Papers for Friday, Jul 25 2025

We examine the funding disparity in astronomical research priorities: the Habitable Worlds Observatory is planned to receive over $10 billion over the next two decades whereas extraterrestrial intelligence research receives nearly zero federal funding. This imbalance is in contrast to both scientific value and public interest, as 65% of Americans and 58.2% of surveyed astrobiologists believe extraterrestrial intelligence exists. Empirical psychological research demonstrates that humanity possesses greater resilience toward extraterrestrial contact than historically recognized. Contemporary studies reveal adaptive responses rather than mass panic, conflicting with the rationale for excluding extraterrestrial intelligence research from federal funding since 1993. The response to the recent interstellar object 3I/ATLAS exemplifies consequences of this underinvestment: despite discovery forecasts of a new interstellar object every few months for the coming decade, no funded missions exist to intercept or closely study these visitors from outside the Solar System. We propose establishing a comprehensive research program to explore both biosignatures and technosignatures on interstellar objects. This program would address profound public interest while advancing detection capabilities and enabling potentially transformative discoveries in the search for extraterrestrial life. The systematic exclusion of extraterrestrial intelligence research represents institutional bias rather than scientific limitation, requiring immediate reconsideration of funding priorities.

The Galactic Center Excess (GCE) remains one of the defining mysteries uncovered by the Fermi $\gamma$-ray Space Telescope. Although it may yet herald the discovery of annihilating dark matter, weighing against that conclusion are analyses showing the spatial structure of the emission appears more consistent with a population of dim point sources. Technical limitations have restricted prior analyses to studying the point-source hypothesis purely spatially. All spectral information that could help disentangle the GCE from the complex and uncertain astrophysical emission was discarded. We demonstrate that a neural network-aided simulation-based inference approach can overcome such limitations and thereby confront the point source explanation of the GCE with spatial and spectral data. The addition is profound: energy information drives the putative point sources to be significantly dimmer, indicating either the GCE is truly diffuse in nature or made of an exceptionally large number of sources. Quantitatively, for our best fit background model, the excess is essentially consistent with Poisson emission as predicted by dark matter. If the excess is instead due to point sources, our median prediction is ${\cal O}(10^5)$ sources in the Galactic Center, or more than 35,000 sources at 90% confidence, both significantly larger than the hundreds of sources preferred by earlier point-source analyses of the GCE.

We report the discovery of recurrent activity on quasi-Hilda comet (QHC) 362P/(457175) 2008 GO98. The first activity epoch was discovered during the perihelion passage of 362P. The first activity epoch was discovered during the perihelion in 2016 (Garcia-Migani & Gil-Hutton 2018), so we were motivated to observe it for recurrent cometary activity near its next perihelion passage (UT 2024 July 20). We obtained observations with the Lowell Discovery Telescope (LDT), the Astrophysical Research Consortium (ARC) telescope, and the Vatican Advanced Technology Telescope (VATT) and identified a second activity epoch when 362P had a true anomaly (v) as early as 318.1 deg. We conducted archival searches of numerous repositories and identified images obtained with Canada-France-Hawaii Telescope (CFHT) MegaCam, Dark Energy Camera (DECam), Pan-STARRS 1, SkyMapper, Zwicky Transient Facility (ZTF), and Las Cumbres Observatory Global Telescope (LCOGT) network data. Using these data, we identified activity from a previously unreported timespan, and we did not detect activity when 362P was away from perihelion, specifically 83 deg < v < 318 deg. Detection of activity near perihelion and absence of activity away from perihelion suggest thermally-driven activity and volatile sublimation. Our dynamical simulations suggest 362P is a QHC and it will remain in a combined Jupiter-family comet (JFC) and quasi-Hilda orbit over the next 1 kyr, though it will become increasingly chaotic nearing the end of this timeframe. Our backward simulations suggest 362P may have migrated from the orbit of a Long Period Comet (~53%) or Centaur (~32%), otherwise it remained a JFC (~15%) over the previous 100 kyr. We recommend additional telescope observations from the community as 362P continues outbound from its perihelion on UT 2024 July 20, as well as continued observations for a third activity epoch.

Over the past few years \textit{JWST} has been a major workhorse in detecting and constraining the metal enrichment of the first galaxies in the early Universe and finding the source of the ionisation of their interstellar medium. In this work, we present new deep JWST/NIRSpec spectroscopy of GS-z11-1, a galaxy at z = 11.28, in which we report the detection of multiple rest-frame UV and optical emission lines: CIII]$\lambda\lambda$1907,09, CIV]$\lambda\lambda$1548,51, [OII]$\lambda\lambda$3726,29, [NeIII]$\lambda$3869, H$\gamma$ and tentative evidence for HeII$\lambda$1640. The ionisation properties of GS-z11-1 are consistent with star formation, with potential contribution from an active galactic nucleus (AGN). We estimate a galaxy stellar mass of log(M$_{*}$/M$_{\odot}$) = 7.8$\pm$0.2 and log(SFR/(M$_{\odot}$ yr$^{-1}$))= 0.32$\pm$0.11 for the fiducial SF-only models. We measured C/O from the SED modelling of C/O = 1.20$\pm0.15 \times$ solar. This is one of the highest C/O abundances at z$>$10, and it is consistent with either PopII and PopIII enrichment paths. Despite this source being extremely compact, with a half-light radius of 73$\pm$10 pc, we see no increased equivalent width of NIV] and NIII] emission lines as seen in some other compact sources at similar redshifts, a potential signature of second-generation stars in GCs. Overall, this galaxy exhibits low metallicity and high ionisation parameter consistent with intense star-formation or AGN activity in the early Universe, possibly observed before the enrichment by the second generation of stars in proto-globular clusters in the core of the galaxy.

Supergiant B[e] (sgB[e]) stars are exceptionally rare objects, with only a handful of confirmed examples in the Milky Way. The evolutionary pathways leading to the sgB[e] phase remain largely debated, highlighting the need for additional observations. The sgB[e] star Wd1-9, located in the massive cluster Westerlund 1 (Wd1), is enshrouded in a dusty cocoon--likely the result of past eruptive activity--leaving its true nature enigmatic. We present the most detailed X-ray study of Wd1-9 to date, using X-rays that pierce through its cocoon with the aim to uncover its nature and evolutionary state. We utilize 36 Chandra observations of Wd1 from the 'Extended Westerlund 1 and 2 Open Clusters Survey' (EWOCS), plus eight archival datasets, totalling 1.1 Ms. This dataset allows investigation of long-term variability and periodicity in Wd1-9, while X-ray colours and spectra are analysed over time to uncover patterns that shed light on its nature. Wd1-9 exhibits significant long-term X-ray variability, within which we identify a strong 14-day periodic signal. We interpret this as the orbital period, marking the first period determination for the system. The X-ray spectrum of Wd1-9 is thermal and hard (kT approximately 3.0 keV), resembling the spectra of bright Wolf-Rayet (WR) binaries in Wd1, while a strong Fe emission line at 6.7 keV indicates hot plasma from a colliding-wind X-ray binary. Wd1-9, with evidence of past mass loss, circumbinary material, a hard X-ray spectrum, and a newly detected 14-day period, displays all the hallmarks of a binary--likely a WR+OB--that recently underwent early Case B mass transfer. Its sgB[e] classification is likely phenomenological reflecting emission from the dense circumbinary material. This places Wd1-9 in a rarely observed phase, possibly revealing a newly formed WN star, bridging the gap between immediate precursors and later evolutionary stages in Wd1.

A key result from JWST's first cycles is that galaxy formation was well underway by $z=10$. The implications of these early galaxies for reionization are less clear, however. The CMB is one of the few windows into the ionization state of the IGM during reionization's first half, providing an important probe of the ionizing photon sources at those times. Meanwhile, measurements of the Lyman-$\alpha$ forest in the spectra of high-$z$ quasars have improved to the level of tightly constraining the timing of reionization's end. In this paper, we use radiative transfer simulations to explore how measurements of the patchy kinetic Sunyaev Zel'dovich (pkSZ) effect, when combined with Lyman-$\alpha$ forest measurements, can be used to constrain the early stages of reionization and the nature of its sources. For a given source model, we find that the amplitude of the pkSZ power spectra strongly correlates with the start time of reionization, and constrains the number of ionizing photons produced by the high-$z$ source population. Allowing for variations in the source model, this correlation is weakened by a degeneracy between the reionization history and the effects of source clustering. However, we demonstrate two potential ways of breaking this degeneracy using: (1) measurements of large-scale fluctuations in the Ly$\alpha$ forest opacity at $z=5-6$, and/or; (2) the shape of the pkSZ power spectrum measured in future CMB surveys. Models with highly clustered sources yield steeper slopes in the pkSZ power around $\ell = 3,000$, so measurements at additional angular scales can be used to break the history-clustering degeneracy. Our results highlight how future pkSZ measurements will complement JWST observations to improve our understanding of the ionizing sources near cosmic dawn.

Simulating black hole (BH) accretion and feedback from the horizon to galactic scales is extremely challenging, as it involves a vast range of scales. Recently, our multizone method has successfully achieved global dynamical steady-states of hot accretion flows in three-dimensional general relativistic magnetohydrodynamic (GRMHD) simulations by tracking the bidirectional interaction between a non-spinning BH and its host galaxy. In this paper, we present technical improvements to the method and apply it to spin $a_*=0.9$ BHs, which power relativistic jets. We first test the new multizone set-up with a smaller Bondi radius, $R_B\approx400\,r_g$, where $r_g$ is the gravitational radius. The strongly magnetized accretion launches a relativistic jet with an intermediate feedback efficiency $\eta\sim30\,\%$, in between that of a prograde ($\eta\sim100\,\%$) and retrograde ($\eta\sim 10\,\%$) torus. Interestingly, both prograde and retrograde simulations also eventually converge to the same intermediate efficiency when evolved long enough, as accumulated magnetic fields remove gas rotation. We then extend strongly magnetized simulations to larger Bondi radii, $R_B\approx 2\times10^3,~2\times 10^4,~2\times 10^5\,r_g$. We find that the BH accretion rate $\dot{M}$ is suppressed with respect to the Bondi rate $\dot{M}_B$ as $\dot{M}/\dot{M}_B\propto R_B^{-1/2}$. However, despite some variability, the time-averaged feedback efficiency is $\eta\sim30\,\%$, independent of $R_B$. This suggests that BH feedback efficiency in hot accretion flows is mainly governed by the BH spin ($a_*$) rather than by the galactic properties ($R_B$). From these first-principles simulations, we provide a feedback subgrid prescription for cosmological simulations: $\dot{E}_{\rm fb}=2\times10^{-3}[R_B/(2\times10^5\,r_g)]^{-1/2}\dot{M}_Bc^2$ for BH spin $a_*=0.9$.

Star formation from metal-free gas, the hallmark of the first generation of Population III stars, was long assumed to occur in the very early Universe. We report the discovery of MPG-CR3 (Metal-Pristine Galaxy COSMOS Redshift 3; hereafter CR3), an extremely metal-poor galaxy at redshift $z= 3.193\pm0.016$. From JWST, VLT, and Subaru observations, CR3 exhibits exceptionally strong Ly$\alpha$, H$\alpha$, and He I $\lambda$10830 emission. We measure rest-frame equivalent widths of EW$_0$(Ly$\alpha$) $\approx822$ Angstrom and EW$_0$(H$\alpha$) $\approx2814$ Angstrom, among the highest seen in star-forming systems. No metal lines, e.g. [O III] $\lambda\lambda4959,5007$, C IV $\lambda\lambda1548,1550$, are currently detected at statistically significant level, placing a 2-$\sigma$ abundance upper limit of 12+log(O/H) < 6.52 ($Z < 8\times10^{-3}\ Z_\odot$). The observed Ly$\alpha$/H$\alpha$ flux ratio is $\approx13.9$, indicating negligible dust attenuation. Spectral energy distribution modeling with Pop III stellar templates indicates a very young ($\sim2$ Myr), low-mass ($M_* \approx 6.1\times 10^5 M_\odot$) stellar population. Further, the photometric redshifts reveal that CR3 could reside in a slightly underdense environment ($\delta \approx -0.12$). CR3 provides evidence that first-generation star formation could persist well after the epoch of reionization, challenging the conventional view that pristine star formation ended by $z\gtrsim6$.

Gamma-Ray Bursts (GRBs) are the strongest explosions in the Universe, and are powered by initially ultra-relativistic jets. The angular profile of GRB jets encodes important information about their launching and propagation near the central source, and can be probed through their afterglow emission. Detailed analysis of the multi-wavelength afterglow light curves of recent GRBs indeed shows evidence for an extended angular structure beyond the jet's narrow core. The afterglow emission is determined by the jet angular structure, our viewing angle, and the magnetic field structure behind the shock, often leading to degeneracies when considering the light curves and broad-band spectrum alone. Such degeneracies can be lifted with joint modeling of the afterglow light curves and polarization. In this work we study the evolution of the afterglow linear polarization and flux density from steep, core-dominated GRB jets, where most of their energy resides within a narrow core. We explore the dependence of the light and polarization curves on the viewing angle, jet angular energy structure and magnetic field configuration, and provide an analytical approximation for the peak polarization level, which occurs at a time close to that of a break in the light curve. Finally, we demonstrate how our results can be used to determine the nature of orphan GRB afterglows, distinguishing between a quasi-spherical "dirty fireball" and a steep jets viewed far off-axis and apply them on the Zwicky Transient Facility (ZTF) detected orphan afterglow candidate AT2021lfa.

Cosmic strings appear in many well-motivated extensions to the standard model of particle physics. If they exist, an abundant population of compact objects known as cosmic string loops permeate the Universe at all times, providing a secondary source of density perturbations that are large amplitude and non-gaussian in nature. In general, these loops are not stationary in the rest frame of the dark matter, thus their relative velocities will typically seed both spherical and filamentary overdensities in the matter era. Building upon previous work, we provide an improved framework to compute the complete halo mass function for these string seeded overdensities, valid for any loop velocity distribution. Using this mass function, we also compute the subset of halos capable of undergoing a direct collapse, forming a population of black holes with initial mass $10^{4-5} \, M_{\odot}$ at high redshifts. Interestingly, for reasonable values of the string parameters, one can reproduce the abundance of ``Little Red Dots" as inferred by JWST.

We investigate the neutrino and gravitational wave (GW) signals from accretion disks formed during the failed collapse of a rotating massive star (a collapsar). Following black hole formation, a neutrino-cooled, shocked accretion disk forms, which displays non-spherical oscillations for a period of seconds before becoming advective and exploding the star. We compute the neutrino and GW signals (matter quadrupole) from collapsar disks using global axisymmetric, viscous hydrodynamic simulations. The neutrino signal with typical energies of O$(10)$ MeV is maximal during the neutrino-cooled (NDAF) phase that follows shock formation. This phase lasts for a few seconds and is easily detectable within O$(10-100)$ kpc by the IceCube Neutrino Telescope. Additional neutrino signatures from a precursor equatorial shock and by stochastic accretion plumes during the advective phase are detectable within the galaxy. The GW signal during the NDAF phase is detectable in the galaxy by current and next-generation ground-based observatories. The explosion (memory) GW signal is similar to that of standard core-collapse supernovae and can be probed with a deci-Hertz space-based detector. Shock oscillations during the NDAF phase impart time variations with frequency O$(10-100)$ Hz to the neutrino and GW signals, encoding information about the shock dynamics and inner disk. These time variations can be detectable in neutrinos by IceCube within O$(1-10)$ kpc depending on progenitor model, flavor transformation scenario, and detailed properties of the angular momentum transport mechanism.

The incidence rate of Mg II absorbers per unit redshift path (dN/dz) towards quasar sightlines has been used to probe the interaction between quasar jets and surrounding gas clouds. Studies using core- and lobe-dominated samples found a higher dN/dz for strong Mg II absorbers (rest equivalent width, W_r(2796) >= 1.0 A) in velocity offsets ranging from 5000 km/s < beta * c < 60000 km/s (with beta = v/c), toward core-dominated sources. In this study, we applied a stringent spectral index criterion: alpha_radio < -0.7 for steep-spectrum radio quasars (SSRQs) and alpha_radio > -0.3 for flat-spectrum radio quasars (FSRQs). Using this, we assembled the largest sample to date: 441 FSRQs and 464 SSRQs with suitable optical spectra to study both strong absorbers and weak (0.3 A < W_r(2796) < 1.0 A) Mg II absorbers. We conducted a detailed comparison of absorbers' incidence rate and offset velocity distributions. Our main findings are: (i) For both weak and strong absorbers, we found no significant excess in dN/dz towards FSRQ compared to SSRQ sightlines. (ii) The dN/dbeta distribution of Mg II absorbers along FSRQs and SSRQs are statistically similar. (iii) The cumulative distribution of weak Mg II absorbers is slightly lower for beta < 0.3, but shows an excess at higher beta. This suggests that, while intrinsic Mg II absorber abundance is comparable along both sightlines, FSRQs' more aligned relativistic jets cluster weak absorbers at high beta, consistent with the scenario of jet-driven acceleration of smaller gas clumps.

We present observations of the accretion-powered X-ray pulsar (XRP) 4U 1907+09, conducted with the Imaging X-ray Polarimetry Explorer (IXPE) that delivers the first high-quality polarization measurements of this source. 4U 1907+09 was observed twice during its brightest periods close to the periastron. We observe a stronger polarization in the first observation, with the phase-averaged polarization degree (PD) of $6.0 \pm 1.6\%$ and polarization angle (PA) of $69^\circ \pm 8^\circ$. In contrast, the second observation provides weaker constraints on the polarimetric properties, with a PD=$2.2 \pm 1.6\%$ and a PA=$46^\circ \pm 23^\circ$, as determined from the spectral-polarimetric analysis. Combining the data from both observations results in a PD=$3.7 \pm 1.1\%$ and a PA=$63^\circ \pm 9^\circ$. We detect an energy-dependent PA in the phase-averaged analyses with a significance of 1.7 $\sigma$. In the phase-resolved analyses, we observe a potential PA rotation by approximately $90^\circ$ between adjacent energy bands (4--5 and 5--6 keV) within the single phase bin of 0.25--0.375. We also investigate the influence of short flares on the polarization properties of this source. The results suggest that flares do not significantly affect the energy-phase-dependent PA, implying that the pulsar's geometry remains stable during flare events.

Observational astronomy has undergone a significant transformation driven by large-scale surveys, such as the Panoramic Survey Telescope and Rapid Response System (Pan-STARRS) Survey, the Sloan Digital Sky Survey (SDSS), and the Gaia Mission. These programs yield large, complex datasets that pose significant challenges for conventional analysis methods, and as a result, many different machine learning techniques are being tested and deployed. We introduce a new approach to analyzing multiband photometry by using a long-short term memory autoencoder (LSTM-AE). This model views mean measurements of multicolor photometry as a sequence in wavelength in order to encode patterns present in the stars' spectral energy distributions (SEDs) into a two-dimensional latent space. We showcase this by using Pan-STARRS grizy mean magnitudes, and we use globular clusters, labels from SIMBAD, Gaia DR3 parallaxes, and PanSTARRS images to aid our analysis and understanding of the latent space. For 3,112,259 stars in an annulus around the North Galactic Cap, 99.51% have their full SED shape reconstructed--that is the absolute difference between the observed and the model predicted magnitude in every band--within five hundredths of a magnitude. We show that the model likely denoises photometric data, potentially improving the quality of measurements. Lastly, we show that the detection of rare stellar types can be performed by analyzing poorly reconstructed photometry.

New results of modeling the operation of the new SPHERE-3 Cherenkov telescope are presented. The telescope will be able to detect cosmic particles by direct and reflected Cherenkov light of the extensive air showers (EAS). Dual detection improves the accuracy of determining the parameters of the primary particle. The study is based on the data bank of distributions of the EAS Cherenkov light obtained on the Lomonosov-2 supercomputer. The accuracy of determining the energy and type of the primary particle from the reflected and direct flux of Cherenkov light is estimated.

The astrophysical sources responsible for the production of high energy neutrinos remain largely uncertain. The strongest associations suggest a correlation between neutrinos and active galactic nuclei (AGN). However, it is still unclear which specific regions and mechanisms of the accreting supermassive black hole (SMBH) are responsible for their production. In this paper we investigate the correlation between the positions of IceCat-1 neutrino events and a large, optically selected QSO catalog extracted from the Sloan Digital Sky Survey. Within this sample, we distinguish radio-quiet QSOs from flat-spectrum radio QSOs (FSRQs)based on radio emission data from the Cosmic Lens All Sky Survey (CLASS) catalog. While the associations between neutrino events and radio-quiet QSOs are consistent with being all random matches, FSRQs exhibit a moderately significant correlation (2.7 sigma) with neutrino positions. Additionally we observe that the distribution of minimum distances between neutrino events and FSRQs differs significantly for events at declinations above and below 20 deg. In particular, using the KS test, we find that the high-declination event distribution shows a strong deviation (4 sigma) from a random distribution. We interpret all these results as an indication that a large fraction (> 60%) of the neutrino events observed by IceCube could be produced by the FSRQ and that the emission mechanism is likely related to the relativistic jets rather than the "radio-quiet" (RQ) component of these sources, such as the accretion disk or corona.

Over the past 40 years the brightness variations of XX Tri, a single line RS CVn type binary system with a synchronized K-giant primary, has exceeded one magnitude in the V band. Although these changes are primarily caused by starspots, an additional activity-related mechanism may also be behind the long-term trend of overall brightness increase. By compiling the most complete photometric data set so far, we attempt to examine how the nature of seasonal-to-decadal changes can be linked to global magnetism. The long-term brightening of XX Tri was accompanied by a gradual increase in the effective temperature, which resulted in a blueing shift in the Herzsprung-Russell diagram. In the long term, a constant cycle of about 4 years is most strongly present in the entire data. Besides, we also found a modulation of about 11 years, and a slowly decreasing cycle of about 5.7-5.2 years. From the seasonal datasets we found that the most dominant rotation-related periods are scattered around the orbital period. From this we infer a solar-type surface differential rotation, although the surface shear is significantly smaller than that of the Sun. The 4-year cycle indicates flip-flop-like behavior: during this time, the 2-3 active longitudes usually present on the stellar surface are rearranged. The magnitude-range changes in the long term cannot be interpreted solely as changes in the number and size of spots; the unspotted brightness of XX Tri has also increased over the decades. This should alert users of photometric spot models to reconsider the basic concept of constant unspotted brightness in similar cases.

We present deep H$\alpha$ and [O III] images of the ejecta rich nebulosity associated with the suspected runaway and binary Wolf-Rayet star WR~71 (HD 143414). In H$\alpha$ emission, the nebula appears as a crescent shaped, broken ring of clumpy emission some $9' \times 13'$ in angular size centered to the south and west of the WR star. At a Gaia estimated distance of 4.27 kpc, the nebula has physical dimensions of $11 \times 16$ pc making it one of the larger known ejecta rich WR ring nebulae. Our [O III] image also show considerable surrounding faint nebulosity much of which may be unrelated to the WR star. A comparison of the nebula's optical appearance with that seen in WISE 22 $\mu$m data shows infrared coincidence with the nebula's brightest [O III] emission features. Deep H$\alpha$ and [O III] images like those presented here suggests that new and substantially deeper imaging reconnaissance of WR star nebulae compared to earlier surveys may lead to additional WR ring nebula detections, thereby enhancing our understanding on the frequency and formation of WR ring nebulae.

Discrepancies between distance measurements and $\Lambda$CDM predictions reveal notable features in the distance-redshift relation, possibly suggesting the presence of an evolving dark energy component. Given the central role of the Friedmann-Lemaître-Robertson-Walker (FLRW) metric in modeling cosmological distances, we investigate here whether these features instead point to a possible departure from the fundamental FLRW symmetries. Exploiting the transverse and line-of-sight distances provided by baryonic acoustic oscillations (BAO) observations, we demonstrate that observed distances hint at a slight but systematic preference for an anisotropic expansion rate emerging regardless of the dark energy model considered. Leveraging this non-FLRW feature, we investigate an inhomogeneous extension of the $\Lambda$CDM model that naturally provides an anisotropic expansion rate. Our analysis demonstrates that models featuring spherical overdensities can explain BAO, supernova, and cosmic microwave background data, providing fits statistically indistinguishable from those obtained with a phantom dark energy scenario. When Pantheon+ data is considered, our analysis challenges the FLRW framework at $2.8\sigma$ and yields scenarios that can be interpreted as subtle but non-negligible deviations from the FLRW metric. When DESY5 supernovae are considered instead, deviations are notably more significant, yielding scenarios that mildly violate the Copernican principle and exclude the FLRW assumption at $5.2\sigma$. Overall, our results motivate a more in-depth investigation of whether the perfectly homogeneous and isotropic FLRW paradigm can still be assumed to accurately predict cosmological distances in the era of precision cosmology.

In this paper, we explore the use of a variational autoencoder (VAE), a deep generative model, to compress and generate images of dark matter density fields from $\Lambda$CDM like cosmological simulations. The VAE learns a compact, low-dimensional representation of the large-scale structure, enabling both accurate reconstruction and generation of statistically realistic samples. We evaluated the generated images by comparing their power spectra to those of real simulations and the theoretical $\Lambda$CDM prediction, finding strong agreement with the state-of-the-art simulations. In addition, the VAE provides a fast and scalable method for generating synthetic cosmological data, making it a valuable tool for data augmentation. These capabilities can accelerate the development and training of more advanced machine learning models for cosmological analysis, particularly in scenarios where large-scale simulations are computationally expensive. Our results highlight the potential for generative artificial intelligence as a practical bridge between physical modeling and modern deep learning in cosmology.

The process of bar formation, evolution and destruction is still a controversial topic regarding galaxy dynamics. Numerical simulations show that these phenomena strongly depend on physical and numerical parameters. In this work, we study the combined influence of the softening parameter, $\epsilon$ and disc mass fraction, $m_{\mathrm{d}}$ on the formation and evolution of bars in isolated disc-halo models via $N$-body simulations with different particle resolutions. Previous studies indicate that the bar strength depends on $m_{\mathrm{d}}$ as $\propto m_{\mathrm{d}}^{-1}$, which is seen as a delay in bar formation. However, the distorsion parameter, $\eta$, which measures the bar's momentum through time, shows that an increase in $m_{\mathrm{d}}$ does not always induce a delay in bar formation. This suggests that $\epsilon$ interact to either enhance or weaken the bar. Moreover, numerical heating dominates in models with small softening values, creating highly accelerated particles at the centre of discs, regardless of $m_{\mathrm{d}}$ or resolution. These enhanced particle accelerations produce chaotic orbits for $\epsilon \leq 5\,$pc, resulting in bar suppression due to collisional dynamics in the centre. In our high resolution models ($N \approx 10^{7}$), small softening values are incapable of reproducing the bar instability. The role of disc mass is as follows: increasing $m_{\mathrm{d}}$ for moderate $\epsilon$ ($\geq 10\,$pc) reduces the amount of drift in the acceleration profile, without affecting the bar's behaviour. Models with lower $m_{\mathrm{d}}$ values coupled with small softening values, have an excess of highly accelerated particles, introducing unwanted effects into otherwise reliable simulations. Finally, we show that the evolution of the disc's vertical acceleration profile is a reliable indicator of numerical heating introduced by $\epsilon$ and the bar.

The X-Ray Imaging and Spectroscopy Mission (XRISM) is the seventh Japanese X-ray observatory whose development and operation are in collaboration with universities and research institutes in Japan, the United States, and Europe, including JAXA, NASA, and ESA. The telemetry data downlinked from the satellite are reduced to scientific products using pre-pipeline (PPL) and pipeline (PL) software running on standard Linux virtual machines (VMs) for the JAXA and NASA sides, respectively. OBSIDs identified the observations, and we had 80 and 161 OBSIDs to be reprocessed at the end of the commissioning period and performance verification and calibration period, respectively. The combination of the containerized PPL utilizing Singularity of a container platform running on the JAXA's "TOKI-RURI" high-performance computing (HPC) system and working disk images formatted to ext3 accomplished a 33x speedup in PPL tasks over our regular VM. Herein, we briefly describe the data processing in XRISM and our porting strategies for PPL in the HPC environment.

The MeerKAT Fornax Survey is conducting a thorough examinationof the nearby Fornax galaxy cluster to understand how galaxies lose their cold gas and stop forming stars in low-mass clusters (M$_{\rm vir} \leq 10^{14}$ M$_\odot$). We are doing so through very deep (down to $\sim 10^{18}$ cm$^{-2}$) and high resolution (up to$\sim~ 1$ kpc and 1 km s$^{-1}$) MeerKAT observations of neutral atomic hydrogen gas (HI) in a $1\times2$ Mpc$^2$ region centred on Fornax. At the time of writing, the survey is $88\%$ complete. Initial analysis of the cluster's central area has unveiled the widespread existence of previously unseen HI tails and clouds. Some of the HI is clearly being removed from Fornax galaxies as they interact with one another or with the intra-cluster medium. We present a sample of galaxies with long, one-sided, star-less HI tails (of which only one was previously known) radially oriented within the cluster. The properties of these tails represent the first conclusive evidence that ram pressure is a key force shaping the distribution of HI in the Fornax cluster. Furthermore, interactions within the Fornax environment shape the HI mass function, the HI content of dwarf galaxies and determines how the HI sustains the nuclear activity of some cluster members and neighbouring galaxies.

The high-precision and long-duration photometry provided by the $Kepler$ mission has greatly advanced frequency analyses of a large number of pulsating stars, a fundamental step in asteroseismology. For $\delta$ Scuti stars, analyses are typically confined to frequencies below the Nyquist frequency. However, signals above this limit can be reflected into the sub-Nyquist range, especially in long-cadence data, where they may overlap with genuine pulsation modes and lead to misinterpretation. To address this issue, a recently proposed method -- the sliding Lomb-Scargle periodogram (sLSP) -- can effectively distinguish real frequencies from aliased ones. In this study, we compiled a sample of 68 $\delta$ Scuti stars whose frequency analyses were based on the $Kepler$ photometry. Using the sLSP method, we systematically examined the 1,406 reported frequencies in the literature. As a result, we identified 6 previously unrecognized reflected super-Nyquist frequencies in four stars: KIC 3440495, KIC 5709664, KIC 7368103, and KIC 9204718. We have once again demonstrated the ability of the sLSP method to detect and correct such artifacts. This technique improves the reliability of frequency selection, thereby enhancing the accuracy of asteroseismic interpretation and stellar modeling for the pulsating stars.

Determining cosmological parameters with high precision, as well as resolving current tensions in their values derived from low and high redshift probes, is one of the main objectives of the new generation of cosmological surveys. The combination of complementary probes in terms of parameter degeneracies and systematics is key to achieving these ambitious scientific goals. In this context, determining the optimal survey configuration for an analysis that combines galaxy clustering, weak lensing, and galaxy-galaxy lensing, the so-called 3x2pt analysis, remains an open problem. In this paper, we present an efficient and flexible end-to-end pipeline to optimise the sample selection for 3x2pt analyses in an automated way. Our pipeline is articulated in two main steps: we first consider a self-organising map to determine the photometric redshifts of a simulated galaxy sample. As a proof of method for stage-IV surveys, we use samples from the DESC Data Challenge 2 catalogue. This allows us to classify galaxies into tomographic bins based on their colour phenotype clustering. We then explore different redshift-bin edge configurations for weak lensing only as well as 3x2pt analyses in a novel way. Our method explores multiple configurations of perturbed redshift-bin edges with respect to the fiducial case in an iterative manner. In particular, we sample tomographic configurations for the source and lens galaxies separately. We show that, using this method we quickly converge into an optimised configuration for different numbers of redshift bins and cosmologies. Our analysis demonstrates that for stage-IV surveys an optimal tomographic sample selection can increase the figure of merit of the dark energy (DE) equation of state by a factor of $\sim$2, comparable to an effective increase in survey area of $\sim$4 for non-optimal photometric survey analyses.

Fermi-type shear particle acceleration is a promising mechanism for sustaining ultra-relativistic particles along the kilo-parsec scale jets in Active Galactic Nuclei (AGNs). We explore the possibility of synchrotron-limited electron acceleration in mildly relativistic shearing flows and present numerical solutions to the corresponding particle transport equation. We compare our findings with analytical calculations to infer an effective electron cutoff energy, and discuss the relationship to a simplified box model treatment. The results show that mildly relativistic large-scale jets offer a suitable environment for distributed electron acceleration beyond Lorentz factors of $\gamma_e \sim 10^8$.

We aim to construct a comprehensive global multi-scale kinematic equilibrium radiative-transfer model for the pre-transitional disc of DoAr 44 (Haro 1-16, V2062 Oph) in the Ophiuchus star-forming region. This model integrates diverse observational datasets to describe the system, spanning from the accretion region to the outer disc. Our analysis utilises a large set of observational data, including ALMA continuum complex visibilities, VLTI/GRAVITY continuum squared visibilities, closure phases, and triple products, as well as VLT/UVES and VLT/X-shooter H-alpha spectra. Additionally, we incorporated absolute flux measurements from ground-based optical observatories, Spitzer, IRAS, the Submillimeter Array, the IRAM, or the ATCA radio telescopes. These data sets were used to constrain the structure and kinematics of the object through radiative-transfer modelling. Our model reveals that the spectral line profiles are best explained by an optically thin spherical inflow/outflow within the co-rotation radius of the star, exhibiting velocities exceeding 380 km/s. The VLTI near-infrared interferometric observations are consistent with an inner disc extending from 0.1 to 0.2 au. The ALMA sub-millimetre observations indicate a dust ring located between 36 and 56 au, probably related to the CO2 condensation line. The global density and temperature profiles derived from our model provide insight into an intermediate disc, located in the terrestrial planet-forming zone, which has not yet been spatially resolved.

The study of pulsar glitches provides a unique window into the internal structure and dynamic processes of neutron stars. PSR J0007+7303, a very bright gamma-ray pulsar, is the first pulsar discovered by the Fermi-LAT telescope. In this paper, we present the 15 years of timing results of this pulsar using the Fermi-LAT data. We identified nine glitches, five of which are newly discovered. Among these, two are small glitches, occurring between the three previously reported ones, while the other four are large glitches. The glitches exhibit fractional frequency changes ranging from 15 x 10^-9 to 1238 x 10^-9, with intervals of approximately 1-2 years between events. Uniquely, this pulsar shows no exponential recovery behavior following any glitch, setting it apart from most glitching pulsars. Furthermore, no significant changes were observed in the gamma-ray pulse profile, flux, or phase-averaged spectra before and after glitches, indicating the stability of the pulsar's emission properties despite internal changes. A parametric analysis of the glitches yielded a fractional moment of inertia of the crustal superfluid involved in glitches as 1.06 percent, which matches extremely well with previous statistical work if the non-dissipative entrainment effect is not considered and strongly supports the internal origin of these glitches. These results highlight the distinct glitch behavior of PSR J0007+7303 and offer valuable insights into the crust-superfluid interaction in neutron stars. The physical origin of no exponential recovery is also discussed.

Diffuse non-thermal (NT) emission from the central starburst (CSB) of M82 has been measured at radio, X-ray and gamma-ray energies. Far-infrared (FIR), radio, and X-ray emission maps are mutually consistent, with radio and X-ray emissions spectrally similar - suggesting the latter to be Compton/FIR radiation. We present our analysis of 16.3 years of Fermi-LAT measurements, which - combined with newly-published VERITAS data - constitute the deepest, most extensive currently available gamma-ray dataset on M82. We model the NT radio to gamma-ray emission of the CSB as due to relativistic particles (CR). Key features of our models are the identification of the >50 GeV emission as pionic and the use of X-ray and radio emission to calibrate the CRe spectrum. This enables determination of the zero-point and slope of the CRp (and secondary CRe) spectrum, and meaningful estimates of the energy densities of CR and magnetic fields. We consider all relevant radiative processes involving CR, and use published detailed descriptions of the soft radiation fields in the CSB region - the most important of which is the FIR field, modeled as a graybody. Our SED modeling indicates that 1) the >10 GeV emission is mostly pionic, 2) the 0.1 < E/GeV < 10 emission is a combination of pionic and Compton/starlight (and subdominant NT bremss), 3) the <0.1 GeV gamma-ray emission is leptonic, and 4) the radio spectrum arises from primary and secondary CRe synchrotron at comparable levels: the corresponding CRe populations are described by a PL and a curved spectrum, respectively. Averaged over the FIR graybody models, the CRp spectral index and energy density are 2.3 and 385 eV/cm3 (for n(H) = 200 1/cm3), the primary-CRe and CRp maximum energies are 30 GeV and 7 TeV, and the magnetic field is B = 120 uG. The derived CR and B energy densities are in equipartition.

We analyze the influence of hyperons in binary neutron star mergers considering several different equations of state that include hyperons. By running a large set of simulations, we study the impact of the thermally produced hyperons on the gravitational-wave spectral features, the temperature evolution of the remnant, the mass ejecta and the threshold mass for prompt collapse to a black hole. Models with hyperons tend to stand out in the relation between the dominant postmerger gravitational-wave frequency and the tidal deformability of massive stars. Moreover, the averaged temperature of the remnant is reduced for hyperonic models. The mass ejection of the mergers is tentatively enhanced when hyperons are present in comparison to nucleonic EoSs leading to similar stellar properties of cold neutron stars, whereas the threshold mass for prompt black-hole formation is reduced by about 0.05~$M_\odot$ compared to the nucleonic models.

The orbital regime of a terrestrial planet plays a significant role in shaping its atmospheric dynamics, climate, and hence potential habitability. The orbit is also likely to play a role in shaping the response of a planetary atmosphere to the influx of material from an icy cometary impact. To investigate this response, we model the impact of an icy cometary body with an Earth-analogue exoplanet (i.e. an Earth-like planet orbiting a Sun-like star with a diurnal cycle) using a cometary impact and breakup model coupled with the 3D Earth-System-Model WACCM6/CESM2. To quantify the role that the atmospheric dynamics play in setting the response to a cometary impact, we compare our results with a previous study investigating an impact with a tidally-locked terrestrial exoplanet. We find that the circulation regime of the planet plays a key role in shaping the response of the atmosphere to an icy cometary impact. The weak, multi-celled circulation structure that forms on Earth-like planets is efficient at mixing material horizontally but not vertically, limiting the transport of water from the deep break-up site to higher altitudes. In turn, this limits the rate of water photodissociation at low pressures, reducing the magnitude of post-impact changes to composition. It also reduces the potential observability of an impact due to weakened cloud ice formation, and hence scattering, at low pressures. Despite this, small changes to the overall composition of the planet persist to quasi-steady-state, reinforcing the idea that ongoing bombardment may help to shape the composition/habitability of terrestrial worlds.

Short gamma-ray bursts are expected to be associated with compact object mergers, such as binary neutron star or neutron star-black hole systems, and are key high-energy multimessenger events. The detection of GRB 170817A, coinciding with the gravitational wave signal GW170817 from a BNS merger, confirmed the link between sGRBs and compact object mergers. Similarly, GRB 150101B displayed remarkable similarities to GRB 170817A, further supporting its association with compact binary mergers. The objective of this study is to uncover the intrinsic properties that differentiate merger-associated sGRBs from other GRBs by analyzing the Fermi GBM Burst Catalog and using GRB 170817A and GRB 150101B as reference events, enhancing our ability to select events from this class and promptly to search for their electromagnetic counterpart. We employed a clustering technique to classify GRBs based on their observed properties in gamma-rays (T90, Epeak and fluence). Prior to clustering, we tested three dimensionality reduction techniques, among which Uniform Manifold Approximation and Projection demonstrated the best performance making it the preferred technique for our analysis. This combination of dimensionality reduction and clustering analysis allowed us to group GRBs with similar characteristics, with a focus on identifying those most likely associated with BNS mergers. Our analysis successfully identified a cluster of sGRBs events with characteristics consistent with sGRB merger-associated. A comparison between our sample of candidates and known kilonova candidates associated with sGRBs, identified through other methodologies, further validated our approach.

Recent results from DESI BAO measurements, together with Planck CMB and Pantheon+ data, suggest that there may be a `phantom' phase ($w_{\rm de}<-1$) in the expansion of the Universe. This inference follows when the $w_0, w_a$ parametrization for the dark energy equation of state $w_{\rm de}$ is used to fit the data. Since phantom dark energy in general relativity is unphysical, we investigate the possibility that the phantom behaviour is not intrinsic, but effective -- due to a non-gravitational interaction between dark matter and non-phantom dark energy. To this end, we assume a physically motivated thawing quintessence-like form of the intrinsic dark energy equation of state $w_{\rm de}$. Then we use a $w_0, w_a$ model for the \emph{effective} equation of state of dark energy. We find that the data favours a phantom crossing for the effective dark energy, but only at low significance. The intrinsic equation of state of dark energy is non-phantom, without imposing any non-phantom priors. A nonzero interaction is favoured at more than $3\sigma$ at $z\sim0.3$. The energy flows from dark matter to dark energy at early times and reverses at later times.

A giant planet embedded in a protoplanetary disk excites spiral density waves, which steepen into shocks as they propagate away from the planet. These shocks lead to secular disk heating and gap opening, both of which can have important implications for the evolution of solids near the planet. To date, these two effects have largely been modeled independently. In this study, we present a self-consistent model that unifies these processes by linking shock heating and angular momentum deposition through the entropy jumps across the spiral shocks. We show that the model accurately reproduces the temperature and surface density profiles around the planet's orbit, as obtained from two-dimensional hydrodynamic simulations with standard $\alpha$ viscosity and $\beta$ thermal relaxation prescriptions. Furthermore, by incorporating an empirically derived scaling law for the radial distribution of the entropy jump, we construct a fully analytic model that self-consistently predicts the temperature and surface density structures of disks hosting a giant planet. This work represents a first step toward understanding how early-formed giant planets influence the formation of second-generation planets and planetesimals in their vicinity.

This paper examines the reliability of the Tremaine-Weinberg (TW) method in measuring the pattern speed of barred galaxies at high redshifts. Measuring pattern speeds at high redshift may help to shed light on the time evolution of interactions between galactic bars and dark matter halos. The TW method has been extensively employed for nearby galaxies, and its accuracy in determining bar pattern speeds has been validated through numerical simulations. For nearby galaxies, the method yields acceptable results when the inclination angle of the galaxy and the position angle of the bar fall within appropriate ranges. However, the application of the TW method to high-redshift galaxies remains unexplored in both observations and simulations. In this study, we generate mock observations of barred galaxies from the TNG50 cosmological simulation. These simulated observations are tailored to mimic the Integral Field Unit (IFU) spectroscopy data that the Near-Infrared Spectrograph (NIRSpec) on the James Webb Space Telescope (JWST) would capture at a redshift of $z\simeq 1.2$. By applying the TW method to these mock observations and comparing the results with the known pattern speeds, we demonstrate that the TW method performs adequately for barred galaxies with bars sufficiently long to be detected by JWST at high redshifts. This work opens a new avenue for applying the TW method to investigate the properties of high-redshift barred galaxies.

PyKOALA is an innovative Python-based library designed to provide a robust and flexible framework for Integral Field Spectroscopy (IFS) data reduction. By addressing the complexities of transforming raw measurements into scientifically valuable spectra, PyKOALA simplifies the data reduction pipeline while remaining instrument-agnostic and user-friendly. This proceeding outlines the challenges of IFS data reduction, PyKOALA's architecture, and its applications to observations by the KOALA+AAOmega instruments at the Anglo-Australian Telescope.

Galaxy interactions can disturb gas in galactic discs, compress it, excite it, and enhance star formation. An intriguing system likely consisting of two interacting galaxies overlapping on the line-of-sight was previously studied through ionised gas observations from the integral-field spectrograph Mapping Nearby Galaxies at APO (MaNGA). A decomposition into two components using MaNGA spectra, together with a multi-wavelength study, allowed to characterise the system as a minor-merger with interaction-induced star-formation, and maybe AGN activity. We use new interferometric observations of the CO(1-0) gas of this system from the NOrthern Extended Millimeter Array (NOEMA) to confront and combine the spatially-resolved ionised and molecular gas observations. Mock NOEMA and MaNGA data are computed from simulated systems of two discs and compared to the observations. The NOEMA observations of the molecular gas, dynamically colder than the ionised gas, help to precise the configuration of the system, which we revisit as being a major merger. Combination of ionised and molecular gas data allow us to study the star-formation efficiency of the system.

Quasi-periodic oscillations (QPOs) are observed in the hard state of many black hole X-ray binaries. Although their origin is unknown, they are strongly associated with the corona, of which the geometry is also subject to discussion. We present a thorough spectral-timing analysis of QPOs and broadband noise in the high-inclination BHXRB MAXI J1820+070, using the rich NICER data set of the source in the bright hard state of its outburst in 2018. We find that there is a large QPO hard lag between soft energy bands with significant disc emission and harder coronal power-law bands, which is absent when measuring lags between energy bands dominated by the coronal emission. The QPO lags between a soft band (with significant disc emission) and harder coronal power-law bands vary significantly with power-law flux, on time-scales of (tens of) seconds or a few QPO cycles, especially at QPO frequencies $\lesssim0.3$ Hz. At the same time, the QPO is found to be related to a decreased coherence between energy bands with significant disc emission and harder bands both at and below the QPO frequency, suggesting the QPO mechanism filters out part of the variability. Similar patterns in the frequency-dependent lags and coherence are observed in the BHXRB MAXI J1803-298, which is a (dipping) high-inclination source, but not in the low-inclination source GX 339-4. We suggest that these findings may be evidence of changes in the vertical extent of the corona on time-scales slightly longer than the QPO cycle.

Neutron stars emitting continuous gravitational waves may be regarded as gravitational pulsars, in the sense that it could be possible to track the evolution of their rotational period with long-baseline observations of next-generation gravitational wave interferometers. Assuming that the pulsar's electromagnetic signal is tracked and allows us to monitor the pulsar's spin evolution, we provide a physical interpretation of the possible observed correlation between this timing solution and its gravitational counterpart, if the system is also detected in gravitational waves. In particular, we show that next-generation detectors, such as the Einstein Telescope, could have the sensitivity to discern different models for the coupling between the superfluid and normal components of the neutron star and constrain the origin of timing noise (whether due to magnetospheric or internal processes). Observational confirmation of one of the proposed scenarios would therefore provide valuable information on the physics of gravitational wave emission from pulsars.

Markarian 421 (Mrk 421) is the closest and one of the brightest high-frequency peaked blazars, located at a redshift of z = 0.031. It is a strong source of gamma rays, and its broadband emission has been extensively studied over the years through multi-wavelength observations from various telescopes. Mrk 421 has been a target of observational campaigns conducted by the SST-1M telescopes - two single-mirror small-size Cherenkov telescopes at Ondrejov Observatory, Prague, Czech Republic. These telescopes operate in mono and stereoscopic modes, utilizing the Imaging Atmospheric Cherenkov Technique (IACT) to detect Very High Energy (VHE) gamma rays in the 1-300 TeV energy range. We present recent SST-1M observations, data analysis, and the results of preliminary physical modeling of Mrk 421's emission mechanisms.

Polar mesospheric clouds provide clues to physicochemical processes in the mesosphere and lower thermosphere. However, the heterogeneous nucleation and growth processes of water ice under polar mesospheric conditions are poorly understood, especially at the nanoscale. This study used reflection high energy electron diffraction and infrared reflection absorption spectroscopy to analyze the structure of vapor-deposited ice at polar mesospheric temperature (120 K) under vapor pressure conditions. The ice appeared to grow in three steps during vapor deposition, being amorphous water for the first 15 nm, then cubic ice up to 50 nm, and finally hexagonal ice subsequently. This three step growth suggests that the three observed phases can coexist in polar mesospheric clouds, depending on the thickness of water ice. The finding of the three-step growth also shows that the Ostwald rule of stages can hold for vapor deposited ice at low temperature.

Solar activity can be witnessed in the form of sunspots and active regions, where the magnetic field is enhanced by up to a factor 1000 as compared to that of the quiet Sun. In addition, solar activity manifests itself in terms of flares, jets, coronal mass ejections, and production of highly energetic particles. All these processes are governed by the solar magnetic field. Here we study the spatial reach of the influence of the magnetic field of active regions on the photosphere and in the solar corona. An active region is modelled by a magnetic dipole located under the photosphere. This simplified description allows us to study the spatial influence of an active region in the solar atmosphere in a rough but easy way. We find that the area of influence of the magnetic field of an active region on the solar atmosphere increases with, both, the maximum strength of the magnetic field in the active region and the depth of the dipole under the photosphere. For a typical active region, the magnetic field can be neglected for distances beyond ca. 700 Mm on the photosphere and two solar radii in the solar corona.

The IceCube Upgrade Camera System is a novel calibration system designed to calibrate the IceCube detector by measuring the optical properties of the Antarctic ice. The system comprises nearly 2,000 cameras and illumination LEDs, which are present on every D-Egg and mDOM, the newly designed optical modules for the IceCube Upgrade. These units, deployed across the IceCube Upgrade volume, will capture transmission and reflection images that can be used to characterize the optical properties of both the refrozen ice within drill holes and the bulk ice between strings. Additionally, the images can aid in determining the positions of the optical modules the camera systems are mounted on. To maximize the systems performance, various image analysis methodologies have been explored, ranging from classical maximum likelihood estimation to AI-based approaches using neural networks. In this study, we present preliminary results on the performance of these methods based on images generated by a simulation tool developed specifically for this system.

The Effective Field Theory (EFT) of Dark Energy (DE) is a model independent framework that allows for the description of a wide class of dark energy and modified gravity models. This is achieved by extending the Hilbert Einstein action through the introduction of time dependent functions. However, the choice of these functions and thus the operator basis is not unique. In this paper, we propose a physically motivated constraint based on the continuity equation, leading to a continuity equation compatible (CEC) basis that ensures a clear physical interpretation of the background EFT operators.

SN\,2025kg, linked to EP250108a, is among the brightest broad-lined Type Ic supernova (SN Ic-BL) known, showing unique helium absorptions, a late-time broad H$\alpha$, and an early bump. In this {\em{Letter}}, we propose a jet-cocoon origin to explain EP250108a as off-axis cooling emission from a mildly relativistic inner cocoon viewed at $\sim45^\circ$ and the early bump of SN\,2025kg as the outer cocoon cooling emission, both constraining an energy of $\sim(1-2)\times10^{52}{\rm{erg}}$ and a progenitor radius of $\sim5\,R_\odot$. To explain SN\,2025kg's exceptionally luminous peak, potential energy injection into the $\sim2.5\,M_\odot$ ejecta from a magnetar with initial period $\sim1.7\,{\rm{ms}}$ and magnetic field $\sim2\times10^{15}{\rm{G}}$ may be required, implying a rapidly rotating $\sim4\,M_\odot$ progenitor. Thus, the progenitor may be a low-mass helium star with an extended helium envelope, supported by helium absorption lines and an inferred weak pre-SN wind. Hydrogen-rich material may reside in the inner ejecta layers, as suggested by the late-time broad H$\alpha$, possibly originating from main-sequence companion material evaporated by the magnetar wind. Since the observed near-solar metallicity challenges the popular quasi-chemically homogeneous evolution channel, the rapidly rotating helium-star progenitor of EP250108a/SN\,2025kg might attain angular momentum by being tidally spun up by a main-sequence companion in a close binary formed through isolated binary evolution.

We present compelling observational evidence supporting G178.28-00.61 as an early-stage candidate for Cloud-Cloud Collision (CCC), with indications of the formation of an S-shaped filament, evenly-separated dense cores, and young star clusters. The observations of CO molecular line emission demonstrate the existence of two interacting molecular clouds with systemic velocities of 0.8 km/s and -1.2 km/s, respectively. The convergence zone of these two clouds reveals an S-shaped filament in the JCMT 850 micron continuum image, suggesting cloud interaction. In line with expectations from CCC simulations, broad bridging features are discernible in the position-velocity diagrams. An elevated concentration of identified Class I and II young stellar objects along the filament at the intersection area further supports the hypothesis of a collision-induced origin. This observation could be explained by a recent MHD model of CCC (Kong et al. 2024), which predicts a similar morphology, scale, density, and unbound status, as well as the orientation of the polarization.

We investigate the influence of large-scale cosmic web environments on galaxy quenching using a volume-limited, stellar mass-matched galaxy sample from SDSS DR18. Galaxies are classified as residing in sheets, filaments, or clusters based on the eigenvalues of the tidal tensor derived from the smoothed density field. The quenched fraction increases with stellar mass and is highest in clusters, intermediate in filaments, and lowest in sheets, reflecting the increasing efficiency of environmental quenching with density. A flattening of the quenched fraction beyond $\log_{10}(M_\star/M_\odot) \sim 10.6$ across all environments signals a transition from environment-driven to mass-driven quenching. In contrast, the bulge fraction continues to rise beyond this threshold, indicating a decoupling between star formation suppression and morphological transformation. At the high-mass end ($\log_{10}(M_\star/M_\odot) \gtrsim 11.5$), both quenched and bulge fractions bifurcate, increasing in clusters but declining in sheets, suggesting a divergent evolutionary pathway where massive galaxies in sheets retain cold gas and disk-like morphologies, potentially sustaining or rejuvenating star formation. The AGN fraction also increases with stellar mass and is somewhat higher in sheets than in clusters, indicating enhanced AGN activity in low-density, gas-rich environments. The high-mass trends are independently corroborated by our analysis of specific star formation rate, $(u-r)$ colour, concentration index, and D4000 in the stellar mass-density plane, which show that massive galaxies in sheets remain bluer, younger, more star-forming, and structurally less evolved than their cluster counterparts. Our results highlight the cosmic web as an active driver of galaxy evolution.

We explore how recent advances in the manipulation of single-ion wave packets open new avenues for detecting weak magnetic fields sourced by ultralight dark matter. A trapped ion in a ``Schrödinger cat'' state can be prepared with its spin and motional degrees of freedom entangled and be used as a matter-wave interferometer that is sensitive to the Aharonov-Bohm-like phase shift accumulated by the ion over its trajectory. The result of the spin-motion entanglement is a parametrically-enhanced sensitivity to weak magnetic fields as compared with an un-entangled ion in a trap. Taking into account the relevant boundary conditions, we demonstrate that a single trapped ion can probe unexplored regions of kinetically-mixed dark-photon dark matter parameter space in the $10^{-15}~\text{eV} \lesssim m_{A'} \lesssim 10^{-14}$~eV mass window. We also show how such a table-top quantum device will also serve as a complementary probe of axion-like particle dark matter in the same mass window.

Sterile neutrinos produced in the early Universe that mix with active neutrinos of the Standard Model are typically considered to consist of a single population resulting from one dominant production mechanism. We show that the same sterile neutrino species can naturally emerge with multiple population components, yielding a multi-modal relic momentum spectrum. We consider this with four distinct production scenarios: active-sterile non-resonant oscillations following resonant oscillations in the presence of a primordial lepton asymmetry, gravitational production through sterile neutrinogenesis from populations of evaporating primordial black holes, and heavy singlet Higgs or inflaton decays combined with non-resonant active-sterile oscillations or neutrinogenesis. We identify sterile neutrino mass ranges where a colder and a hotter population can be present with similar contributions and can also contribute non-negligibly to the dark matter relic abundance. We discuss some potential consequences of such a multi-population framework.

Binary pulsars offer a unique natural laboratory to test General Relativity (GR) and probe for deviations from its paradigm, as predicted by alternative theories of gravity. In this paper, we study two such possible deviations: a time variation of Newton's constant $G$ and the emission of dipolar gravitational radiation. We use updated data for some well-known pulsars, namely PSR J1738+0333, PSR J1012+5307, and PSR J1713+0747, to extract the Keplerian and post-Keplerian parameters that characterize their orbital dynamics, using recent high-precision pulsar timing data and a Bayesian parameter estimation with Markov chain Monte Carlo (MCMC) techniques. We do this via the TEMPO2 software, the MCMC4Tempo2 plugin, and a unified python pipeline to analyze the data. We then perform a combined analysis of different binary systems to constrain both the time evolution of Newton's constant and the dipolar emission parameter $\kappa_D$. For the best of our three pulsars (PSR J1713+0747), we obtain $\dot{G}/G = (0.32 \pm 0.31) \times 10^{-12}~\text{yr}^{-1}$ at 95\% confidence, along with a stringent constraint on the dipolar emission parameter, $\kappa_D = (-0.04 \pm 0.14) \times 10^{-4}$. Thanks to the recent high-precision timing data sets, we provide updated bounds on key parameters relevant to modified gravity theories, and we find that our results are consistent with GR.

We consider phenomenological models for nonsingular black hole that satisfy the limiting curvature condition (i.e., that have curvatures that are always sub-Planckian in size) while having a more general dependence on the black hole mass than the most studied examples. These models allow black holes to exist while having regulators that are larger than the horizon scale; it has been shown previously that this can lead to observable consequences in an astrophysical setting, for allowed choices for the regulator scale. Noting that substantial horizon-scale modifications of the metric will affect black hole thermodynamics and Hawking radiation, we study these metrics in the context of primordial black hole dark matter. Considering examples with de\,Sitter and Minkowski cores, respectively, we study the effect of the regulator in these metrics on the allowed black hole mass ranges (or ``bands"), the black hole temperature, specific heat and lifetime, and the bounds on the primordial black hole fraction of the total dark matter density from the observed extragalactic gamma ray background.

Using only the standard considerations of spacetime foam and the Euclidean Quantum Gravity techniques known long ago, we result to a model of Topological Dark Energy (TDE) that outperforms the standard $\Lambda$CDM paradigm with regard to data fitting efficiency. Specifically, it is known that at the foam level, topologically non-trivial solutions such as instantons appear. In the particular case of Einstein-Gauss-Bonnet gravity, we obtain an effective dynamical dark energy term proportional to the instanton density, and the latter can be easily calculated through standard techniques. Hence, we can immediately extract the differential equation that determines the evolution of the topologically induced effective dark energy density. Significantly, this TDE scenario allows for changing sign of dark energy during the cosmic evolution and also exhibits Dark Energy interaction with Dark Matter. We confront the TDE scenario, in both flat and non-flat cases, with Pantheon+/SH0ES Supernovae Type Ia (SNIa), Baryonic Accoustic Oscillations (BAO), and Cosmic Chronometers (CC) datasets. By applying standard model selection methods (AIC and DevIC information criteria), we find a moderate but statistically significant preference over $\Lambda$CDM scenario. Finally, we show that the TDE scenario passes constraints from Big Bang Nucleosynthesis (BBN) and thus does not spoil the thermal history of the Universe.

Time-Delay Interferometry (TDI) is essential for space-based gravitational wave (GW) missions, as it suppresses laser frequency noise and achieve the required sensitivity. Beyond the standard Michelson configuration, a variety of second-generation TDI schemes have been proposed, each utilizing different combinations of inter-spacecraft laser links. In this work, we conduct a comparative study of several representative TDI configurations with varying time spans and demonstrate that their (quasi-)orthogonal channels are highly correlated, indicating substantial redundancy among these schemes. In the low-frequency regime, the performance of different TDI configurations are nearly identical. Their distinctions emerge primarily at high frequencies, where the GW wavelength becomes comparable to the arm length. In this regime, shorter TDI time spans with minimal null frequencies facilitate more accurate waveform modeling and parameter recovery in frequency domain. In contrast, configurations with longer time spans and more null frequencies, such as the Michelson, are more susceptible to frequency aliasing and waveform modulation effects, which degrade inference accuracy. However, if signal modeling and analysis are performed in the time domain, all TDI configurations become effectively equivalent. Considering the usability in both frequency and time domain, the short-span PD4L scheme, which exhibits minimal nulls and superior performance in high frequencies, emerges as a promising candidate for future space-based GW mission designs.

The Phase-Space Approximation (PSA) approach, originally applied in [Phys. Rev. D 106, 123006 (2022)] to describe neutrino oscillations from a stellar object in the two-flavor limit, is extended here to describe the more realistic case where neutrinos can oscillate between three different flavors. The approach is successfully validated against the exact solutions up to eight neutrinos. In all cases where the exact solution is feasible, the PSA provides excellent reproduction of the neutrino oscillation dynamics. By replacing the full problem with a set of simple mean-field equations, the PSA offers a versatile, predictive, and easily parallelizable approach for tackling three-flavor problems. This enables the simulation of large-scale neutrino oscillations, as illustrated here with simulations involving up to 300 neutrinos. Additionally, the method provides insight into the system's equilibration properties.

Astrometric missions like Gaia provide exceptionally precise measurements of stellar positions and proper motions. Gravitational waves traveling between the observer and distant stars can induce small, correlated shifts in these apparent positions, a phenomenon known as astrometric deflection. The precision and scale of astrometric datasets make them well-suited for searching for a stochastic gravitational wave background, whose signature appears in the two-point correlation function of the deflection field across the sky. Although Gaia achieves high accuracy in measuring angular separations in its focal plane, systematic uncertainties in the satellite's absolute orientation limit the precision of absolute position measurements. These orientation errors can be mitigated by focusing on relative angles between star pairs, which effectively cancel out common-mode orientation noise. In this work, we compute the astrometric response and the overlap reduction functions for this relative astrometry approach, correcting previous expressions presented in the literature. We use a Fisher matrix analysis to compare the sensitivity of relative astrometry to that of conventional absolute astrometry. Our analysis shows that while the relative method is theoretically sound, its sensitivity is limited for closely spaced star pairs within a single Gaia field of view. Pairs with large angular separations could provide competitive sensitivity, but are practically inaccessible due to Gaia's scanning law. Finally, we demonstrate that combining astrometric data with observations from pulsar timing arrays leads to slight improvements in sensitivity at frequencies greater than approximately 10^-7 Hz.