim$6 $\times$ 10$^{-11}$ and $\sim$8 $\times$ 10$^{-10}$. Therefore, we obtain cis/trans isomeric ratios of $\sim$72 and $\sim$34 toward G+0.693 and L1157-B1, which are $\sim$7 and 3 times larger than that found in the Sgr B2(N) region. These results are compared with new grain-surface theoretical computations, which suggest that a stereoespecific formation of trans-MF via the CH3O + HCO route on grain surfaces can qualitatively explain the observed cis/trans abundance ratio. Nevertheless, we show that additional stereoespecific gas-phase routes could also play a crucial role in maintaining the intricate balance between formation and destruction of trans-MF, ultimately leading to its detection.

Binary neutron-star mergers offer crucial insights into the matter properties of neutron stars. We present direct evidence of phase transition on the observational signatures from such events. Our study employs a range of equations of states with hadron-quark phase transition surveying from Maxwell construction smoothened up to the Gibbs construction using a control parameter $\Delta p$. This smoothening parameter allows us to explore different mixed phases and analyse their direct impact on merger dynamics. Post-merger gravitational wave emissions reveal the expression of specific signatures in the spectogram and power spectral density, serving as a distinct signature of equations of state with mixed phases. We found additional peaks in power spectral density that were fully responsible from the post-merger remnant experiencing a phase transition. Alongside this signature, the nature of phase transition transition leaves specific imprints on the spectrogram, leading to a two-folded signature from gravitational wave analysis. Furthermore, we establish a direct correlation between our findings and the threshold mass for prompt collapse. Our analysis also provides key evidence against a Maxwell-type phase transition for GW170817 if the post-merger is believed to have experienced a prompt collapse into a black hole. We show that $\Delta p \gtrsim 0.04$ is required for such a scenario. Effects of $\Delta p$ have also been observed on the ejecta mass from the event, which can affect the kilonova afterglow.

The availability of large datasets containing stellar parameters, distances, and extinctions for stars in the Milky Way, particularly within the Galactic disk, is essential for advancing our understanding of the Galaxy's stellar populations, structure, kinematics, and chemical evolution. In this study, we present a catalog of stellar parameters, including effective temperature (\teff), metallicity (\feh), absolute magnitudes ($M_{G}$), distances ($d$), and reddening values (\ebr), for a sample of 141 million stars from the SkyMapper Southern Survey (SMSS). These parameters are derived using the SPar algorithm, which employs a fitting procedure to match multi-band photometric observations and estimate the stellar properties (\teff, \feh, $M_G$, $d$, and \ebr) on an individual star basis, following the methodology outlined in our previous work. This study successfully determines stellar parameters and extinction values simultaneously for stars located in high and low Galactic latitudes. The resulting stellar parameters and extinction values are in good agreement with results from other studies, demonstrating the robustness of our method. We derive a temperature dispersion of 195\,K and a metallicity dispersion of 0.31\,dex when comparing our results with spectroscopic data. The catalog produced in this work provides a valuable resource for future research on the Galactic metallicity distribution function, the structure of the Galaxy, three-dimensional extinction mapping, and other related astrophysical topics.

We present $BVi$ multi-band high-cadence observations of a Type II supernova (SN) KSP-SN-2022c from a star-forming galaxy at $z$ $\simeq$ 0.041 from its infant to nebular phase. Early light curve fitting with a single power-law is consistent with the first detection of roughly 15 minutes after shock breakout. The SN light curves feature a rapid rise and decline across its luminous ($V$ $\simeq$ -18.41 mag) peak together with a short plateau. The presence of the short plateau and rapid post-peak decline place the SN within a small group of transitional type between Type II-P and II-L subtypes. Its (i) broad and asymmetric H profiles with large emission-to-absorption ratios and (ii) near-peak luminosity in excess of predictions from SN shock cooling models both point to circumstellar interactions in this SN. Early colour evolution exhibits a short-lived blueward motion in $B-V$ within the first few days and continuous reddening in $V-i$, inconsistent with simple blackbody heating. Our simulations of SN light curves estimate 13 $M_\odot$ and 680 $R_\odot$ for the mass and radius of the progenitor, respectively, together with CSM of 0.73 $M_\odot$ to account for the excess luminosity and rapid post-peak declines. We discuss the origin of its short plateau and early colour evolution in the context of partial envelope stripping of the progenitor star and a delayed SN shock breakout near the edge of the CSM, respectively, as indicated by our simulations. We establish a correlation between post-peak decline rates and CSM mass in Type II SNe, highlighting that CSM interactions play a major role in shaping the post-peak evolution of transitional types.

Accurate synchrotron transfer coefficients are essential for modeling radiation processes in astrophysics. However, their current calculation methods face significant challenges. Analytical approximations of the synchrotron emissivity, absorptivity, and rotativity are limited to a few simple electron distribution functions that inadequately capture the complexity of cosmic plasmas. Numerical integrations of the transfer coefficients, on the other hand, are accurate but computationally prohibitive for large-scale simulations. In this paper, we present a new numerical method, Chorus, which evaluates the transfer coefficients by expressing any electron distribution function as a weighted sum of functions with known analytical formulas. Specifically, the Maxwell-Jüttner distribution function is employed as the basic component in the weighted sum. The Chorus leverages the additivity of transfer coefficients, drawing inspiration from an analogous approach that uses stochastic averaging to approximate the $\kappa$ distribution function. The key findings demonstrate median errors below $5\%$ for emissivity and absorptivity, with run times reduced from hours to milliseconds compared to first-principles numerical integrations. Validation against a single $\kappa$ distribution, as well as its extension to more complex distributions, confirms the robustness and versatility of the method. However, limitations are found, including increased errors at higher energies due to numerical precision constraints and challenges with rotativity calculations arising from fit function inaccuracies. Addressing these issues could further enhance the method's reliability. Our method has the potential to provide a powerful tool for radiative transfer simulations, where synchrotron emission is the main radiative process.

Cookies are enjoyed best when they are both crispy and soft. I investigate in which proportion the cookies are crispy and soft, and disentangle whether it makes them biscuits, cakes, or none of the above. I baked cookies for colleagues at KTH, Stockholm, and University of Geneva, Switzerland, adopting my mum's mum's mum's etc. recipe. I created a dedicated survey for my colleagues with three well-selected questions to answer while eating one cookie. The weighted-average mean of the crispiness and softness, weighted by the respective enjoyment of the cookie, over the whole population amount to 7.0 +/- 1.1 and 5.3 +/- 1.4, respectively. The enjoyment of the cookies amounts to 9.1 +/- 2.3. People like (my) cookies, and cookies are neither cakes, nor biscuits, they are just... cookies!

We discuss the results of the spectroscopic and photometric monitoring of the type IIn supernova (SN) 2023ldh. Survey archive data show that the SN progenitor experienced some erratic outbursts in the years before exploding. From May 2023, the source shows a general slow luminosity rise lasting over four months with some superposed luminosity fluctuations. In analogy to SN 2009ip, we label this brightening as Event A. During Event A, SN 2023ldh reaches a maximum absolute magnitude of Mr = -15.52 $\pm$ 0.24 mag. Then the light curves show a luminosity decline of about 1 mag in all filters lasting about two weeks, followed by a steep brightening (Event B) to an absolute peak magnitude of Mr = -18.53 $\pm$ 0.23 mag, replicating the evolution of SN 2009ip and similar SNe IIn. Three spectra of SN 2023ldh are obtained during Event A, showing multi-component P Cygni profiles of H I and Fe II lines. During the rise to the Event B peak, the spectrum shows a blue continuum dominated by Balmer lines in emission with Lorentzian profiles, with a full width at half-maximum (FWHM) velocity of about 650 km/s. Later, in the post-peak phase, the spectrum reddens, and broader wings appear in the H{\alpha} line profile. Metal lines are well visible with P Cygni profiles and velocities of about 2000 km/s. Beginning around three months past maximum and until very late phases, the Ca II lines become among the most prominent features, while H{\alpha} is dominated by an intermediate-width component with a boxy profile. Although SN 2023ldh mimics the evolution of other SN 2009ip-like transients, it is slightly more luminous and has a slower photometric evolution. The surprisingly homogeneous observational properties of SN 2009ip-like events may indicate similar explosion scenarios and similar progenitor parameters.

In the big data era of Astrophysics, the improvement of visualization techniques can greatly enhance the ability to identify and interpret key features in complex datasets. This aspect of data analysis will become even more relevant in the near future, with the expected growth of data volumes. With our studies, we aim to drive progress in this field and inspire further research. We present the second release of pastamarkers, a Python-based matplotlib package that we initially presented last year. In this new release we focus on big data visualization and update the content of our first release. We find that analyzing complex problems and mining large data sets becomes significantly more intuitive and engaging when using the familiar and appetizing colors of pasta sauces instead of traditional colormaps.

Generative models have recently revolutionized image generation tasks across diverse domains, including galaxy image synthesis. This study investigates the statistical learning and consistency of three generative models: light-weight-gan (a GAN-based model), Glow (a Normalizing Flow-based model), and a diffusion model based on a U-Net denoiser, all trained on non-overlapping subsets of the SDSS dataset of 64x64 grayscale images. While all models produce visually realistic images with well-preserved morphological variable distributions, we focus on their ability to learn and generalize the underlying data distribution. The diffusion model shows a transition from memorization to generalization as the dataset size increases, confirming previous findings. Smaller datasets lead to overfitting, while larger datasets enable novel sample generation, supported by the denoising process's theoretical basis. For the flow-based model, we propose an "inversion test" leveraging its bijective nature. Similarly, the GAN-based model achieves comparable morphological consistency but lacks bijectivity. We then introduce a "discriminator test", which shows successful learning for larger datasets but poorer confidence with smaller ones. Across all models, dataset sizes below O(100,000) pose challenges to learning. Along our experiments, the "two-models" framework enables robust evaluations, highlighting both the potential and limitations of these models. These findings provide valuable insights into statistical learning in generative modeling, with applications certainly extending beyond galaxy image generation.

In order to shed light on the quantum-to-classical transition of the primordial perturbations in single field inflation, we investigate the decoherence and associated quantum corrections to the correlation functions of superhorizon scalar curvature perturbations. The latter are considered as an open quantum system which undergoes quantum decoherence induced by a time-dependent environment of deep subhorizon tensorial modes through the trilinear interactions predicted by General Relativity. We first prove that, in full generality, a time dependent subhorizon environment can be relevant for decoherence during inflation, by considering derivativeless interactions, which, in our case, give the most important results. For the first time, the time dependence of the environment is properly taken into account by modifying the quantum master equation. Important non-Markovian effects pop up, instead, when dealing with derivative interactions. We adopt a possible way to treat them which has been recently proposed and seems well suited for our case. Our results show that when considering the interplay between derivativeless and derivative interactions, decoherence is slowed down. This underlines the importance of accounting for all the interactions in open quantum-system calculations in an inflationary setting. We finally compute the quantum corrections to cosmological correlation functions, by solving the transport equations induced by the quantum master equation. We also compare the results to the solutions obtained by an alternative method previously used in the literature. We observe a resummation of the quantum corrections to the power-spectrum, which is a general property of quantum master equations. We extend these results to the bispectrum, showing a decay of this correlation function in time which is analogous to the one found, previously, for the power-spectrum.

In its second data release (DR2), the \textit{Dark Energy Spectroscopic Instrument} (DESI) publicly released measurements of Baryon Acoustic Oscillations (BAO) from over 13.1 million galaxies and 1.6 million quasars, covering the redshift range $0.295 \leq z \leq 2.330$. In this work, we investigate the impact of this new dataset on dark sector interaction models, which are motivated by non-gravitational interactions between dark energy (DE) and dark matter (DM), commonly referred to as interacting dark energy models (IDE). We focus on two frameworks: the traditional IDE model and the recently proposed sign-switching Interacting model (S-IDE), aiming to derive new and robust constraints on both scenarios. After carefully selecting the sample for the joint analysis, ensuring compatibility among the data without significant tension, our main results indicate that both models can alleviate the $H_0$ tension, reducing it to moderate tension approximately $2.7\sigma$. The IDE model shows compatibility with the latest $S_8$ constraints from cosmic shear surveys, while the S-IDE model predicts lower values of $S_8$, which align with alternative perspectives on the $S_8$ tension. For the traditional IDE model, we derive new bounds for the coupling parameter, marking the strongest constraints to date through geometric measurements. This highlights the crucial role that supernova samples can play in refining these constraints. For the S-IDE model, we find mild evidence (approximately $2\sigma$) for the coupling parameter, suggesting a potential interaction between DE and DM.

Compact symmetric objects (CSOs) are a unique class of jetted active galactic nuclei (AGN) defined by sub-kpc radio emission, showing radio structure on both sides of the central engine. CSOs tend to exhibit little to no relativistic beaming, thereby allowing us to determine their physical characteristics, such as the magnetic field strength and particle energy density. Selected with a literature search, we describe VLBI observations, imaging, and analyses of 167 CSO candidates. We identified 65 new bona fide CSOs, thus almost doubling the number of known bona fide CSOs to 144. With our greater breadth of sources, we confirm that edge-dimmed CSOs (CSO-1s) may represent a more diverse population than originally expected. We highlight a number of CSOs with complex morphologies, including candidates for supermassive binary black holes (SBBHs) and CSOs that appear to have morphologies akin to wide-angle tail (WAT) galaxies, which could perhaps indicate that some CSOs are experiencing a galactic merger.

We present JWST NIRSpec spectro-imaging observations of jets from four edge-on protoplanetary disks that exhibit clear signatures of MHD disk winds. Bipolar jets are detected and spatially resolved in over 30 shock-excited forbidden lines, multiple Paschen and Brackett series lines of atomic hydrogen, and the high-energy excitation line of atomic helium (1.083 um). This helium line is the brightest jet-tracer towards HH 30 and FS TauB, which also exhibit asymmetric intensity between their red- and blue-shifted lobes in all tracers, including the [Fe II] and [He I] lines. Extinction maps reveal no significant differences across the lobes, suggesting an asymmetric jet-launching mechanism rather than environmental effects. Diagnostic line ratios yield consistent shock speeds of 50-60 km/s, jet ionization fractions of 0.1-0.2, and pre-shock electron densities of 1000 /cm^3. Combined with pixel-by-pixel electron density maps and [Fe II] line luminosities, we estimate jet mass-loss rates using three independent methods, averaging around a few 10^(-9) solar masses/yr. We estimate the accretion rates for these sources as 10 times the jet mass loss rates and find them to match well with the independently derived accretion estimates of other Class II sources in the Taurus star-forming region. Owing to JWST's high precision, we also investigate jet wiggling and find Tau 042021 to showcase the perfect case of mirror-symmetric wiggling, which can only be explained by the motion of the jet source around a stellar companion. Modeling this wiggling suggests Tau 042021 to host 0.33 and 0.07 solar masses binary at the center with binary separation of 1.35 au and an orbital period of 2.5 years.

Dark matter remains one of the most profound and unresolved mysteries in modern physics. To unravel its nature, numerous haloscope experiments have been implemented across various mass range. However, very few haloscope experiments conducted within millimeter-wave frequency range, which is in the favored mass region for well-motivated dark matter candidates. Here we designed and constructed a millimeter-wave dielectric haloscope featuring a dark matter detector composed of dielectric disks and a mirror. Using this setup, we conducted a search for dark photon dark matter and found no evidence for its existence. Our results established new constraints on the kinetic mixing parameter in the mass range from $387.72$ to $391.03$ $\mu eV$, improving the existing limits by two orders of magnitude. With future enhancements, our system has the potential to explore new parameter space for dark photon as well as axion dark matter within millimeter-wave frequency range.

Protoclusters represent the densest regions of cosmic large-scale structure in the early universe and are the environment where present-day massive elliptical galaxies are assembled. Millimeter continuum emission offers a powerful probe of obscured star formation at high redshifts across various environments. In this paper, we present deep ALMA 1.17 mm mosaic of the central 8 arcmin$^2$ ($\approx30$ comoving Mpc$^{2}$) region in the SSA22 protocluster at $z=3.09$ to study the faint dusty star-forming galaxy (DSFG) population. The continuum map achieves an RMS noise level of $\approx25$ $\mu$Jy beam$^{-1}$ at $\approx1^{\prime\prime}$ spatial resolution, $\approx2\times$ the depth of previous observation of this field. We detected 53 sources with a signal-to-noise ratio above 4.2, doubling the number of detections. Utilizing optical to mid-infrared ancillary data, we search for spectroscopic redshift and identify 18 of 53 as cluster members. For sources with more than two photometric data points in the near-infrared, stellar mass ($M_\star$) and star formation rate (SFR) from spectral energy distribution fitting are presented. The 1.17 mm number count shows $>2\times$ excess at flux density $\gtrsim1$ mJy but are consistent with blank field in fainter flux bins. The monochromatic far-infrared luminosity function of the SSA22 protocluster core region suggests a lack of faint DSFGs. All SSA22 protocluster member galaxies detected at 1.17 mm have SFR within the $M_\star$-SFR relation of general star-forming galaxies. Our results suggest that an early overdense environment like SSA22 protocluster predominantly enhances the formation of massive early-type galaxies in present-day galaxy clusters, but that the star formation in individual member galaxies is likely driven by gas supply along the cosmic web and occurs in a secular way.

The spokes observed in Saturn's rings have been a subject of scientific debate since their discovery by Stephen J. O'Meara in the 1970s and their confirmation by the Voyager flybys in the early 1980s (Smith et al., 1982). While the Cassini spacecraft confirmed that the spokes are linked to Saturn's magnetosphere, their exact formation mechanism remains uncertain. This paper proposes that the spokes in Saturn's rings consist of two distinct components: (1) carbonaceous materials, namely pyrolytic carbon with diamagnetic properties and potentially other various forms of carbon-bearing compounds, which persist over longer timescales, and (2) rapidly forming and dissipating diamagnetic ice grains, which interact with Saturn's magnetosphere on much shorter timescales. We suggest that the spokes consist of diamagnetic pyrolytic carbon that has coated silicates through the process of high-temperature Chemical Vapour Deposition (CVD) during the formation of Saturn's protoplanetary disk. Additionally, the spokes consist of diamagnetic ice particles that can disappear within minutes to hours due to sublimation. The photoelectric effect causes the pyrolytic carbon grains to lose electrons, thus becoming paramagnetic, which results in their attraction back to the main B ring structure. We suggest that Saturn's rings are charged by the solar wind, generating a magnetic field that emanates orthogonally above and below the B ring plane due to the movement of charged particles in the rings. Statistical analysis of Cassini data reveals significant correlations between spoke activity and both Saturn's magnetospheric rotation and solar elevation angle, providing strong support for an electromagnetic mechanism in spoke formation. This hypothesis suggests that the visibility of the spokes is dictated by illumination conditions and electromagnetic effects.

The spectra of coronal mass ejections (CMEs) in the low corona play a crucial role in understanding their origins and physical mechanism, and enhancing space weather forecasting. However, capturing these spectra faces significant challenges. This paper introduces a scheme of a multi-slit spectrometer design with five slits, acquiring the global spectra of the solar corona simultaneously with a focus on the spectra of CMEs in the low corona. The chosen wavelength range of the spectrometer (170-180 Å) includes four extreme ultraviolet emission lines (Fe x 174.53 Å, Fe ix 171.07 Å, Fe x 175.26 Å, Fe x 177.24 Å), which provides information of plasma velocity, density and temperature. Utilizing a numerical simulation of the global corona for both the on-disk and the off-limb scenarios, we focus on resolving the ambiguity associated with various Doppler velocity components of CMEs, particularly for a fast CME in the low corona. A new application of our decomposition technique is adopted, enabling the successful identification of multiple discrete CME velocity components. Our findings demonstrate a strong correlation between the synthetic model spectra and the inverted results, indicating the robustness of our decomposition method and its significant potential for global monitoring of the solar corona, including CMEs.

The Solar Ultraviolet Imaging Telescope (SUIT) on board the AdityaL1 mission observes the Sun in the 200-400 nm wavelength range. This paper presents the results of various on ground and on board tests and their comparison with the specifications. Moreover, we also present the scheme for data calibration. We demonstrate that the test results are compliant with the specified figures, except the spatial resolution. Such discrepancy will limit the photometric measurements only, at a scale of 2.2" instead of 1.4" as originally envisioned. The results obtained here show that SUIT observations open up a new window for solar observations.

We study the formation of the Hercules stream in the model Galactic disk which includes the outer resonance ring R1R2 located near the Outer Lindblad Resonance (OLR) of the bar. The Hercules region and the anti-Hercules region introduced for calibration were restricted in space by the solar neighborhood, r<0.5 kpc, and on the (VR, VT) plane by ellipses centered at VR=25 and VT=200 km s-1 (Hercules), and at VR=-25 and VT=200 km s-1 (anti-Hercules). The number of stars in the Hercules region reaches a maximum at the time period of 2--3 Gyr from the start of simulation and the number of stars in the anti-Hercules region oscillates with a period of 1.8 +/-0.1 Gyr. The majority of stars in the model disk located in the Hercules and anti-Hercules regions have orbits elongated perpendicular and parallel to the bar, respectively. There are two types of orbits in the Hercules region. Orbits of the first type always lie inside a figure bounded by two ellipses elongated perpendicular to the bar. Orbits of the second type are elongated at the angles of -60 or 60 degrees to the major axis of the bar most of the time. The distribution of stars in the Hercules region along the period of slow oscillations in the angular momentum has two maxima: P=0.7 and 2.6 Gyr corresponding to orbits of the first and second type. In the anti-Hercules region, most orbits are captured by libration relative to the major axis of the bar with a period of 1.9 Gyr. In general, orbits in the Hercules and anti-Hercules regions support the outer rings R1 and R2 elongated perpendicular and parallel to the bar, respectively. Stars from the Gaia DR3 catalog located in the Hercules region appear to be, on average, brighter, bluer and more luminous than stars in the anti-Hercules region which is probably caused by selection effects due to different distributions of these stellar samples over the Galactic latitude b.

We investigate the stellar populations and molecular gas properties of a star-forming region within the dwarf irregular (dIrr) galaxy WLM. Low-metallicity dIrrs like WLM offer a valuable window into star formation in environments that are unlike those of larger, metal-rich galaxies such as the Milky Way. In these conditions, carbon monoxide (CO), typically used to trace molecular clouds, is more easily photodissociated by ultraviolet (UV) radiation, leading to a larger fraction of CO-dark molecular gas, where H$_2$ exists without detectable CO emission, or CO-dark gas in the form of cold HI. Understanding the molecular gas content and the stellar populations in these star-forming regions provides important information about the role of CO-bright and CO-dark gas in forming stars.

We analyzed period changes of the high-amplitude Delta Scuti variable star CSS_J102714.3+205943 for about 20 years, utilizing data from the automated sky surveys along with our own observations. With the help of the O-C diagram, we found that the period decreased noticeably between JD2454800 and JD2457300. A possible cause of the change could be intrinsic processes in the star. However, the observed behavior of the O-C diagram can also be explained by the light-time effect if the star is a component of a binary system. Times of maxima for the star, derived from the surveys and our observations, are listed.

Context: Photometric variability is a defining characteristic of young stellar objects (YSO), which can be traced back to a range of physical processes taking place at different stages of young stars' formation and early evolution. Gaia's third Data Release (GDR3) has provided an unprecedented dataset of photometric time series, including 79375 light curves for YSO candidates. With its all-sky coverage, Gaia provides a unique opportunity for large-scale studies of YSO variability. Aims: Our goal was to characterise the GDR3 sample of YSO variables further and verify the recurrence of YSO variability modes due to accretion, extinction, rotation modulation, etc. By adapting the Q&M methodology for Gaia's sparse and long-term light curves, we seek to bridge the gap between low and high-cadence surveys' insights on YSO variability. Methods: We piloted the application of the asymmetry (M) and periodicity (Q) variability metrics to characterise YSO variability with Gaia light curves. Through refined sample selection, we identified sources with appropriate sampling for the Q&M methodology. We used the Generalised Lomb Scargle periodogram and structure functions to infer variability timescales. Results: We successfully derived Q&M indices for ~23000 sources in the GDR3 YSO sample. These variables were then classified into eight variability morphological classes. We linked morphological classes with physical mechanisms by using H$\alpha$ as a proxy of accretion and $\alpha_\mathrm{IR}$-indices to gauge circumstellar material's presence. Conclusions: We demonstrate that the Q&M metrics can be successfully applied to Gaia's sparse time-series. We applied them to distinguish between the several variability modes. While our results are generally consistent with previous high-cadence, short-term studies, we find that GDR3's long timespan yields an enhanced variety of variability mechanisms.

It has been shown that proton ingestion episodes can happen in the formation of hot-subdwarf stars, and that neutron-capture processes are possible in those cases. Moreover, some helium-rich hot subdwarfs display extraordinarily high abundances of heavy elements such as Zr, Yr and Pb on their surfaces. We explore under which conditions neutron-capture processes can occur in late helium core flashes, i.e. those occurring in the cores of stripped red-giant stars. We compute evolutionary models through the helium core flash and the subsequent hydrogen ingestion episode in stripped red giant stars. Stellar structure models are then used in post-processing to compute the detailed evolution of neutron-capture elements. We find that for metallicities of $10^{-3}$ and below, neutron densities can be as high as $10^{15}\,$cm$^{-3}$ and intermediate neutron capture processes occur in some of our models. The results depend very strongly on the H-envelope mass that survives after the stripping. Interestingly, we find that computed abundances in some of our models closely match the element abundances up to tin observed for EC 22536-5304, the only well-studied star for which the hot-flasher scenario assumed in our models is the most likely evolutionary path. Intermediate neutron capture processes can occur in the He-core flash experienced by the cores of some stripped red giants, and might be connected to the abundances of heavy elements observed in some helium-rich hot-subdwarf stars. The agreement between the observed abundances in EC 22536-5304 and those of our models offers support to our nucleosynthesis calculations. Moreover, if confirmed, the idea that heavy element abundances retain signatures of the different evolutionary channels opens the possibility that heavy element abundances in iHe-sdOB stars can be used to infer their evolutionary origin.

Solar Cycle (SC) 24 was the weakest in the space age, yet it produced many sustained gamma ray emission (SGRE) events from the Sun. Solar cycle (SC) 25, which is a bit stronger than SC 24 observed only a handful of SGRE events over the first five years. Here we report on the 2024 September 14 SGRE event, which has the longest duration (\~11.29 hrs) as of this writing. The associated type II radio burst is also of long duration (\~16 hr). Detailed analysis of the SGRE event reveals that the event is in good agreement with the linear relation of the SGRE duration with the ending frequency and duration of the type II burst. The kinematics of the associated coronal mass ejection (CME) shows that it is one of the fastest CMEs of SC 25, capable of driving a shock that accelerated >300 MeV protons to account for the observed SGRE. By comparing with an event with similar durations in SC 24, we find that it had a lower-speed CME but resulted in a larger-sized SGRE event. We speculate that the difference may be due to the change in the heliospheric state between the two cycles.

Catsteroseismology, or asterocatsmology, is an unexplored area of observational and theoretical research that proposes to use purr-mode oscillations to study the much-beloved but poorly-understood species Felis catus. In this work, we conduct a survey to measure fundamental purrameters of cats and relate them to their purr-modes. Relations between these fundamental cat purrameters, which include physical (eg. size, cuddliness) and personality (eg. aggression, intelligence) traits, and purr-modes can help probe their inner lives and emotions. We find that while purr characteristics tentatively trend with several physical and personality traits, more data is required to better constrain these relationships and infer the direct predictive power of personality on purr-modes, or vice versa.

We present a comprehensive analysis of AstroSat/LAXPC data of the second spin-up and second spin-down phases of the persistent X-ray pulsar 4U 1626-67. Flares followed by a broad dip are detected in the spin-up observations. The pulse profiles changed from a shoulder-like structure to a broad sinusoidal shape as the source underwent a torque reversal from spin-up to spin-down. Energy-resolved pulse profiles in lower energies showed a double-horned profile in the spin-up state and a flat top with multiple peaks in the spin-down state. Regardless of the torque state, the pulse profiles exhibit a broad single-peaked shape at higher energies. The observation in the spin-down era is characterised by the presence of a prominent QPO at 46.5 +/- 1.0 mHz frequency. The QPO rms and centre frequency show a correlation with energy. Spin-up and spin-down states show a difference in the shape of the power density spectrum. After the torque reversal, a gradual flux drop and the hardening of the spectra were observed. The difference in the shape of the pulse profiles and the presence and absence of QPOs can be explained by the change in accretion flow geometry of the pulsar, from pencil-beam to fan-beam, between spin-down and spin-up states.

We report on the observation of first, second, and third harmonic components during an interplanetary (IP) type II solar radio burst observed on 2024 September 14 by the radio instruments on board Wind, the Solar Terrestrial Relations Observatory (STEREO), and the Parker Solar Probe. The eruption resulted in an ultrafast coronal mass ejection (CME) that had a sky plane speed of \~2366 km per sec, and an X4.5 flare from NOAA active region 13825 (S15E56). Also observed were a large solar energetic particle (SEP) event and a sustained gamma ray emission (SGRE) event. The IP type II burst consists of multiple features. The first, second, and third harmonic bursts are smooth and diffuse with additional patchy bursts superposed only on the fundamental component. The existence of fundamental harmonic structure including the third harmonic can be readily explained by the coherent plasma emission mechanism and works against the possibility of synchrotron mechanism.

Galaxy cluster X-ray cavities are inflated by relativistic jets that are ejected into the intracluster medium by active galactic nuclei (AGN). AGN jets prevent predicted cooling flow establishment at the cluster centre, and while this process is not well understood in existing studies, simulations have shown that the heating mechanism will depend on the type of gas that fills the cavities. Thermal and non-thermal distributions of electrons will produce different cavity Sunyaev Zel'dovich (SZ) effect signals, quantified by the 'suppression factor' f. This paper explores potential enhancements to prior constraints on the cavity gas type by simulating suppression factor observations with the Square Kilometre Array (SKA). Cluster cavities across different redshifts are observed to predict the optimum way of measuring f in future observations. We find that the SKA can constrain the suppression factor in the cavities of cluster MS 0735.6+7421 (MS0735) in as little as 4 h, with a smallest observable value of f~0.42. Additionally, while the SKA may distinguish between possible thermal or non-thermal suppression factor values within the cavities of MS0735 if it observes for more than 8 h, determining the gas type of other clusters will likely require observations at multiple frequencies. The effect of cavity line of sight (LOS) position is also studied, and degeneracies between LOS position and the measured value of f are found. Finally, we find that for small cavities (radius < 80 kpc) at high redshift (z~1.5), the proposed high frequencies of the SKA (23.75-37.5 GHz) will be optimal, and that including MeerKAT antennas will improve all observations of this type.

Radio galaxies (RGs) are a subclass of active galactic nuclei, which are suggested to be the parent populations of blazars. According to the accretion-ejection paragram, RGs can be classified into low-excitation or high-excitation radio galaxies (LERGs or HERGs). In this paper, we compiled a distance-limited ($z<0.15$) sample of 431 LERGs (Fanaroff-Riley, or FR, type 0, I, and II RGs) to discuss their jet formation mechanism with the ADAF (advection-dominated accretion flow) scenario, and compare their accretion properties with Fermi BL Lacertae objects. We explored different jet mechanisms (Blandford-Znajek [BZ] model and a mixture of the BZ and Blandford-Payne, hybrid, model) within the framework of ADAF-type disc around a Kerr black hole for both LERGs and Fermi BL Lacs. Based on standard assumptions on the accretion-ejection coupling in RGs, the maximum kinetic jet and accretion power for FR 0s, FR Is, FR IIs can be, explained by an ADAF with the pure BZ mechanism or hybrid jet mechanism. In addition, for one third of the FR IIs, to account for their higher kinetic jet power than what is simply expected by the hybrid jet mechanism, the magnetic field could play an important role as in the form of magnetization-driven outflows or stronger magnetic structures, as observed in some BL Lacs with high jet powers. Similarities between BL Lacs and LERGs (e.g., accretion-ejection and clustering properties) suggest that high synchrotron peaked BL Lacs could be the beamed counterparts of FR 0s, and a potential general unification between LERGs and BL Lacs populations is discussed. However, a complete sample of BL Lacs is needed to robustly compare the jet and accretion properties with those of LERGs in the future.

Magnetic fields are an important component of the interstellar medium (ISM) of galaxies. The thermal gas in the ISM has a multiphase structure, broadly divided into ionised, atomic, and molecular phases. The connection between the multiphase ISM gas and magnetic field is not known and this makes it difficult to account for their impact on star formation and galaxy evolution. Usually, in star formation studies, a relationship between the gas density, $n$ and magnetic field strength, $B$, is assumed to study magnetic fields' impact. However, this requires the knowledge of the geometry of star-forming regions and ambient magnetic field orientation. Here, we use the Zeeman magnetic field measurements from the literature for the atomic and molecular ISM and supplement the magnetic field estimates in the ionised ISM using pulsar observations to find a relation between the turbulent kinetic, $E_{\rm kin}$, and magnetic, $E_{\rm mag}$, energy densities. Across all three phases and over a large range of densities ($10^{-3}\,{\rm cm}^{-3} \lesssim n \lesssim 10^{7}\,{\rm cm}^{-3}$), we find $E_{\rm mag} \propto E_{\rm kin}$. Furthermore, we use phase-wise probability density functions of density, magnetic fields, and turbulent velocities to show that the magnetic field fluctuations are controlled by both density and turbulent velocity fluctuations. This work demonstrates that a combination of both the density and turbulent velocity determines magnetic fields in the ISM.

Supernova remnants (SNRs) provide crucial information of yet poorly understood mechanism of supernova explosion. Here we present XRISM high-resolution spectroscopy of the intermediate-mass-element (IME) ejecta in the SNR Cas A to determine their velocity distribution and thermal properties. The XRISM/Resolve spectrum in the 1.75-2.95 keV band extracted from each $1' \times 1'$ region in the southeast and northwest rims is fitted with a model consisting of two-component plasmas in non-equilibrium ionization with different radial velocities and ionization timescales. It is found that the more highly ionized component has a larger radial velocity, suggesting that this component is distributed in the outer layer and thus has been heated by the SNR reverse shock earlier. We also perform proper motion measurement of the highly ionized component (represented by the Si XIV Ly$\alpha$ emission), using archival Chandra data, to reconstruct the three-dimensional velocity of the outermost IME ejecta. The pre-shock (free expansion) velocity of these ejecta is estimated to range from 2400 to 7100 km s$^{-1}$, based on the thermal properties and the bulk velocity of the shocked ejecta. These velocities are consistent with theoretical predictions for a Type IIb supernova, in which the progenitor's hydrogen envelope is largely stripped before the explosion. Furthermore, we find a substantial asymmetry in the distribution of the free expansion velocities, with the highest value toward the direction opposite to the proper motion of the neutron star (NS). This indicates the physical association between the asymmetric supernova explosion and NS kick.

Second-generation circumbinary discs around evolved binary stars, such as post-Asymptotic Giant Branch (post-AGB) stars, provide insights into poorly understood mechanisms of dust processing and disc evolution across diverse stellar environments. We present a multi-wavelength polarimetric survey of five evolved binary systems - AR Pup, HR 4049, HR 4226, U Mon, and V709 Car - using the SPHERE/ZIMPOL instrument. Post-AGB discs show significant polarimetric brightness at optical and near-IR wavelengths, often exceeding 1% of the system's total intensity. We also measured a maximum fractional polarization of the scattered light for AR Pup of ~0.7 in the V-band and ~0.55 in the I-band. To investigate wavelength-dependent polarization, we combine the SPHERE/ZIMPOL dataset with results from previous SPHERE/IRDIS studies. This analysis reveals that post-AGB discs exhibit a grey to blue polarimetric colour in the optical and near-IR. Along with high fractional polarization and polarized intensity distribution, these findings indicate that porous dust aggregates dominate the surface dust composition. We also find evidence of diverse disc geometries within the post-AGB sample, including arcs, asymmetries and variations in disc size across optical and near-IR wavelengths for some systems. Combining our findings with existing multi-technique studies, we question the classification of two systems in our sample, HR 4226 and V709 Car, which were originally identified as post-AGB binaries based on their near-IR excess. On comparing post-AGB discs to circumstellar environments around AGB stars and YSOs, we found that post-AGB systems exhibit a higher degree of polarization than single AGB stars and are comparable to the brightest protoplanetary discs around YSOs. Overall, our results reinforce the importance of polarimetric observations in probing dust properties and complex circumbinary structures.

It was previously believed that, the long-term persistent increase in the spin-down rate of the Crab pulsar following a glitch is direct evidence of a starquake-induced glitch or at least related to a starquake. Using radio data covering 1710 days following the 2017 glitch, we obtain an extreme persistent increase of the spin-down rate, which allows to test two prevailing models related to starquake through an interrelation analysis between glitch size (the amplitude of the frequency step at a glitch) and persistent increase in the spin-down rate of the star. Our results do not support the hypothesis that glitches induce the external torque variation of the Crab pulsar, which may indicate no occurrence of starquake during the Crab pulsar glitch. This can explain why no changes in the radio and X-ray flux, pulse profile and spectrum of the Crab pulsar have been observed. We also suggest an internal mechanism due to superfluidity as an explanation for the long-term persistent shift in spin-down rate of the Crab pulsar following the relatively large glitches.

The Milky Way's Central Molecular Zone (CMZ) is measured to form stars 10 times less efficiently than in the Galactic disk, based on emission from high-mass stars. However, the CMZ's low-mass protostellar population, which accounts for most of the initial stellar mass budget and star formation rate (SFR), is poorly constrained observationally due to limited sensitivity and resolution. We present the Dual-band Unified Exploration of Three CMZ Clouds (DUET) survey, targeting the 20 km/s Cloud, Sgr C, and Dust Ridge cloud e using the Atacama Large Millimeter/submillimeter Array (ALMA) at 1.3 and 3 mm. The mosaicked observations achieve a comparable resolution of 0.2-0.3" (~1600-2500 au) and a sky coverage of 8.3-10.4 square arcmin, respectively. We report 563 continuum sources at 1.3 mm and 330 at 3 mm, respectively, and a dual-band catalog with 450 continuum sources. These sources are marginally resolved at the 2,000 au resolution. We find a cloud-wide deviation (>70%) from commonly-used dust modified blackbody (MBB) models, characterized by either low spectral indices or low brightness temperatures. Three possible explanations for the deviation are discussed. (1) Optically thick Class 0/I Young stellar objects (YSOs) with very small beam filling factors can lead to lower brightness temperatures than what MBB models predict. (2) Large (mm/cm-sized) dust grains have more significant self-scattering, and therefore frequency-dependent albedo could cause lower spectral indices. (3) Free-free emission over 30 uJy can severely contaminate dust emission and cause low spectral indices for mJy sources in our sample, although the needed number of massive protostars (embedded UCHII regions) is infeasibly high for the normal stellar initial mass function. A reliable measurement of the SFR at low protostellar masses will require future work to distinguish between these possible explanations.

We present a statistical study on the formation and growth of black holes (BHs) seeded by gravothermal core-collapse of self-interacting dark matter (SIDM) halos at high redshifts, using a semi-analytical framework based on Monte-Carlo merger trees. We demonstrate that BH formation via gravothermal collapse naturally occurs in high-concentration halos at a characteristic mass scale determined by the SIDM cross section, and only during the early Universe. This mechanism is particularly promising for explaining the abundance of little red dots (LRDs) -- a population of early, apparently galaxy-less active galactic nuclei hosting supermassive BHs. By incorporating this seeding process with simplified models of BH growth and mergers, we successfully reproduce the observed LRD mass function for moderately large cross sections of $\sigma_{0m} \sim 30 \mathrm{cm^2\,g^{-1}}$ and $\omega \sim 80\,\mathrm{km\,s^{-1}}$, intriguingly consistent with independent local constraints derived from galaxy rotation curves. Our results highlight the potential of high-redshift BH statistics as a complementary probe for constraining SIDM models.

The remnant black hole-accretion disk system resulting from binary neutron star mergers has proven to be a promising site for synthesizing the heaviest elements via rapid neutron capture (r-process). A critical factor in determining the full r-process pattern in these environments is the neutron richness of the ejecta, which is strongly influenced by neutrino interactions. One key ingredient shaping these interactions is fast neutrino flavor conversions (FFCs), which arise due to angular crossings in neutrino distributions and occur on nanosecond timescales. We present the first three-dimensional, in-situ, angle-dependent modeling of FFCs in post-merger disks, implemented within general relativistic magnetohydrodynamics with Monte Carlo neutrino transport. Our results reveal that, by suppressing electron neutrinos, FFCs more efficiently cool the disk and weaken the early thermally driven wind. Less re-leptonization due to electron neutrino absorption makes this cooler wind more neutron-rich, producing a more robust r-process at higher latitudes of the outflow. This study underscores the necessity of incorporating FFCs in realistic simulations.

We report the detection of whisky in the atmosphere of the extrasolar super-Earth planet GJ 1132b from transmission spectroscopic data. It is seen both in atmospheric absorption as well as in chromospheric emission, the latter probably due to the intense heating of the co-rotating planet's day-side surface. This detection cannot be explained using natural sources of alcohol, implying that there must be a technically advanced civilisation -- possibly originating from the neighboring habitable planet GJ 1132c -- that is engaged in massive distilling operations accompanied by high levels of industrial pollution. The reason for the necessarily vast scale of production is either to produce rocket fuel for an interplanetary economy or, more likely, for an unusually high level of personal consumption. The latter hypothesis suggests a novel explanation for the Fermi Paradox (the lack of indirect or direct contact with extraterrestrials): a technically versed civilisation would be incapable of achieving the higher technical levels necessary for the development of a detectable radio signature -- much less interstellar travel -- at the suggested rates of consumption.

We present high-angular resolution (0.068", ~400pc) ALMA imaging of the [CII] line and dust continuum emission of PSO J352.4034-15.3373, a radio-loud quasar at z=5.83. The observations reveal a remarkably close match between the orientation of the [CII] and thermal dust emission mapped by ALMA, and radio synchrotron emission of a radio jet previously mapped by the VLBA. This narrow alignment extends over ~4kpc, reminiscent of the well-studied 'alignment effect' in lower-redshift radio galaxies. The [CII] kinematics show a linear increase in velocity with galactocentric radii up to ~200 km/s at r=2kpc, consistent with bulk motions within the galaxy potential, and not relativistic jet motions. The kinematics and respective morphologies are consistent with a picture in which the relativistic jet injects energy into the interstellar medium (potentially leading to subsequent star formation), giving rise to the observed alignment and significant (> 100 km/s) [CII] velocity dispersion within the host galaxy on kiloparsec scales. Indeed, the astonishingly close alignment and narrow linearity of the radio jet with the [CII] and dust emission are hard to conceive without some fundamental relationship between the two.

Investigations of the Galactic black hole low-mass X-ray binaries (BH-LMXBs) offer valuable insights into the elusive black hole population in the Milky Way. Motivated by recent tensions in the natal kick velocity distribution and BH mass distribution of BH-LMXBs, we revisit the spatial distribution of the Galactic BH-LMXBs using a new set of distance measurements obtained from an X-ray spectral modelling framework that we introduced in earlier work. We perform a multiparameter simulation study to mitigate part of the bias present in our prior estimates and gain insights into possible observational selection effects that affect the observed population. We derive a bias correction factor, well described by a Pareto probability density function that closely follows an inverse-square law dependence on distance. We then construct a bias-corrected, literature-independent, Galactic spatial distribution that clearly traces spiral arm structures and shows a deficit of sources very close to the Galactic centre, which might be explained due to high extinction or a true paucity of these sources at that region. Further analysis of the simulation results provides hints for a hidden population of BH-LMXBs at low Galactic heights. Lastly, we estimate the root-mean-squared Galactic height and find that it is most compatible with a hybrid scenario of BH formation, with some BHs receiving high natal kicks and thus propelled further from the thin disc plane while others receiving low natal kicks and remaining close to their birth place.

Observation of multifrequency angular power spectrum of the redshifted 21-cm brightness temperature fluctuation from the neutral hydrogen holds the key to understand the structure formation and its evolution during the reionization and post-reionization era. A major challenge in observing the neutral hydrogen arises from presence of strong foreground signals in the frequency range of interest. Mitigating the direct effect of foregrounds are being addressed through various techniques in literature. An additional second order effect arises, in presence of foreground, with limited accuracy in time and frequency dependent gain calibrations. This manifests as the residual gain and bandpass error in the observed data, introduces bias and increases uncertainty in the estimates of multifrequency angular power spectrum. In this work, we present an analytic method to estimate the bias and excess uncertainty in the estimates of multifrequency angular power spectrum in presence of residual gain and bandpass errors. We use this framework to estimate the effect of these errors for detection of redshifted 21-cm emission from a redshift of $\sim 8$ with the upcoming SKA1-Low. Due to the high baseline density at the required range of angular multipoles, the SKA1-Low is found to be a tuned instrument for the redshifted 21-cm signal detection. We find that, there are scenario with residual gain and bandpass errors where there can be significant bias in these estimates. Certain foreground mitigation strategies, is expected to reduce a part of the bias. The detailed study of different aspects of gain and bandpass errors and their relative effects are discussed. We find, with assumed models of gain and bandpass errors, signal detection is possible at this redshift with $128$ hours of observations. However, to achieve this one needs to have better calibration accuracy than present day interferometers.

A program to search for radio emission from dwarf-novae-type cataclysmic variables was conducted with the South African MeerKAT radio telescope. The dwarf novae RU Pegasi, V426 Ophiuchi and IP Pegasi were detected during outburst at L-band (1284 MHz central frequency). Previously, only one cataclysmic variable was radio-detected at a frequency this low. We now bring the number to four. With these three newly found radio-emitters, the population of dwarf novae confirmed to be radio-emitting at any frequency reaches 10 systems. We found that the radio luminosity is correlated with the optical luminosity. For V426 Ophiuchi and RU Pegasi we found a radio decline contemporary with the outburst's optical decline. The peak radio luminosity of dwarf novae in outburst is very similar to that of novalike Cataclysmic Variables and no correlation with orbital period is seen.

The molecule 1,3-butadiene (CH2CHCHCH2) could play a key role in the synthesis of the cyclic molecules cyclopentadiene and benzene in cold dense clouds. Since 1,3-butadiene is non-polar, we searched for its cyano derivative, which exists in the form of three different polar isomers, in the cold dense cloud TMC-1. We used the most recent data obtained with the Yebes 40m telescope in the Q band (31.0-50.3 GHz) in the frame of the QUIJOTE project. We do not detect any of the two isomers of 1-cyano-1,3-butadiene, and derive 3sigma upper limits to their column densities of 1.2e10 cm-2 and 2.0e10 cm-2 for E- and Z-1-cyano-1,3-butadiene, respectively. Our results are not consistent with those from Cooke et al. (2023), who determine a column density of 3.8e10 cm-2 for E-1-cyano-1,3-butadiene in TMC-1 using GBT data and a line stack technique. At the current level of sensitivity of our data, there is tentative evidence for the presence of the third cyano derivative isomer, 2-cyano-1,3-butadiene, although a firm detection must await more sensitive data. We derive an upper limit to its column density of 3.1e10 cm-2. This isomer cannot be formed in the reaction between CN and 1,3-butadiene, according to experimental and theoretical studies, and thus we speculate whether it could arise from neutral-neutral reactions like C2H3 + CH2CHCN and CH2CCN + C2H4. From the upper limit on the abundance of 1-cyano-1,3-butadiene derived here, we estimate that the abundance of 1,3-butadiene in TMC-1 is below 1e-11 - 1e-10 relative to H2. The low abundance inferred for 1,3-butadiene makes it unlikely that it plays an important role in bottom-up routes to cyclopentadiene and benzene.

In this contribution we give a brief account of the problem of the Global Astrometric Sphere Reconstruction in Astrometry, with particular reference to the Gaia and Gaia-like astrometric missions, namely those adopting a scanning strategy with observations in TDI mode. We sketch the design of the Gaia mission, the mathematical modelling that comes naturally from its observing strategy, and how the problem of the global sphere reconstruction translates into that of the solution of large, sparse, and overdetermined system of linearized equations. After a short description of the two approaches to this problem implemented in the Gaia data reduction pipelines, we list the main known problems of the current approaches, with specific reference to the calibration and the correlation issues. Finally, we suggest how an arc-based solution could help to alleviate some of these problems, how it would be possible to devise a mathematical model for such an observable despite the TDI observing mode, and the main difficulty that a parallel implementation of this model would have to solve.

Narrow-line Seyfert 1 AGNs (NLS1s) represent a unique stage in the black hole growth history, characterised by low black hole masses of approximately $10^{6}$-$10^{8}$ solar masses and around-Eddington accretion rates. X-ray studies of NLS1s have largely been confined to the local Universe ($z < 0.2$), while their broad-line counterparts and radio-loud quasars have been more extensively investigated at higher redshifts. In this work, we conducted an X-ray spectral analysis for 14 SDSS-observed NLS1s at $z\approx1$ in the eRASS1 catalogue. We found that all of their eROSITA observations agree with the expected rest-frame 2 keV monochromatic luminosity given their rest-frame 2500 angstrom monochromatic luminosity, further supporting evidence of AGN emission. Second, when fitted with a power-law model, most continuum spectra between 0.7-7 keV in their rest frames necessitate photon indices $\Gamma\gtrsim2.5$. Notably, the highest photon index of around 4.7 in one of our NLS1 AGNs hints at a significant contribution from soft excess emission. Finally, our analysis demonstrates that we can align the Eddington ratios with optical measurements by applying a correction factor between 10-120 to their X-ray luminosity. Although measurement uncertainty remains considerable, our findings suggest that assumptions for the standard geometrically thin accretion disc model made in previous estimations of this correction factor may not apply to near or super-Eddington NLS1 AGNs. Finally, we also compare this sample with extremely variable nearby NLS1s and other X-ray-weak AGNs, such as JWST-observed, broad-line AGNs at $z=5-6$, and underscores the importance of deeper X-ray surveys for more X-ray-weak NLS1s.

We report on the 2024 September 9 sustained gamma ray emission (SGRE) event observed by the Large Area Telescope onboard the Fermi satellite. The event was associated with a backside solar eruption observed by multiple spacecraft such as the Solar and Heliospheric Observatory (SOHO), Solar Terrestrial Relations Observatory (STEREO), Parker Solar Probe (PSP), Solar Orbiter (SolO), Solar Dynamics Observatory (SDO), Wind, and GOES, and by ground based radio telescopes. SolO Spectrometer Telescope for Imaging X rays (STIX) imaged an intense flare, which occurred about 41 deg behind the east limb, from heliographic coordinates S13E131. Forward modeling of the CME flux rope revealed that it impulsively accelerated (3.54 km s^{-2}) to attain a peak speed of 2162 km s^{-1}. SolO energetic particle detectors (EPD) observed protons up to about 1 GeV from the extended shock and electrons that produced a complex type II burst and possibly type III bursts. The durations of SGRE and type II burst are consistent with the linear relation between these quantities obtained from longer duration (exceeding 3 hours) SGRE events. All these observations are consistent with an extended shock surrounding the CME flux rope, which is the likely source of high energy protons required for the SGRE event. We compare this event with six other BTL SGRE eruptions and find that they are all consistent with energetic shock driving CMEs. We also find a significant east west asymmetry in the BTL source locations.

Massive stars undergoing iron core collapse at the end of their evolution terminate their lives either in successful or failed supernovae (SNe). The physics of core collapse supernovae (CCSNe) is complex, and their understanding requires computationally expensive simulations. The sampling of large, densely sampled parameter spaces of SN progenitors, as is needed e.g. for population synthesis studies, is thus not feasible. To remedy this situation, we present criteria that allow us to predict the final fates of stars by evaluating multiple explodability proxies derived from the stellar structure at the onset of core collapse. These are formulated based on the outcomes of a semi-analytic supernova model, evaluated over a set of ~3,900 heterogeneous stellar progenitors (single stars, binary-stripped and accretor stars). Over these, the explodabiliy criteria achieve an accuracy of >99% agreement with the semi-analytic model. The criteria are tested on 29 state-of-the-art 3D CCSN simulation outcomes from two different groups. Furthermore, we find that all explodability proxies needed for our pre-SN criteria have two distinct peaks and intervening valleys as a function of the carbon-oxygen (CO) core mass $M_\mathrm{CO}$, which coincide with failed and successful SNe, respectively. The CO core masses of explodability peaks shift systematically with metallicity, $Z$, and with the timing of hydrogen-rich envelope removal in binary-stripped stars. With these, we identify critical values in $M_\mathrm{CO}$ that define windows over which black holes form by direct collapse. The outcome is a CCSN recipe based on $M_\mathrm{CO}$ and $Z$, applicable for rapid binary population synthesis and other studies. Our explodability formalism is consistent with SN observations that constrain the progenitor $M_\mathrm{CO}$ and partially addresses the missing red supergiant problem by direct black hole formation.

The advent of next-generation radio telescopes is set to transform radio astronomy by producing massive data volumes that challenge traditional processing methods. Deep learning techniques have shown strong potential in automating radio analysis tasks, yet are often constrained by the limited availability of large annotated datasets. Recent progress in self-supervised learning has led to foundational radio vision models, but adapting them for new tasks typically requires coding expertise, limiting their accessibility to a broader astronomical community. Text-based AI interfaces offer a promising alternative by enabling task-specific queries and example-driven learning. In this context, Large Language Models (LLMs), with their remarkable zero-shot capabilities, are increasingly used in scientific domains. However, deploying large-scale models remains resource-intensive, and there is a growing demand for AI systems that can reason over both visual and textual data in astronomical analysis. This study explores small-scale Vision-Language Models (VLMs) as AI assistants for radio astronomy, combining LLM capabilities with vision transformers. We fine-tuned the LLaVA VLM on a dataset of 59k radio images from multiple surveys, enriched with 38k image-caption pairs from the literature. The fine-tuned models show clear improvements over base models in radio-specific tasks, achieving ~30% F1-score gains in extended source detection, but they underperform pure vision models and exhibit ~20% drop on general multimodal tasks. Inclusion of caption data and LoRA fine-tuning enhances instruction-following and helps recover ~10% accuracy on standard benchmarks. This work lays the foundation for future advancements in radio VLMs, highlighting their potential and limitations, such as the need for better multimodal alignment, higher-quality datasets, and mitigation of catastrophic forgetting.

We use the framework of microlensing to show that observations of binary systems, such as those made by {\it Gaia}, combined with follow-up weak lensing measurements, can provide a means to probe halos of exotic matter, possibly clumped around compact objects such as black holes. This could potentially cover a broad range of physical scenarios - from dark matter mini-halos to black holes with bosonic configurations around them, known as hair. Assuming that light can freely propagate through the halo of the exotic matter, the companion star will produce characteristic, sizable lensing signatures due to the deviation from a central gravitational potential. The signature of the multiple images, the magnification and the light-curve could be the smoking gun of such structures. We discuss how the precise observations of the {\it Gaia} survey offer an opportunity to search for new, yet undiscovered fundamental fields interacting gravitationally with baryons.

Context. The majority of massive stars are born with a close binary companion. How this affects their evolution and fate is still largely uncertain, especially at low metallicity. Aims. We derive synthetic populations of massive post-interaction binary products and compare them with corresponding observed populations in the Small Magellanic Cloud (SMC). Methods. We analyse 53298 detailed binary evolutionary models computed with MESA. Our models include the physics of rotation, mass and angular momentum transfer, magnetic internal angular momentum transport, and tidal spin-orbit coupling. They cover initial primary masses of 5-100Msun, initial mass ratios of 0.3-0.95, and all initial periods for which interaction is expected. They are evolved through the first mass transfer and the donor star death, a possible ensuing Be/X-ray binary phase, and they end when the mass gainer leaves the main sequence. this http URL our fiducial synthetic population, 8% of the OB stars in the SMC are post-mass transfer systems, and 7% are merger products. In many of our models, the mass gainers are spun up and form Oe/Be stars. While our model underpredicts the number of Be/X-ray binaries in the SMC, it reproduces the main features of their orbital period distribution and the observed number of SMC binary WR stars. We expect $\sim$50 OB+BH binaries below and $\sim$170 above 20d orbital period. The latter might produce merging double BHs. However, their progenitors, the predicted long-period WR+OB binaries, are not observed. Conclusions. While the comparison with the observed SMC stars supports many physics assumptions in our high-mass binary models, a better match of the large number of observed OBe stars and Be/X-ray binaries likely requires a lower merger rate and/or a higher mass transfer efficiency during the first mass transfer. The fate of the initially wide O star binaries remains uncertain.

Massive star evolution plays a crucial role in astrophysics but bares large uncertainties. This problem becomes more severe by the majority of massive stars being born in close binary systems, whose evolution is affected by the interaction of their components. We want to constrain major uncertainties in massive binary star evolution, in particular the efficiency and the stability of the first mass transfer phase. We use the rapid population synthesis code ComBinE to generate synthetic populations of post-interaction binaries, assuming constant mass-transfer efficiency. We employ a new merger criterion that adjusts self-consistently to any prescribed mass-transfer efficiency. We tailor our synthetic populations to be comparable to the expected binary populations in the Small Magellanic Cloud (SMC). We find that the observed populations of evolved massive binaries can not be reproduced with a single mass-transfer efficiency. Instead, a rather high efficiency (>50%) is needed to reproduce the number of Be stars and Be/X-ray binaries in the SMC, while a low efficiency (~10%) leads to a better agreement with the observed number of Wolf-Rayet stars. We construct a corresponding mass-dependent mass-transfer efficiency recipe to produce our fiducial synthetic SMC post-interaction binary population. It reproduces the observed number and properties of the Be/X-ray and WR-binaries rather well, and is not in stark disagreement with the observed OBe star population. It further predicts two large, yet unobserved populations of OB+BH binaries, that is ~100 OB+BH systems with rather small orbital periods (<20 days) and ~40 longer period OBe+BH systems.

In the report by BICEP and Keck collaborations, the tensor-to-scalar ratio is $r_{0.05}<0.036$ (95\% C.L.) and $ <1.3\sigma$ non-zero (with pre-DESI BAO data). However, recent datasets have significantly shifted the bestfit values of relevant $\Lambda$CDM cosmological parameters, and thus possibly alter the amplitude of lensing B-mode spectrum, which would affect the search for $r$. Here, the joint analysis of Planck and BICEP/Keck data with DESI DR2 reveals that the lower bound of $r_{0.05}$ is $2.0\sigma$ and $2.1\sigma$ non-zero for PantheonPlus and DES-Y5, respectively, and the bestfit $r$ is $r_{0.05}\simeq 0.01$. The results are consistent with those with DESI DR1, but slightly strengthened. There might be still systematic uncertainties in B-mode measurements due to the foreground contamination, however, our work is to not say what about the value of $r$, but emphasize that the detection for $r$ is model-dependent and depends potentially on our insight into the dark universe, highlighting the important role of cosmological surveys in comprehending our very early universe.

The formation of first stars and galaxies at the Cosmic Dawn had been preceded by the chain of primordial chemistry reactions during Dark Ages which generated first molecules, mostly H$_2$, HD, and HeH$^+$, so crucial for first stars to emerge. These molecules absorbed and scattered CMB quanta this way distorting CMB spectrum. Estimate how much bound-bound transitions between the rovibrational levels of H$_2$, HD, and HeH$^+$ molecules contribute to the distortion of CMB spectrum in the standard $\Lambda$CDM cosmology. We describe the kinetics of the formation of the first molecules with system of 166 chemical reactions involving 20 reagents. The system of differential equations is solved to describe the processes of spontaneous and collisional transitions between rovibrational levels of H$_2$, HD, and HeH$^+$ molecules. The populations of rovibrational levels and optical thickness of the gas in transition lines between these levels were used to estimate the differential brightness produced by the first molecules on the cosmic microwave background. It is shown that the signal from the first molecules in the standard $\Lambda$CDM cosmology takes the form of an absorption profile in the CMB spectrum and originates from the Dark Ages. H$_2$ shows multiple peaks, peaking at $\sim 10^{-3}$ Jy/sr between 50-120 GHz, with absorption from $300>z>200$. HD has double peaks, reaching $\sim 10^{-5}$ Jy/sr between 40-70 GHz, with absorption from $300>z>30$. HeH$^+$ has no features, peaks at $\sim 10^{-7}$ Jy/sr between 200-800 GHz, and absorbs mainly from $100>z>4$.

It has been suggested that Jupiter's fuzzy core could be a result of a giant impact. Here, we investigate the expected impact conditions from N-body simulations. We then use state-of-the-art SPH simulations to investigate the results of impacts with different conditions including various impactor masses and composition, different formation stages in Jupiter's growth, and different resolutions. We next simulate the long-term thermal evolution of Jupiter post-impact. We find that N-body simulations predict rather oblique impacts, and that head-on collisions are rare. Moreover, our results show that even under a head-on collision, Jupiter's fuzzy core cannot be formed. We next simulated Jupiter's thermal evolution and showed that unless post-impact temperatures are extremely low, a giant impact would not lead to an extended dilute core as inferred by interior models. We conclude that Jupiter's fuzzy core is not caused by an impact and is likely to be an outcome of its formation process.

Context. Accurate photometric redshift (photo-z) estimation is crucial for cosmological and galaxy evolution studies, especially with the advent of large-scale photometric surveys. Aims. We develop a photo-z estimation code called TOPz (Tartu Observatory Photo-z) and apply it to the GAMA photometric catalogue. Methods. TOPz employs a Bayesian template-fitting approach to estimate photo-z from marginalised redshift posteriors. Using nine-band photometric data from the GAMA project, we assess the accuracy of TOPz by comparing its photo-z estimates to available spectroscopic redshifts. We generate synthetic galaxy spectra using the CIGALE software and run template set optimisation. We improve the photometry by applying flux and flux uncertainty corrections. An analytical prior is then imposed on the resulting posteriors to refine the redshift estimates. Results. The photo-z estimates produced by TOPz show good agreement with the spectroscopic redshifts. We demonstrate the redshift accuracy across various magnitude bins and test how the flux corrections and posteriors reflect the actual uncertainty of the estimates. We show that the TOPz results are consistent with those obtained from other photo-z codes applied to the same data set. Additionally, TOPz estimates stellar masses as a by-product, comparable to those calculated by other methods. We made the GAMA photo-z catalogue and all the codes and scripts used for the analysis and figures publicly available. Conclusions. TOPz is an advanced photo-z estimation code that integrates flux corrections, physical priors, and template set optimisation to provide state-of-the-art photo-z among competing template-based redshift estimators. Future work will focus on incorporating additional photometric data and applying the TOPz algorithm to J-PAS narrow-band survey, further validating and enhancing its capabilities.

Context. Young Stellar Objects (YSOs) are observed to undergo powerful accretion events known as FU Orionis outbursts (FUors). Such events of episodic accretion are now considered to be common during low mass star formation, wherein the accretion onto the protostar occurs through a surrounding centrifugal disk. Increasing evidence suggests that the magnetic disk winds are crucial for driving disk accretion, as they carry both mass and momentum away from the disk. Aims. We aim to investigate the phenomenon of the ejection of magnetic disk winds during episodic accretion, with a focus on the dust contained within these winds. Methods. We conduct magnetohydrodynamic (MHD) simulations of formation and evolution of protoplanetary disk (PPD) in the thin-disk limit. We include evolution of dust with two populations and a realistic prescription for viscosity during outbursts, which depends on the local thermal ionization fraction. The disk evolves with the concurrent action of viscosity, self-gravity and magnetic disk winds. Results. The simulated disk displays outbursting behavior in the early stages, with the duration and frequency of the bursts, their rise times, and brightness amplitudes resembling the observations of FUors. We find that during the outbursts, the winds are over an order of magnitude more dusty, as compared to in quiescence. However, despite this increased dust content, the winds are still dust-depleted as the dust-to-gas ratio is about an order of magnitude lower than the canonical interstellar value of 0.01. The results of our numerical experiments are in general agreement with the available observational findings and they shed a light on the mechanism behind production of dusty winds during outbursting events in YSOs.

We present the first overview of the expected quantity of signals which will showcase significant gravitational wave phase shifts caused by astrophysical environments, considering the upcoming A+ and A\# LIGO/Virgo/KAGRA, Cosmic Explorer and Einstein Telescope detectors. We construct and analyse two general families of dephasing prescriptions with extensions to eccentric sources, as well as collect five specific prescriptions for the fundamental smoking gun physical mechanisms at play in the dynamical and AGN formation channel for stellar mass binary black holes: Roemer delays, tidal forces and hydrodynamical interactions. We compute the expected fraction of signals containing astrophysical dephasing, as a function of environmental properties and based on observed distributions of binary parameters. We find that next generation detectors can expect to find environmental effects in hundreds of detected signals.

To exhume the buried signatures of free-floating planets (FFPs) with small angular Einstein radius $\theta_\mathrm{E}$, we build a new full-frame difference image for the Korean Microlensing Telescope Network (KMTNet) survey based on the newly optimized pySIS package. We introduce the detailed processes of the new pipeline, including frame registration, difference image analysis, and light curve extraction. To test this pipeline, we extract the light curves for 483,068 stars with $I \lesssim 17$ and conduct a model-independent search for microlensing events. The search finds 36 microlensing events, including five new events and six events discovered by other collaborations but missed by previous KMTNet searches. We find that the light curves from the new pipeline are precise enough to be sensitive to FFPs with $\theta_\mathrm{E} \sim 1~\mu$as. Using the new pipeline, a complete FFP search on the eight-year KMTNet images can be finished within six months and then yield the FFP mass function. The new pipeline can be used for a new KMTNet AlertFinder system, with significantly reduced false positives.

The field of astrophysics is continuously advancing, with an ever-growing influx of data requiring robust and efficient analysis tools. As the Square Kilometre Array (SKA) radio telescopes come fully operational, we anticipate the generation of hundreds of petabytes of data annually, characterized by unprecedented resolution and detail. In this context, scientific visualization becomes a critical component, enabling researchers to interpret complex datasets and extract meaningful insights. The immense volume of data demands not only suitable tools but also substantial infrastructure and computational capacity to analyze it effectively. In this work, we will discuss how we are addressing these challenges with the development of our interactive visualization tool named VisIVO Visual Analytics. The tool is transitioning from a local visualizer to a remote visualizer, utilizing a client-server architecture. This evolution will allow the software to run parallel visualization pipelines on high-performance computing (HPC) clusters, thereby enhancing its capacity to handle extensive datasets efficiently.

We investigate the dynamics of dust concentration in actively accreting, substructured, non-ideal MHD wind-launching disks using 2D and 3D simulations incorporating pressureless dust fluids of various grain sizes and their aerodynamic feedback on gas dynamics. Our results reveal that mm/cm-sized grains are preferentially concentrated within the inner 5-10 au of the disk, where the dust-to-gas surface density ratio (local metalicity Z) significantly exceeds the canonical 0.01, reaching values up to 0.25. This enhancement arises from the interplay of dust settling and complex gas flows in the meridional plane, including midplane accretion streams at early times, midplane expansion driven by magnetically braked surface accretion at later times, and vigorous meridional circulation in spontaneously formed gas rings. The resulting size-dependent dust distribution has a strong spatial variation, with large grains preferentially accumulating in dense rings, particularly in the inner disk, while being depleted in low-density gas gaps. In 3D, these rings and gaps are unstable to Rossby wave instability (RWI), generating arc-shaped vortices that stand out more prominently than their gas counterparts in the inner disk because of preferential dust concentration at small radii. The substantial local enhancement of the dust relative to the gas could promote planetesimal formation via streaming instability, potentially aided by the "azimuthal drift" streaming instability (AdSI) that operates efficiently in accreting disks and a lower Toomre Q expected in younger disks. Our findings suggest that actively accreting young disks may provide favorable conditions for early planetesimal formation, which warrants further investigation.

During the last seconds of a binary neutron-star merger, the tidal force can excite stellar oscillation modes to large amplitudes. From the perspective of premerger electromagnetic emissions and next-generation gravitational-wave detectors, gravity ($g-$) modes constitute a propitious class. However, existing estimates for their impact employ linear schemes which may be inaccurate for large amplitudes, as achieved by tidal resonances. With rotation, inertial modes can be excited as well and while their non-linear saturation has been studied, an extension to fully-consistent gravito-inertial modes, especially in the neutron-star context, is an open problem. We study the linear and non-linear saturation of gravito-inertial modes and investigate the astrophysical consequences for binary neutron-star mergers, including the possibility of resonance-induced dynamo activity. A new (non-)linear formulation based on the separation of equilibrium and dynamical tides is developed. Implementing this into the 3D pseudo-spectral code MagIC, a suite of non-linear simulations of tidally-excited flows with an entropy/composition gradient in a stably-stratified Boussinesq spherical-shell are carried out. The new formulation accurately reproduces results of linear calculations for gravito-inertial modes with a free surface for low frequencies. For a constant-density cavity, we show that the axisymmetric differential rotation induced by nonlinear $_2g$ and $_1g$ modes may theoretically be large enough to amplify an ambient magnetic field to $\gtrsim 10^{14}$ G. In addition, rich non-linear dynamics are observed in the form of a parametric instability for the $_1g$ mode. The stars are also spun-up, which extends the resonance window for any given mode.

Major advancements in space science and detector technology brought about a revolution in global astrometry, the science of measuring distances and motions of stars in the Milky Way and in the local universe. From the first ESA astrometric mission HIPPARCOS of the early 80s to the current Gaia mission, the data volume and computational complexity of the full reduction process has increased by several orders of magnitude, requiring high-performance computing and data throughput. We review the principles and computational complexity of general global astrometric models that lead to the statistical treatment of an extra-large, highly non-linear estimation problem. Some numerical aspects of inspecting Gaia's proper motions to find cosmological signals at all scales are also addressed.

Popular culture plays a significant role in shaping public interest in science, and Taylor Swift's discography frequently incorporates astrophysics terminology. This study examines the occurrence of astrophysics-related words in her lyrics and their representation in the Eras tour set list. By analyzing the frequency of words in Swift's total discography, we identify that astrophysics is promoted the most within her most recent album, The Tortured Poets Department, whereas songs from Midnights promoted astrophysics the most throughout the Eras tour. We catagorize words into various disciplines of astrophysics and find that multimessenger astronomy is promoted the most, both in Swift's total discography and throughout the Eras tour. We perform Taylor expansion and predict $12 \pm 5$ astrophysical terms in Swift's next album. This analysis offers a unique perspective on the intersection of music and science, revealing how Swift's artistry may unintentionally promote interest in different fields of astrophysics.

High angular resolution holds the key to extending our knowledge in several domains of astronomical research. In addition to the development of new instruments, advancements in post-processing algorithms can enhance the performances attainable in an observation, turning archival observations into a treasure. We developed a machine-learning tool, named zoom-in, that is able to improve the angular resolution of an astronomical image by a factor of $\sim 100$ by optimally recombining short-cadence sequences of images. After training our model on real-life photographs, we tested our method on archival images of the Moon taken through ESO instruments. We were able to achieve a remarkable spatial resolution of $\sim 1$ m of the lunar surface. While analyzing one of the fields from the sample, we discovered structures of clear anthropic origin inside the Aristarchus crater. The features appear to be consistent with ancient ruins of cities and castles. A thorough analysis of the relevant literature allowed us to conclude that this valley corresponds to the one described in Ludovico Ariosto's "Orlando Furioso": a place where all the items lost by humans gather and pile up. Analyses of the surface brightness from our images, indicating an abnormally high albedo of $\sim 0.25$, further corroborate this idea suggesting a conspicuous presence of glass. We infer the presence of >1 billion flasks of human wits on the lunar surface, whose origin we investigate in detail. We urge for a dedicated mission, astolfo, to be carried out by Artemis astronauts in order to recover human wits and bring them back to the Earth.

In an effort to reduce drain on grant funds and decrease unused space in publications, we have developed a Python package for inserting advertisements into the space left empty by corner plots. This novel technique can allow authors to reduce or eliminate publication charges for journals such as MNRAS and ApJ. In order to offset publication costs entirely, we recommend that authors include anywhere from 200-700 corner plots per paper, with the exact number depending on the journal used. Finally, we discuss other opportunities to generate ad revenue through publications.

When a relativistic jet is launched following the core-collapse of a star, its interaction with the stellar envelope leads to the formation of a hot cocoon, which produces various viewing-angle-dependent observational phenomena following the breakout from the surface. We study the observational signatures of fast X-ray transient (FXT) EP240414a, which may originate from a jet-cocoon system viewed slightly off-axis. In our model, (1) the prompt X-ray emission lasting $\sim\! 100\,{\rm{s}}$ is attributed to the cooling emission from the inner cocoon (shocked jet material); (2) the $\sim\! 0.1\,{\rm{d}}$ X-ray emission comes from the inner cocoon's afterglow; (3) the $\sim\! 0.4\,{\rm{d}}$ thermal-dominated optical emission arises from the cooling of the outer cocoon (shocked stellar material); (4) the $\sim\! 3\,{\rm{d}}$ non-thermal optical component and subsequent radio emission can be explained by the afterglow from a jet with a viewing angle of $10^{\circ}\lesssim \theta_{\rm{v}}\lesssim15^\circ$; and (5) the associated broad-lined Type Ic supernova only dominates the optical emission after $\sim\! 7\rm\, d$. Both the jet inferred from the off-axis afterglow and the inner cocoon constrained by the cooling emission are found to have similar kinetic energies, on the order of $10^{51}\,{\rm{erg}}$. We find that the progenitor's radius is $\sim3\,R_\odot$ as constrained by the { inner cocoon's} cooling emissions, indicating that the pre-explosion star may be a massive helium star that is slightly inflated. More FXTs associated with off-axis jets and supernovae will be further examined by the Einstein Probe, leading to a deeper understanding of jet-cocoon systems.

Intrinsic alignment (IA) of galaxies is a challenging source of contamination in the Cosmic shear (GG) signals. The galaxy intrinsic ellipticity-gravitational shear (IG) correlation is generally the most dominant component of such contamination for cross-correlating redshift bins. The self-calibration (SC) method is one of the most effective techniques to mitigate such contamination from the GG signal. In a photometric survey, the SC method first extracts the galaxy number density-galaxy intrinsic ellipticity (gI) correlation from the observed galaxy-galaxy lensing correlation using the redshift dependence of lens-source pairs. The IG correlation is computed through a scaling relation using the gI correlation and other lensing observables. We extend the SC method beyond the linear regime by modifying its scaling relation which can account for the non-linear galaxy bias model and various IA models. In this study, we provide a framework to detect the IG correlation for the redshift bins for source galaxies for the proposed year 1 survey of the Rubin Legacy Survey of Space and Time (LSST Y1). We tested the method for the tidal alignment and tidal torquing (TATT) model of IA and we found that the scaling relation is accurate within 10$\%$ and 20$\%$ for cross-correlating and auto-correlating redshift bins, respectively. Hence the suppression of IG contamination can be accomplished with a factor of 10 and 5, for cross-correlating and auto-correlating redshift bins, respectively. We tested the method's robustness and found that the suppression of IG contamination by a factor of 5 is still achievable for all combinations of cross-correlating bins even with the inclusion of a moderate amount of uncertainties on IA and bias parameters, respectively. [Abridged]

The spatial properties of the solar magnetic field are crucial to decoding the physical processes in the solar interior and their interplanetary effects. However, observations from older instruments, such as the Michelson Doppler Imager (MDI), have limited spatial or temporal resolution, which hinders the ability to study small-scale solar features in detail. Super resolving these older datasets is essential for uniform analysis across different solar cycles, enabling better characterization of solar flares, active regions, and magnetic network dynamics. In this work, we introduce a novel diffusion model approach for Super-Resolution and we apply it to MDI magnetograms to match the higher-resolution capabilities of the Helioseismic and Magnetic Imager (HMI). By training a Latent Diffusion Model (LDM) with residuals on downscaled HMI data and fine-tuning it with paired MDI/HMI data, we can enhance the resolution of MDI observations from 2"/pixel to 0.5"/pixel. We evaluate the quality of the reconstructed images by means of classical metrics (e.g., PSNR, SSIM, FID and LPIPS) and we check if physical properties, such as the unsigned magnetic flux or the size of an active region, are preserved. We compare our model with different variations of LDM and Denoising Diffusion Probabilistic models (DDPMs), but also with two deterministic architectures already used in the past for performing the Super-Resolution task. Furthermore, we show with an analysis in the Fourier domain that the LDM with residuals can resolve features smaller than 2", and due to the probabilistic nature of the LDM, we can asses their reliability, in contrast with the deterministic models. Future studies aim to super-resolve the temporal scale of the solar MDI instrument so that we can also have a better overview of the dynamics of the old events.

The formation and migration history of a planet is expected to be imprinted in its atmosphere, in particular its carbon-to-oxygen (C/O) ratio and metallicity. The BOWIE-ALIGN programme is performing a comparative study of JWST spectra of four aligned and four misaligned hot Jupiters, with the aim of characterising their atmospheres and corroborating the link between the observables and the formation history. In this work, we present the $2.8-5.2$ micron transmission spectrum of TrES-4b, a hot Jupiter with an orbit aligned with the rotation axis of its F-type host star. Using free chemistry atmospheric retrievals, we report a confident detection of H$_2$O at an abundance of $\log X_\mathrm{H_2O}=-2.98^{+0.68}_{-0.73}$ at a significance of $8.4\sigma$. We also find evidence for CO and small amounts of CO$_2$, retrieving abundances $\log X_\mathrm{CO}= -3.76^{+0.89}_{-1.01}$ and $\log X_\mathrm{CO_2}= -6.86^{+0.62}_{-0.65}$ ($3.1\sigma$ and $4.0\sigma$ respectively). The observations are consistent with the the atmosphere being in chemical equilibrium; our retrievals yield $\mathrm{C/O}$ between $0.30-0.42$ and constrain the atmospheric metallicity to the range $0.4-0.7\times$ solar. The inferred sub-stellar properties (C/O and metallicity) challenge traditional models, and could have arisen from an oxygen-rich gas accretion scenario, or a combination of low-metallicity gas and carbon-poor solid accretion.

The Photonic Lantern Nuller (PLN) is an instrument concept designed to characterize exoplanets within a single beam-width from its host star. The PLN leverages the spatial symmetry of a mode-selective photonic lantern (MSPL) to create nulled ports, which cancel out on-axis starlight but allow off-axis exoplanet light to couple. The null-depths are limited by wavefront aberrations in the system as well as by imperfections in the lantern. We show that the implicit electric field conjugation algorithm can be used to reduce the stellar coupling through the PLN by orders of magnitude while maintaining the majority of the off-axis light, leading to deeper null depths (~10^{-4}) and thus higher sensitivity to potential planet signals. We discuss a theory for the tradeoff we observed between the different ports, where iEFC improves the nulls of some ports at the expense of others, and show that targeting one port alone can lead to deeper starlight rejection through that port than when targeting all ports at once. We also observe different levels of stability depending on the port and discuss the implications for practically implementing this technique for science observations.

We use the ASTRID cosmological simulation to forecast massive black hole (MBH) binary mergers detectable by LISA. A key result is a significant increase in the predicted detection rate when MBH orbital eccentricity is included, rising from 5.6 for circular orbits to 10.5 events per year. This boost is largely due to inspiral sources that will merge after LISA's mission period, which make up 46% of detections in the eccentric case. This highlights LISA's sensitivity to early inspiral phases, especially for eccentric binaries that emit across a wider frequency band. Most LISA detections arise from $M_{\mathrm{BH}} \sim 10^{5-6}~\mathrm{M}_{\odot}$, low-redshift ($z<2$), low mass-ratio ($q\sim 0.01$--$0.1$) mergers, complementing instruments like Pulsar Timing Arrays (PTAs). Eccentricity also expands the detectable MBH mass range to $10^9~\mathrm{M}_{\odot}$ (from $10^8~\mathrm{M}_{\odot}$), and shifts the redshift peak from $z = 1.9$ (circular) to $z = 0.8$ (eccentric). We find LISA will detect MBH mergers in diverse host galaxies, including lower-mass and satellite galaxies. These hosts are $\sim 50$ times more star-forming than typical galaxies of the same mass, forming a tight power-law in SFR--$M_{\rm gal}$ space: ${\rm SFR} = 10^{-8} M_{\rm gal}^{0.9}~\mathrm{M}_{\odot}\,\mathrm{yr}^{-1}$, independent of redshift. This contrasts with expectations for PTA sources, which tend to reside in massive central galaxies, suggesting LISA will probe distinct galactic environments. Only $\sim 10\%$ of the remnant MBHs are bright AGNs, mostly from mergers with $M_{\mathrm{BH}} > 10^{6.5}~\mathrm{M}_{\odot}$.

Spectra of the nearly edge-on protoplanetary disks observed with the JWST have shown ice absorption bands of varying optical depths and peculiar profiles, challenging radiative transfer modelling and our understanding of dust and ice in disks. We build models including dust grain size, shape, and composition to reproduce JWST IFU spectroscopy of the large edge-on disk Tau042021. We explore radiative transfer models using different dust grain size distributions, including grains of effective radii a_eff = 0.005-3000 microns. Scattering properties of distributions of triaxial ellipsoidal grains are calculated. We consider compositions with silicates, amorphous carbon, and mixtures of H2O, CO2, and CO. We use RADMC-3D Monte Carlo radiative transfer models of Tau042021 to simulate the spectral cubes observed with JWST-NIRSpec and MIRI. We compare the results to observations, including H2O at 3.05 microns, CO at 4.67 microns, and CO2 at 4.27 microns and to archival JWST-NIRCam and ALMA continuum images. The observed near- to mid-infrared imply dust distributions with grain sizes up to several tens of microns. The intensity distribution perpendicular to the disk exhibits emission profile wings extending into the upper disk atmosphere at altitudes exceeding the classical scale height expected in the isothermal hydrostatic limit. We produce ice map images demonstrating the presence of icy dust grains up to altitudes high above the disk midplane, more than three hydrostatic equilibrium scale heights. We demonstrate the presence of a wind containing the carriers of astronomical PAH bands. The wind appears as an X-shaped emission at 3.3, 6.2, 7.7 and 11.3 microns, characteristic wavelengths of the infrared astronomical PAH bands. We associate the spatial distribution of this component with carriers of astronomical PAH bands that form a layer of emission at the interface with the H2 wind.

The Lyman-break technique has been used to successfully identify high-redshift candidates in broad-band photometric data in the rest-frame optical and NIR using the dropout technique. We pioneer the application of this technique to new wavelength regimes, and search for dropouts in combined ALMA and JWST data. We find a candidate that is undetected in NIRCam imaging including and blueward of the F444W filter, but clearly identified in ALMA band 3. Assuming this is a Lyman-break candidate, we measure a redshift in the range $40 < z < 21\,380$. This is the highest redshift galaxy candidate discovered to date, and is in significant tension with current and future predictions from cosmological simulations, with implications for galaxy evolution in the (very) early Universe.

Dense filaments are believed to be representative of the initial conditions of star formation in molecular clouds. We have used the MIRI instrument on JWST to image the massive filament NGC6334M at d~1.3 kpc with unprecedented resolution and dynamic range at 7.7 and 25.5 microns. Our observations reveal the fine structure of the filament in absorption against mid-infrared background emission. From the absorption data, we derive high-resolution column density maps and perform a detailed analysis of the filament structure. We find a median filament width of 0.12+/-0.02 pc at both wavelengths, resolved by almost two orders of magnitude by MIRI, and consistent with the typical half-power width of Herschel filaments in nearby (d<0.5 kpc) clouds. The JWST data also reveal the presence of a quasi-periodic series of side filaments with a similar projected spacing of 0.125+/-0.015 pc. Combining our JWST results with Spitzer and APEX/Herschel data, we perform a study of cloud structure over four orders of magnitude in linear scale. A convergence test shows that our width estimates for NGC6334M are robust and reflect the presence of a true characteristic scale. While there is evidence of a Kolmogorov-like spectrum of small-scale fluctuations down the 1.6x10^-3 pc resolution of the JWST observations, we identify a break in the power spectrum of column density fluctuations at a scale ~0.1-0.4 pc comparable to the width of NGC6334M and its side filaments. This characteristic scale ~0.1pc has important implications for the origin of the star formation efficiency in dense gas and the IMF.

Recently the Dark Energy Spectroscopic Instrument (DESI) provided constraints on the expansion history from their Data Release 2 (DR2). The DESI baryon acoustic oscillation (BAO) measurements are well described by a flat $\Lambda$CDM model, but the preferred parameters are in mild ($2.3\sigma$) tension with those determined from the cosmic microwave background (CMB). The DESI collaboration has already explored a variety of solutions to this tension relying on variations in the late-time evolution of dark energy. Here we test an alternative -- the introduction of an ``early dark energy'' (EDE) component. We find that EDE models can alleviate the tension, though they lead to differences in other cosmological parameters that have observational implications. Particularly the EDE models that fit the acoustic datasets prefer lower $\Omega_m$, higher $H_0$, $n_s$ and $\sigma_8$ in contrast to the late-time solutions. We discuss the current status and near-future prospects for distinguishing amongst these solutions.

Supermassive black holes at the centre of galaxies gain mass through accretion disks. Models predict that quasi-spherical winds, expelled by the black hole during active accretion phases, have a key role in shaping galaxy evolution by regulating star formation, the distribution of metals over kiloparsec scales, and by sweeping ambient gas to the outskirts and beyond of galaxies. Nonetheless, the mechanism driving these outflows and the amount of energy exchanged between the wind and the galaxy's interstellar medium remain unclear. Here, we present a detailed analysis of the kinematical properties of winds in a sample of nearby active galaxies using the novel kinematic tool MOKA3D, which takes into account the clumpy nature of the ISM. We find remarkable similarities among the properties of the outflows in all the galaxies examined. In particular, we provide the first evidence that outflows exhibit a regular trend in radial velocity, initially constant or slightly decreasing, followed by rapid acceleration starting at approximately 1 kpc from the nucleus, despite the seemingly complex kinematics observed. The observed behavior aligns with our current theoretical understanding of Active Galactic Nuclei outflows, where a momentum-driven phase transitions to an energy-conserving phase just beyond approximately 1 kpc. The constant velocity of the momentum-driven wind is then rapidly accelerated following the inefficient Compton cooling of post-shock material and the transition to energy conservation. The measured radial terminal velocities of the outflows are always larger than the escape velocities from the host galaxies, confirming the key role of outflows in shaping the galaxy properties and evolution, as a manifestation of AGN feedback. Our results, only made possible by our novel kinematic analysis tool, are crucial to understand the origin and the powering mechanism of these winds.

The intrabinary shocks (IBS) of spider pulsars emit non-thermal synchrotron X-rays from accelerated electrons and positrons in the shocked pulsar wind, likely energized by magnetic reconnection. In redback spider pulsars, the IBS typically wraps around the sub-stellar companion, leading to a near-normal IBS shock with relatively bright X-ray emission. The characteristic energies of radiating particles and the magnetic fields in the IBS suggest spectral features in the hard X-ray band. Here we perform joint soft-hard X-ray analyses of three redback pulsars, J1723-2837, J2215+5135, and J2339-0533, including new J2215 NuSTAR data. We identify a significant cooling break in J1723-2837 and a marginal break in J2215+5135, while placing constraints on the break energy in J2339-0533. Interpreting these as synchrotron cooling features allows us to estimate the IBS magnetic field $B_{\rm IBS} \sim 40-100$ G and place lower bounds on the maximum radiating electron energy. Our results constrain the magnetization of the pulsar wind as well as pair-production in millisecond pulsar magnetospheres.

We use a Hybrid Effective Field Theory (HEFT) model to constrain the evolution of low-redshift $(z\lesssim0.4)$ matter fluctuations by cross-correlating DESI Bright Galaxy Survey (BGS) legacy imaging with the latest CMB lensing maps from Planck and ACT. Our tomographic BGS analysis finds that the evolution and amplitude of matter fluctuations align with CMB-conditioned $\Lambda$CDM predictions. When including DESI Baryon Acoustic Oscillation (BAO) measurements we obtain $\sigma_8 = 0.876^{+0.051}_{-0.067}$ from BGS alone. Jointly analyzing BGS and Luminous Red Galaxy (LRG) cross-correlations with the same CMB lensing maps yields $\sigma_8 = 0.791\pm0.021$. As a complementary approach we isolate the galaxy magnification signal from the cross-correlation of non-overlapping BGS and LRG photometric redshift bins, ruling out the null-magnification hypothesis at $11\sigma$. For the first time, we constrain structure growth from the (finite-difference calibrated) galaxy magnification signal and find $\sigma_8=0.720\pm0.047\,\,({\rm stat.})\pm0.050\,\,({\rm sys.})$ when adopting a linear bias model and including BAO data.

We discuss a simple theory for physics beyond the Standard Model where a Majorana dark matter is predicted from anomaly cancellation. We discuss in detail the minimal theory where the baryon number is a local symmetry spontaneously broken at the low scale. The correlation between the cosmological constraints on the dark matter relic density, the direct detection and collider bounds is investigated. We discuss in great detail the gamma lines from dark matter annihilation showing the possibility to test these predictions in the near future at gamma-ray telescopes such as CTA. We investigate all processes contributing to the total photon flux from dark matter annihilation and point out the unique features that can be used to test this theory for dark matter.

We investigate the spectral behavior of scalar fluctuations generated by gravity during inflation and the subsequent reheating phase. We consider a non-perturbative Bogoliubov treatment within the context of pure gravitational reheating. We compute both long and short-wavelength spectra, first for a massless scalar field, revealing that the spectral index in part of the infrared (IR) regime varies between $-6$ and $-3$, depending on the post-inflationary equation of state (EoS), $0\leq w_\phi\leq1$. Furthermore, we study the mass-breaking effect of the IR spectrum by including finite mass, $m_{\chi}$, of the daughter scalar field. We show that for $m_{\chi}/H_{\rm e} \gtrsim 3/2$, where $H_{\rm e}$ is the Hubble parameter during inflation, the IR spectrum of scalar fluctuations experiences exponential mass suppression, while for smaller masses, $m_{\chi}/\He<3/2$, the spectrum remains flat in the IR regime regardless of the post-inflationary EoS. For any general EoS, we also compute a specific IR scale, $k_m$, of fluctuations below which the IR spectrum will suffer from this finite mass effect. In the UV regime, oscillations of the inflaton background lead to interference terms that explain the high-frequency oscillations in the spectrum. Interestingly, we find that for any EoS, $1/9 \lesssim w_\phi \lesssim 1$, the spectral behavior turns out to be independent of the EoS, with a spectral index $ -6$. We have compared this Bogoliubov treatment for the UV regime to perturbative computations with solutions to the Boltzmann equation and found an agreement between the two approaches for any EoS, $0 \lesssim w_\phi \lesssim 1$. We also explore the relationship between the gravitational reheating temperature and the reheating EoS employing the non-perturbative analytic approach, finding that reheating can occur for $w_\phi \gtrsim 0.6$.

The cosmological principle posits that the universe does not exhibit any specific preference for position or direction. However, it remains unclear whether the universe has a distinct preference for parity: whether certain properties are more likely to be classified as even or odd. In this study, we analyze the largest available galaxy group catalogs to explore this hypothesis: specifically, whether the number of galaxies within a galaxy group or cluster is more likely to be odd or even. Our findings convincingly indicate that the universe indeed favors odd numbers, with results achieving a significance level well above the $4.1-\sigma$ threshold.

We investigate the dynamics of test particles, perturbations, and greybody factors within the framework of a Bardeen-like AdS black hole (BH) with a phantom global monopole. This study explores the interactions between nonlinear electrodynamics, the energy scale of symmetry breaking, and space-time topology. We analyze the geodesic motion of null and time-like particles, deriving effective potentials that describe their trajectories. Utilizing the Regge-Wheeler potential, we calculate the quasinormal modes (QNMs) for scalar, vector, and tensor perturbations, applying the sixth-order WKB approximation. Our findings highlight how the Bardeen-like parameter ($\mathrm{b}$) and the energy scale of symmetry breaking, characterized by the parameter ($\eta$), influence the QNM spectra, with potential implications for gravitational wave observations. We also examine greybody factors, focusing on the transmission and reflection coefficients for scalar and axial fields, and employ semi-analytic techniques to derive precise bounds. Furthermore, we assess the thermodynamic stability of the BH, emphasizing the role of these parameters in phase transitions and stability criteria.

Rotating black holes can amplify ultralight bosonic fields through superradiance, forming macroscopic clouds known as gravitational atoms. When the cloud forms around one of the components of a binary system, it can undergo a series of distinctive interactions, comprising both secular effects, such as dynamical friction or accretion, and resonant behaviour. These processes are expected to leave a distinctive signature on the gravitational waveform emitted by the binary, whose detectability we investigate in this paper. To do so, we implement a numerical code that integrates these effects, computed within a Newtonian approximation, for intermediate-to-high mass-ratio binaries on circular equatorial orbits. Realistic waveforms incorporating these environmental influences are generated and analyzed using the Fisher matrix formalism to evaluate the detectability of bosonic clouds with current and next-generation ground-based gravitational wave observatories. Our results demonstrate the potential for gravitational wave astronomy to probe the existence and properties of ultralight bosons.

For generations, people have complained that things used to be better in the past. In this paper, we investigate this change by specifically looking at creativity in astronomy. To do this,we explore if older constellations reflected a greater sense of creativity on the part of those designing them than more modern constellations do. We find that things really have become simplistic and less original over time.

Space-Time Projection (STP) is introduced as a data-driven forecasting approach for high-dimensional and time-resolved data. The method computes extended space-time proper orthogonal modes from training data spanning a prediction horizon comprising both hindcast and forecast intervals. Forecasts are then generated by projecting the hindcast portion of these modes onto new data, simultaneously leveraging their orthogonality and optimal correlation with the forecast extension. Rooted in Proper Orthogonal Decomposition (POD) theory, dimensionality reduction and time-delay embedding are intrinsic to the approach. For a given ensemble and fixed prediction horizon, the only tunable parameter is the truncation rank--no additional hyperparameters are required. The hindcast accuracy serves as a reliable indicator for short-term forecast accuracy and establishes a lower bound on forecast errors. The efficacy of the method is demonstrated using two datasets: transient, highly anisotropic simulations of supernova explosions in a turbulent interstellar medium, and experimental velocity fields of a turbulent high-subsonic engineering flow. In a comparative study with standard Long Short-Term Memory (LSTM) neural networks--acknowledging that alternative architectures or training strategies may yield different outcomes--the method consistently provided more accurate forecasts. Considering its simplicity and robust performance, STP offers an interpretable and competitive benchmark for forecasting high-dimensional transient and chaotic processes, relying purely on spatiotemporal correlation information.

We all love the ecstasy that comes with submitting papers to journals or arXiv. Some have described it as yeeting their back-breaking products of labor into the void, wishing they could never deal with them ever again. The very act of yeeting papers onto arXiv contributes to the expansion of the arXiverse; however, we have yet to quantify our contribution to the cause. In this work, I investigate the expansion of the arXiverse using the arXiv astro-ph submission data from 1992 to date. I coin the term "the arXiverse constant", $a_0$, to quantify the rate of expansion of the arXiverse. I find that astro-ph as a whole has a positive $a_0$, but this does not always hold true for the six subcategories of astro-ph. I then investigate the temporal changes in $a_0$ for the astro-ph subcategories and astro-ph as a whole, from which I infer the fate of the arXiverse.

I report the discovery of jacquetium ($_0$Jq), the first naturally occurring element found since more than 80 years.

Current leading theories of physics such as the Big Bang, the standard model of particle physics, and general relativity suggest that the universe should contain an equal amount of matter and antimatter. Yet observations have found a disproportionately large amount of matter, a phenomenon known as the baryon assymmetry problem. Since century-old established theories are traditionally impossible to refute, the only possible explanation is that the remaining antimatter is hidden in plain sight and remains to be observed. We propose the existence of anti-stars to solve the baryon assymetry in our new Reasonable Antimatter Theory of Stars (RATS). In this context, the RATS will create a framework to resolve the traditional tension between observers and theorists, and thus contribute to the peaceful and collaborative spirit of astronomy. Our method is the firing of neurons in our brains, typically known as a thought experiment. We still have no idea why or how this works, but it must be good because most of science was created this way. Our results are the result of our methods, which result in some text and the resulting conclusions. In order to encourage the reader to reach the end of this short paper, we do not want to spoil the conclusions here. Instead, the conclusions will conclude the paper.

In this work we apply the gravity-thermodynamics approach for the case of generalized mass-to-horizon entropy, which is a two-parameter extension of Bekenstein-Hawking entropy that arises from the extended mass-to-horizon relation, that is in turn required in order to have consistency with the Clausius relation. We extract the modified Friedmann equations and we obtain an effective dark energy sector arising from the novel terms. We derive analytical solutions for the dark energy density parameter, the dark energy equation-of-state parameter, and the deceleration parameter, and we show that the Universe exhibits the usual thermal history with the succession of matter and dark energy epochs. Additionally, depending on the value of the entropy parameters, the dark energy equation-of-state parameter can either lie in the phantom regime at high redshifts entering into the quintessence regime at small redshifts, or it can lie in the quintessence regime at high redshifts and experience the phantom-divide crossing at small redshifts, while in the far future in all cases it asymptotically obtains the cosmological constant value $-1$. Finally, we perform observational confrontation with Supernova Type Ia (SNIa), Cosmic Chronometers (CC) and Baryonic Acoustic Oscillations (BAO) datasets, showing that the scenario is in agreement with observations.