Papers for Wednesday, Apr 29 2026

Primordial magnetic fields (PMFs) enhance small-scale structure formation through the Lorentz force acting on baryons, boosting the abundance of low-mass halos and their hosted galaxies. We show that the reionisation history calibrated with the UV luminosity function (UVLF) provides stringent bounds: strong PMFs induce a characteristic double reionisation at $z \approx 24$ that is incompatible with CMB measurements of the optical depth, yielding $\sqrt{\left\langle B^2 \right\rangle} < 0.27\,{\rm nG}$ and $< 0.18\,{\rm nG}$ for $n_B = -2$ and $n_B = 2$ respectively at $95\%\,{\rm CL}$ using Planck priors on $\tau$. This establishes early galaxy observables as among the most sensitive probes of PMFs in Gaussian, non-helical scenarios.

The circumgalactic medium (CGM) is known to contain multiphase gas in various stages of evolution and interaction with the galaxy. In order to characterize its detailed behavior on short timescales, we use a subregion of the TNG100 cosmological simulation to study the evolution of the $z=1$ CGM around six galaxies in $10^{11.5}-10^{12}$ $M_{\odot}$ halos at a high time cadence of $\approx2$ Myr. We use Monte Carlo tracer particles to follow this CGM gas forward in time in a Lagrangian way and determine how its thermodynamic and kinematic properties change. We find that CGM gas mixes between different temperature and density phases quickly and within $\approx500$ Myr evolves into distinct cold ($T\approx10^4$ $\rm{K}$) and warm-hot ($T\approx10^{5.5}$ $\rm{K}$) phases at small and large distances from the galaxy, respectively, regardless of its initial ($z=1$) halo-centric radius. This is largely driven by feedback from the galaxy, which heats and ejects cold gas that had previously cooled and accreted toward and occasionally into the galaxy from the outer CGM. We see signatures of this process in autocorrelations of kinematic quantities, which take $\approx400$ Myr to fully decorrelate from their initial values, suggesting a timescale over which feedback disrupts and reprocesses CGM gas. We also examine gas in narrow temperature and density ranges associated with commonly observed ions and find that gas that is O VI-like stays in its phase for hundreds of Myr longer than gas that is Mg II-like or C IV-like, suggesting that CGM observations of different species could probe gas in different evolutionary states, even if the gas is cospatial.

Empirical models often rely on key relations from the galaxy--halo connection to construct mock galaxy catalogues. These relations typically describe central galaxies more accurately than satellite galaxies, which are generally less massive and orbit within larger haloes. Satellite galaxies are affected by a variety of physical processes that pose significant challenges for modelling. In this work, we use \MTNG, a state-of-the-art cosmological hydrodynamic simulation, to study the evolution of the baryonic component of satellites. Using the merger trees from this simulation, we follow the evolution of all $z=0$ satellite galaxies, tracking their stellar mass, gas mass, and $r$- and $U$-band magnitudes. We characterise this evolution using proxies including the fraction of subhalo mass and maximum circular velocity remaining relative to infall, the pericentric distance, and the time since infall. All of these quantities are commonly available in gravity-only simulations and can therefore be used to model these trends in simpler galaxy population models. We find that the gas mass, which is well described by the remaining subhalo mass fraction, declines much more rapidly than the other components, with satellites losing $\sim 80\%$ of their gas by the time the subhalo has lost half of its total mass. By contrast, the evolution of stellar mass and magnitudes is overall slower and is better described by the reduction of the host subhalo $v_{\rm max}$. We then examine the evolution of satellite mass profiles. We find that, although stripping is strongest in the outer regions, the intermediate and inner parts of satellites experience mass loss at early times. The results of this work can be used by empirical models and galaxy formation models built on gravity-only simulations to improve their descriptions of satellite galaxies.

We present spectroxide, a code package for computing cosmic microwave background spectral distortions in which all ${\sim}14{,}500$ lines of Rust code, Python interface, and ${\sim}400$ automated tests were written by an AI assistant (Claude Code) under human physicist supervision. The solver evolves the photon Boltzmann equation under Compton scattering, double Compton emission, and Bremsstrahlung from $z \sim 5 \times 10^6$ to the present, computing spectral distortions from arbitrary heat and photon injection within this redshift range. No fully open-source code of this kind is publicly available; we validate against analytic limits, published spectra, and publicly available precomputed Green's function tables. We document the development as a case study in AI-assisted scientific computing, highlighting how domain expertise caught physics bugs (incorrect dimensional prefactors, near-cancellation errors) that evaded the full automated test suite, and provide recommendations for best practices in human--AI collaborative development of scientific software. We make spectroxide publicly available on GitHub.

We present a forward-modeling framework for synthesizing Type Ia supernova (SN Ia) populations by coupling cosmological hydrodynamic simulations to binary population synthesis (BPS). Using IllustrisTNG star particles as simple stellar populations, we generate binaries and evolve them with COMPAS to produce synthetic SNe Ia tagged with explosion times and progenitor channels (single- and double-degenerate; SD and DD). This cosmology-BPS pipeline enables self-consistent, end-to-end tracking of SN Ia populations from individual galaxies to cosmic scales. The model reproduces key SN-related observables, including host-galaxy demographics, delay-time distributions (DTDs), SN-rate trends with host properties and redshift, and a progenitor-age 'step' implicated by the mass step in Hubble residuals. Our main findings are as follows. (1) Contrary to the standard assumption, DTDs appear intrinsically non-universal: their form depends on progenitor channel and metallicity, and thus varies systematically across hosts and with redshift. The commonly adopted DTD is therefore best regarded as a population-averaged approximation rather than a fundamental kernel. (2) We predict that the dominant SN Ia progenitor population shifts from SD to DD with cosmic time, with a demographic crossover near z = 0.5 (~5.2 Gyr ago). This non-monolithic SN Ia population with a redshift-dependent SD/DD mixture weakens the universality implicit in a single globally calibrated standardization. Taken together, evolution in both the DTD and the channel mixture can imprint redshift-dependent systematics on SN Ia luminosities, strengthening the case for jointly inferring progenitor/host-driven effects alongside cosmic acceleration. The full catalogue and analysis scripts are available via Zenodo.

Galaxy clusters grow through the matter accretion from the cosmic web, mainly along filaments. We aim to characterize the gas accretion onto clusters, focusing on the role of filaments in driving anisotropic inflows and thermodynamic properties, as it remains a key challenge for cosmology. In this study, we analyzed 415 galaxy clusters from the IllustrisTNG-300 hydrodynamical simulation at $z=0$. Anisotropic signatures are highlighted by probing both isotropically and anisotropically (gas in filaments only), the radial profiles of gas properties (including temperature, entropy, density, and pressure), and the radial velocity distributions. Our results highlight two distinct regimes of gas accretion depending on the cluster-centric distances. In the cluster environment ($\sim$ 2-4$R_{200}$), fast infalling warm gas tunneled by cosmic filaments enters the warm-hot circumcluster medium, but filaments remain colder due to their slow thermalization with the surrounding, generating transverse temperature gradients. At the cluster outskirts ($\sim$ 1-2$R_{200}$), gas infalling along filaments enters the hot intracluster medium, with a strong tangential velocity gradient. Warm gas tends to penetrate clusters from filaments, while hot gas is preferentially ejected beyond them. The mass and dynamical state of clusters significantly impact these accretion features, with relaxed and massive clusters exhibiting stronger and more extended temperature discontinuities. Overall, this work emphasizes a coherent picture of anisotropic gas accretion from filaments onto clusters. While virial shocks tend to be observed near the cluster boundary, especially at the filament-cluster interface. We do not find strong evidence of accretion shocks around filaments, suggesting slow thermalization of filament gas as it enters the dense warm-hot circum-cluster environment.

Most dwarf spheroidal (dSph) satellites of the Milky Way follow exponential surface density profiles that decline sharply in the outer regions. The Sculptor (Scl) and Ursa Minor (UMi) dSphs deviate from this trend and show a clear excess of stars in the outskirts. Individual members have recently been identified as far as ${\sim}10$ effective radii from the center in both systems. We study whether far-outlying stars in Scl and UMi may result from Galactic tidal forces using idealized N-body simulations. Our results indicate that, on their current orbits, neither galaxy has experienced tidal forces sufficient to affect its stellar density profile. The observed velocity dispersion and size of Scl and UMi imply the dwarfs are simply too dense to have been affected by Galactic tides. We also find weak tidal evolution when including the effects of the Large Magellanic Cloud, which our simulations suggest substantially perturbed Scl's orbit during a close encounter. Our results are insensitive to assumptions about the detailed dark matter density profile of either galaxy, including the presence of an inner core. We conclude that the outlying stars in Scl or UMi are not of tidal origin, but rather innate features that possibly reflect past merger events or the presence of multiple dynamical components.

Dwarf spheroidal galaxies (dSphs) are prime laboratories for studying dark matter (DM) and the black hole demographics in the low-mass regime. These systems are also often flattened; nevertheless most studies rely on spherical models, potentially affecting dynamical inferences. We introduce the first multi-component, axisymmetric dynamical models of dSphs based on distribution functions and apply them to the Milky Way dSphs Draco and Ursa Minor. The stellar distribution is described by chemo-dynamically distinct axisymmetric populations tracing a spherical potential generated by a dominant DM halo and a central intermediate-mass BH (IMBH). The models are fitted to discrete stellar data from a Gaia-based astrometric sample and two spectroscopic datasets providing line-of-sight velocities and metallicities, testing robustness across samples. We compare the DM properties under different modelling assumptions, including flattened one- and spherical two-component models. Both galaxies are better described by two stellar populations: a metal-rich, kinematically colder and concentrated component, and a more extended metal-poor one with hotter kinematics. We detect weak rotation, dynamically unimportant and ignored in the models. We measure a cuspy DM density profile in Draco ($\gamma=0.98_{-0.26}^{+0.28}$), and a more cored distribution ($\gamma=0.37_{-0.24}^{+0.31}$) for Ursa Minor. The DM halo of Draco remains stable across all models and datasets, making it the most robustly determined in the Local Group and highly relevant for indirect DM searches. We show that modelling flattened systems with spherical models can bias the DM inner slope towards cuspier values, while we find no degeneracy between inner halo density and inclination. We find no evidence for IMBHs and place upper limits on their masses, $\log M_{\rm BH}[M_{\odot}] < 5.2$ for Draco and $< 3.33$ for Ursa Minor (95% confidence).

In this paper we present the chemical screening of the stellar population belonging to the globular cluster NGC 6553 in the Galactic bulge. This study has been conducted in the contest of the Bulge Cluster Origin (BulCO) survey, an ESO-VLT Large Program currently ongoing with CRIRES in the NIR domain. This survey is performing an unprecedented chemical screening of 17 stellar systems orbiting the Milky Way bulge, with the aim of unveiling their origin and true nature. Here we present and discuss the abundances of 18 elements produced via distinct nucleosynthetic channels for 14 red giant branch stars belonging to NGC 6553. We found a mean [Fe/H] = -0.20 $\pm$ 0.01 dex, and about solar-scaled iron-peak elements, confirming that this is one of the most metal-rich globular clusters in the Milky Way. We also found [X/Fe] enhancement of $\alpha$ and several other light elements. Furthermore, we assess the presence of multiple populations typical of genuine globular clusters from the significant spreads in Na, N, and C, and an almost vertical Na-O anti-correlation. Finally, by using classical ([$\alpha$/Fe] vs [Fe/H]) and newly-defined ([V/Fe] and [Zn/Fe] vs [Fe/H]) "chemical DNA tests", we prove its in-situ formation within the Galactic bulge.

Dust growth is a crucial step in planet formation, and the efficiency of this process is controlled by the physical and chemical properties of the dust grains. Monte Carlo-based methods are commonly used to follow the collisional evolution of dust while tracking their properties. However, current Monte Carlo methods in planet formation do not strictly conserve the global inventory of dust properties across the protoplanetary disk, causing fluctuations that can grow over time and affect predictions of dust evolution. Here we present a coagulation algorithm that ensures the global conservation of dust properties while resolving the spatial evolution of dust. The method is validated against analytical solutions for standard coagulation kernels and benchmarked in a two-dimensional disk. We show that the method reproduces standard results, resolves the full dust population, and improves the resolution of the small-grain regime compared to other Monte Carlo methods for modeling global dust evolution. Finally, using a test case that includes sublimation and condensation of water interacting with silicates, we demonstrate strict conservation of each component's mass during coagulation, establishing the method as a valuable tool for tracking dust properties in protoplanetary disks.

We measure the influence of image augmentations and training dataset size when training a deep neural network to classify galaxy morphology. Data augmentation is an integral step when training machine learning models and often astronomers add augmentations assuming they will always improve the performance of their models. We train multiple versions of the same pre-existing Zoobot model using different image augmentations and different dataset sizes from 230,000 galaxy images from Galaxy Zoo DECaLS to determine whether this assumption is necessarily true. We find that generally, the addition of image augmentations does improve a deep neural network's performance, however, this improvement is significantly diminished as the training dataset size increases. The choice of specific augmentations (provided they are sensible) does not seem to be as important as simply having augmentations as different augmentations result in similar increases in performances. We find that for a model of a given size, there exists a saturation point (when the model's capacity has been filled with data) that cannot be surpassed with data augmentations. We find that more complex augmentations result in longer training times and might not lead to improved performance. If augmentations are added to the training process (which is recommended), simpler augmentations might be sufficient, depending on the size of the dataset and model. We therefore encourage astronomers to carefully consider their use of image augmentations in an effort to reduce wasted time and computational resources.

The impact of AGN feedback on the hot gas content of galaxy groups remains a key uncertainty in galaxy formation and its connection to the large scale structure of the Universe. We aim to compare the XMM-Newton Group AGN Project (X-GAP) sample to the hydrodynamical FLAMINGO simulations, which span a wide range of AGN feedback prescriptions. We construct X-GAP analogues by forward-modelling the full selection function, including detection and observational systematics, and generate end-to-end XMM-Newton mock observations analysed consistently with the data. We study multiple observables, including the L--T and Mgas--T relations, number of groups, mean temperature, and velocity dispersion, accounting for their covariance. The forward model accurately recovers input luminosities, gas masses, and core-excised temperatures for regular systems, enabling direct comparison in observable space. The normalisation of the scaling relations is the best discriminator between feedback models, while cosmic variance introduces > 20% fluctuations in the number of detected systems, making counts alone a weak discriminator. Models with intermediate feedback strength provide the best agreement with X-GAP, with the fgas-2sigma model yielding the lowest tension of only 0.8sigma, while the most extreme feedback scenario (fgas-8sigma) is ruled out at > 4sigma. Our results indicate that the thermodynamic properties of galaxy groups favour feedback stronger than the fiducial FLAMINGO calibration, but disfavour the most ejective models. This highlights the importance of combining forward modelling and multi-observable constraints to probe the fate of hot baryons in low-mass haloes.

Lunar gravitational-wave (GW) detectors relying on the measurement of the response of the Moon to GWs are susceptible to a seismic background, which might pose a fundamental sensitivity limitation. The Lunar Gravitational-wave Antenna (LGWA) was conceived as an array of accelerometers with the idea that data can be processed to distinguish between a GW signal and the seismic background. As a result, the seismic noise of the GW measurement would be mitigated. However, so far, no quantitative assessment of the mitigation of the seismic background has been provided. In this article, we derive the analytical expressions for the optimal squared signal-to-noise ratio considering two seismic stations in an isotropic, random, Gaussian seismic field. Our numerical analysis reveals that the capacity to mitigate the seismic noise critically depends on the distance between the two stations relative to the seismic-correlation length. We demonstrate that optimal placement of the two stations can yield significant improvements in the equivalent seismic noise amplitude spectrum density (ASD), approximately a factor of 2.3 at 0.3 Hz, compared to the measurement with a single station. The equivalent ASD of the seismic noise also exhibits distinct oscillatory and mitigation features arising from the Bessel-function structure of the noise correlation.

Context. The Gaia collaboration announced the discovery of a binary of a massive black hole (33 M$_\odot$) with a low-mass giant star (Gaia BH3) in the ED-2 stellar stream. The properties of this binary, as well as its position in the stream, challenge a formation scenario invoking only isolated binary evolution. Aims. We aim to quantify the importance of dynamics in the formation of Gaia BH3 in the progenitor cluster of the ED-2 stream. Methods. We perform detailed N-body simulations of the progenitor cluster of the ED-2 stream, including the effects of single and binary stellar evolution. We compare these simulations to observations of the ED-2 stream and the properties of Gaia BH3. Results. We determine that Gaia BH3 most likely formed as an exchange binary which underwent multiple strong dynamical interactions. We highlight the importance of cluster dynamics in assembling Gaia BH3, and disfavour a formation scenario where it evolved in isolation and/or in a low-density cluster. Conclusions. The role of dynamics should be considered when interpreting properties of star-black hole binaries found in the next Gaia Data Release.

We present a new multiband extension to the crowdsource photometric pipeline, enabling simultaneous fitting across multiple imaging bands in crowded fields. The core idea is that multiple images of the same part of the sky should have the same sources at the same locations; only the fluxes in the different images should be allowed to vary in fitting. The framework also allows us to use all images of a given region to detect faint sources, with configurable weighting among the different bandpasses as appropriate for different source spectra. Similar concepts are already present in other crowded field packages like DAOPHOT and DOLPHOT; we now include it in the crowdsource fitting approach. We describe the mathematical formulation of the multiband fit and demonstrate its performance using the Wide-field Infrared Survey Explorer (WISE) W1 and W2 imaging as a concrete application. The multiband algorithm improves flux consistency and reduces band-to-band positional scatter relative to independent-band fitting. We test the method on unWISE coadded tiles spanning both sparse and crowded regions and quantify improvements in photometric agreement and astrometric stability. This framework provides a general foundation for future multiband crowded-field catalogs.

We present a detailed study of the inner regions of NGC~7582, a nearby Seyfert~2 galaxy, from the Galaxy Activity, Torus and Outflow Survey (GATOS). The galaxy hosts a circumnuclear star-forming disk and an AGN-driven biconical ionised outflow. Using JWST NIRSpec and MIRI/MRS integral-field spectroscopy, we analyse ionic emission lines spanning a wide range of ionisation potentials (IPs, $\sim 8$--$126$ eV). Gaussian line-profile fitting reveals kinematic stratification: low-IP species ($\lesssim 20$ eV; e.g., [Fe II], [Ar II], [Ne II]) trace ordered disk rotation with PA $\sim -12 \pm 3^\circ$, while high-IP species ($\gtrsim 35$ eV; e.g., [O IV], [Mg IV], [Ne V]) follow the outflow with PA $\sim 54 \pm 10^\circ$. Outflowing gas exhibits systematically higher velocity dispersions ($119 \pm 13$ km/s) than the disk ($78 \pm 11$ km/s), consistent with turbulent or bulk motions. Intermediate-IP lines, [S III], [Ar III], and [Ne III], show contributions from both components, with the outflow characterised by higher dispersion, lower amplitude, and higher velocities in double-Gaussian fits. For these lines, a thin inclined disk plus one-dimensional outflow model enables robust separation and quantification of the disk and outflow velocity fields. The outflow is consistent with a hollow bicone capable of accelerating gas beyond the local escape velocity, implying most material is unlikely to be re-accreted. The ionisation cone opening angle shows no dependence on IP, indicating the AGN torus polar regions are largely unobscured. Our study provides new insights into AGN-driven outflows and circumnuclear disk dynamics, offering a framework to disentangle overlapping ISM kinematics in nearby active galaxies.

The analysis of X-ray absorption features in active galactic nuclei (AGN) provides a wealth of information about the physical properties of the matter surrounding supermassive black holes (SMBHs). While standard correlations between the ionisation state, column density, and velocity typically distinguish between disc winds and warm absorbers, some sources exhibit properties that significantly deviate from these trends. We investigate a class of X-ray absorbers, which we define as ultra-thick warm absorbers (UTWAs), identified in a sample of 12 AGN. These absorbers are characterised by exceptionally high column densities and ionisation parameters (($\log (N_{\rm H}/\rm cm^{-2})\gtrsim22.5$ and $0.5 \lesssim \log(\xi/\rm erg~cm~s^{-1})$ $ \lesssim 2.5$)) that lie outside the typical ranges observed in standard warm absorbers. We performed detailed X-ray spectral analyses of both unpublished and archival {\it XMM-Newton}, {\it NuSTAR}, and {\it Swift} datasets to characterise the physical properties of UTWAs in four of these twelve sources. We studied their variability on timescales ranging from days to years and explored their connection with other spectral features. All AGN hosting UTWAs in our sample exhibit extreme soft X-ray variability, in some cases up to an order of magnitude, primarily driven by changes in the absorbing gas. In a subset of these sources (four out of 12), the UTWAs are accompanied by signatures of ultra-fast outflows (UFOs) in the Fe K$\alpha$ energy range. UTWAs represent a rare but crucial phase of AGN feedback. We discuss their physical origin, their potential connection with UFOs, and provide insights into why these high-column density, unusually ionised absorbers appear so rarely in local AGN samples.

The virial coefficient ($f$), which is meant to encapsulate broad-line region (BLR) geometry and kinematics, remains one of the largest sources of systematic uncertainty in black hole mass estimates for Active Galactic Nuclei (AGNs). While the use of a sample average $\langle f \rangle$ enables black hole mass estimates across large samples and cosmological distances, individual AGNs may deviate from this average due to differences in BLR structure and viewing angle. In previous work, we reported marginal evidence for a correlation between $f$ and the shape of the broad H$\beta$ emission line, $\log_{10}(\mathrm{FWHM}/\sigma)$. In this work, we update our sample to include ten new sources with CARAMEL BLR dynamical modeling, increasing both the black hole mass range and statistical power of our analysis. We find marginal evidence for a correlation between $f$ and $\log_{10}(\mathrm{FWHM}/\sigma)$, with a slope and intrinsic scatter consistent with previous results. The confirmation of this trend across a larger sample further supports the idea that line profile shape may reflect BLR properties in a way that directly impacts $f$. If confirmed with future BLR dynamical modeling of sources within a wider range of $\log_{10}(\mathrm{FWHM}/\sigma)$, this relationship could enable empirical estimates of the virial coefficient and improve single-epoch black hole mass estimates across cosmic time.

We present the first uniform gravitational lens modeling analysis of eight doubly imaged quasars from multi-band observations with the Hubble Space Telescope. Previous time-delay cosmography analyses by the TDCOSMO Collaboration have primarily relied on quadruply imaged quasars, while doubly imaged systems, despite being more abundant, remain underutilized due to their fewer geometric constraints. Using an open-source $\texttt{Lenstronomy}$ framework, we reconstruct the lensing systems with a pipeline tailored for doubles. Comparing our results to the literature, the modeled Einstein radii agree at an average of 1.5$\sigma$, which is expected given data and modeling heterogeneity, while modeled image separations differ from Gaia DR2 measurements with an r.m.s of only 3.6 mas. We find a strong correlation between Fermat potential precision and the surface brightness of the spatially extended host arcs, establishing that arc surface brightness is the primary driver of mass model precision in doubly imaged systems. To further quantify the information contributed by the lensed arcs, we performed a conjugate point analysis that uses only the quasar image positions to constrain the lens mass profiles. The resulting posteriors are substantially broader than those from full image modeling, and a strong anti-correlation between mass parameter hypervolume and arc magnitude additionally confirms that arc brightness determines the degree to which the lens mass profile can be constrained in doubles. A hierarchical cosmographic analysis incorporating time-delay measurements and stellar kinematics to infer $\text{H}_0$ will be presented in a subsequent publication. The uniform pipeline and arc surface brightness trends established here will significantly accelerate the construction of time-delay cosmography samples from the large lens populations expected from LSST, Roman, and Euclid.

By using the Doppler images of {\lambda} And, we aim to investigate whether surface temperature information can be reversed to create its activity parameters, by feeding a toy model with solar spectra, based on the surface images. At the same time, we examine whether spot contributions alone are sufficient to explain the observed activity modulation of the RS CVn star {\lambda} And while quantifying the differences with the actual observations of this star that are obtained simultaneously with the Doppler images we use. Due to a lack of publicly available starspot models for its stellar type, we adopt observed solar spectra as the only available approximation of {\lambda} And's spots. These spectra are injected into sequence of full disk temperature map derived from Doppler imaging that represent a full stellar rotation. Using this approach, we show that even with simplified assumptions the spectral behavior of {\lambda} And can be qualitatively reproduced. Toy models such as the one presented in this work procure an additional dimension, providing a relation between the surface structures and chromospheric emissions. It also helps to develop a further understanding for the heating mechanisms of these active giants through comparative techniques, where in this case the spot activity seemingly modulates the chromospheric signal and can explain the bulk of its variations over a rotation.

We present a physics-informed Bayesian neural-network framework to infer neutron-star equations of state from theoretical priors and to propagate the associated uncertainties to stellar observables. Trained on a large and representative ensemble of hadronic EoSs, the model learns $P(\epsilon)$ via stochastic variational inference, incorporating soft constraints at saturation density and from perturbative QCD, together with penalties enforcing monotonicity and causality. The accepted core EoSs are matched to an SLy4 crust and evolved through a unified Tolman-Oppenheimer-Volkoff-plus-tidal solver to generate posterior predictions in the mass-radius ($M$-$R$) and mass-tidal-deformability ($M$-$\Lambda$) planes. The inferred posterior is consistent with NICER radius measurements and the observed $2.0\,M_\odot$ maximum-mass constraint, yielding $R_{1.4}=12.1^{+1.4}_{-0.9}\,\mathrm{km}$, $\Lambda_{1.4}=580^{+520}_{-240}$, and $M_{\mathrm{max}}\simeq 2.11\pm0.05\,M_\odot$ (90\% CI). The resulting canonical tidal deformability can be assessed \emph{a posteriori} against current gravitational-wave constraints. Overall, this framework provides a flexible, non-parametric mapping from microphysical EoS uncertainties to neutron-star observables.

We build a self-consistent model of a warm scattering corona near an accreting black hole in Kerr geometry, in the regime of slow ($\sim 0.01$ Eddington) mass accretion. An iterative Monte Carlo procedure is developed that incorporates self-consistently the effects of Compton scattering and electron-positron pair creation, as well as general relativistic lensing and frame dragging effects. Soft thermal photons are seeded in the inner disk and the velocity dispersion of the electrons and positrons adjusted to yield a fixed seed luminosity amplification through Compton scattering. A simple kinematic prescription is also added for bulk outflow. Pair creation by photon collisions raises significantly the density of scattering charges in and around the innermost ion disk, which is assumed to be geometrically thick and rarefied compared with the disk outside 10 gravitational radii. The self-consistent pair cloud is concentrated closer to the BH. The spectrum and polarization of the escaping X-rays are recorded as a function of the observer's orientation. The temperature and Compton parameter measured from the output spectra using the compPS package are consistent with fits to binary BH data in the hardest spectral state; the polarization degree rises to $4-10\%$ through the 2-8 keV band with allowance for $e^\pm$ upflow from the BH equator.

Although well studied, our understanding of the mass ejection mechanisms of cataclysmic variables remains incomplete. Recent work suggests that binary interaction plays an important role in driving and shaping this mass ejection and may affect the long-term evolution of the system. In this paper, we perform a three-dimensional moving-mesh hydrodynamic simulation of a cataclysmic variable system to study the effect of binary interaction on mass ejection. We find that once the flow crosses the ${\rm L}_1$ Lagrange point, the material is ejected roughly isotropically. This can be seen in a roughly spherical distribution of the ejecta at large radii. We also show that the ${\rm L}_2$ Lagrange point is not important in the ejection of mass, contrary to the assumption in some previous work in this area. Finally, we find that the specific angular momentum of the ejected material is larger than its initial specific angular momentum. This enhanced angular momentum ejection likely affects the long-term evolution of the binary system.

We investigate the role of hierarchical assembly in the angular momentum (AM) evolution of galaxies using a sample of 471 Milky Way-mass galaxies from the TNG-50 simulation. While galaxy orientation is often attributed to tidal torques and the cooling of gas within halos, we demonstrate that galaxy reorientation (tilting) is a common consequence of satellite accretion. Specifically, 80+/-2% of galaxies show alignment between their present-day AM and the orbital AM of their most massive (dominant) merger progenitor. This reorientation typically results in changes of around 50% in the galaxies' specific AM, with the most significant shifts occurring in galaxies that were initially highly misaligned. We find only a weak influence from the second most massive merger, and negligible impacts from surviving satellites. We show that accreted stellar halos encode the history of this reorientation. Driven by the same accretion event, the main bodies of galaxies and their stellar halos tend to co-align, with 81+/-2% of TNG-50 stellar halos showing prograde rotation relative to the galaxy. This signature will be detectable through major-axis kinematics with 30-meter class telescopes for Milky Way mass galaxies, offering a valuable observational test of this picture. While halo rotation directly constrains the specific AM of mergers within the last ~7 Gyr, this kinematic `memory' is largely erased for older and more radial events. Consequently, the Milky Way itself appears to be a notable exception to the general merger-driven trend: TNG-50 analogs with early, radial, and low angular momentum dominant mergers affect present-day disk orientation minimally. The current MW disk orientation may instead reflect the accumulated influences of gas accretion or dark matter torques.

Core collapse supernova modeling has advanced considerably since the first numerical simulations were performed sixty years ago. In particular, the last decade has brought us sophisticated three-dimensional models with significant predictive capabilities -- e.g., for core collapse supernova gravitational wave emission. The six decades of modeling have shown us the importance of individual components of these general relativistic neutrino radiation magnetohydrodynamics events -- specifically, the importance of neutrino kinetics, fluid instabilities, magnetic fields, strong gravity, and the nuclear equation of state and neutrino--matter interactions calculated in a manner consistent with the equation of state. They have also shown us that simulation outcomes are sensitive to variations in the treatment of these ingredients, demanding a level of rigor that has not yet been consistently met by modelers. The efficacy of the neutrino shock reheating mechanism for core collapse supernovae has been demonstrated. The models now require an improved quantitative predictive capability, which will be achieved through increased sophistication in the treatment of model components, both macroscopic (e.g., strong-field gravity) and microscopic (e.g., neutrino--matter interactions). Advancement of core collapse supernova theory will also require the cooperation of modelers in other fields, especially stellar evolution and nuclear theory, to meet the level of rigor required to make the most of the eventuality of a Galactic core collapse supernova and its multimessenger emissions.

The sky-averaged redshifted 21 cm signal from Cosmic Dawn is a uniquely sensitive tracer of early heating and ionisation, but it remains challenging to measure directly. The Sunyaev-Zel'dovich effect of the 21 cm background (SZE-21cm) provides a complementary route: Comptonisation of the incident low-frequency background by hot electrons in galaxy clusters produces a spectral distortion that can be recovered as a difference between the line of sight through a galaxy cluster and a nearby blank-sky reference, and is therefore naturally compatible with interferometric observations. We use semi-numerical simulations of the global 21 cm background, together with a relativistic scattering kernel built from the Maxwell-Juttner electron distribution, to assess how well the SZE-21cm separates physically distinct Cosmic Dawn scenarios. The model suite varies star-formation efficiency, X-ray spectral hardness, heating timing, and the suppression of low-mass sources; SZE-21cm spectra are computed over 45-200 MHz. Separability is quantified through feature-based summaries, standardised residual spectra, and a band-integrated pairwise separability index that combines seed-to-seed scatter with an astrophysical variance layer derived from coeval ON-aperture / OFF-annulus statistics. The resulting indices are intrinsic and instrument-free, and therefore upper bounds on what a real experiment with finite thermal noise can achieve. Heating-timing variations produce the strongest separations, while the X-ray hardness variations explored here are nearly degenerate with the fiducial case once the ON-OFF variance is included. We also propagate an EDGES-like benchmark curve as a morphological stress test of the framework, not as a physically validated model, illustrating how anomalous global-signal morphologies would map into the SZE-21cm.

Electromagnetic signals propagating across interstellar distances are subject to simultaneous distortion by seven distinct physical mechanisms: relativistic Doppler shift, stellar aberration, interstellar medium dispersion, special relativistic time dilation, general relativistic gravitational time dilation, cosmological redshift, and atmospheric transmission losses. Each effect is individually well established, yet to our knowledge no existing public browser-based framework applies all seven effects simultaneously to a catalog of confirmed exoplanets using real measured stellar and planetary parameters. This paper presents the RSCL Earth Lookback Simulator, an open-source browser-based framework that addresses this gap. Seven physics engines operate in parallel on a curated catalog of 62 confirmed Milky Way exoplanets, drawing all physical parameters from the NASA Exoplanet Archive and the NE2001 galactic electron density model. Computed quantities are checked for consistency against published reference values. The framework is deployed as a public open-source application and is designed to serve researchers in SETI, exoplanet science, astrobiology, and space mission planning.

The radio emission mechanisms from accreting protoplanets, and their variability, link observations and physical properties. We revisit the variability of the ~343GHz (ALMA Band7) flux density from PDS70c (F_B7). The subtraction of the extended time-averaged signal may enable the measurement of the flux density from variable and embedded point sources. Visibility alignment and self-calibration yields close to thermal residuals in each execution block (EB) of ALMA observations, allowing the time-differential photometry of point-source in the visibility domain. The variability of PDS70c is checked against synthetic control point sources. In images of the 2017 ALMA dataset, with three ~1h EBs, PDS70c was detected only on 6 Dec. 2017, where F_B7 rose by 228%+-69% (3.3sigma). Time-differential photometry confirms a rise by 170%+-46% (3.7sigma). An application to ~2h EBs from the 2023 dataset resulted in constant flux densities, within a scatter of ~15%. However, F_B7(t) shows some scatter when splitting the deep 2023 EBs in 20min intervals, with a chi2 test significant at 2.6sigma, and an intrinsic dispersion of 49%21%. The radio variability of PDS70c, observed over hours but averaged out on longer timescales, is indeed expected if the signal is due to HI free-free from an accretion shock on a circum-planetary disk surface. A planet-to-environment mass ratio <1E-4 is required to avoid smoothing by radiative diffusion if the signal is due to thermal emission from the environment.

Aims. We seek to (a) study 1D Cartesian ambipolar diffusion near null points; (b) characterise the nonlinear eigenmodes for ambipolar diffusion; (c) propose tests for ambipolar diffusion solvers in MHD codes. Methods. (a) Direct analysis is used to find analytical solutions for ambipolar diffusion. (b) To study the eigenmodes, we solve the ODE for self-similar solutions of the 1D ambipolar diffusion equation using phase-plane techniques. We also solve the general time-dependent 1D problem for initial conditions of interest. (c) We test the Bifrost code by trying to reproduce the behaviour of the eigenmodes. Results. (a) A stagnation-point flow solution was found with a uniform flux transfer rate across three regions: an external advection region; an internal ambipolar diffusion region with magnetic profile B propto x**(1/3); and an innermost Ohmic region with B propto x; in the latter, flux annihilation occurs at a rate imposed by the advection. (b) Both symmetric and antisymmetric eigenmode solutions to the ambipolar diffusion problem are found with sharp current sheets at the internal nulls. The time evolution of the eigenmodes (pure or perturbed) is probed, showing how higher-order eigenmodes, or perturbed ones, evolve in time towards the lowest-order allowable eigenmodes. (c) The Bifrost code reproduces the behaviour of the eigenmodes with excellent accuracy. Conclusions. Stagnation-point configurations exist with ambipolar diffusion carrying magnetic flux in an inner layer and serving as an intermediary between the external advection and an Ohmic-diffusion core around the null. Our tests are compatible with the hypothesis that zero-flux higher harmonics of the self-similar equation evolve toward either the first symmetric or antisymmetric harmonic. The self-similar solutions can serve as strong tests for ambipolar diffusion solvers in general MHD codes.

In the coldest regions of the solar atmosphere, lingering discrepancies between models and observations may be caused by the Thermal Farley-Buneman Instability (TFBI). This meter-scale, electrostatic, collisional, multifluid plasma instability converts energy from neutral flows into turbulent motions and heating. In the neutral frame of reference, these neutral flows manifest as an electric field which can drive the TFBI. In this work, we simulate the TFBI across a broad range of solar chromospheric conditions. We find clear proportionality between between TFBI-driven relative temperature increases of charged species ($\Delta T_{s}^{\text{(turb)}} / T_{s}^{(0)}$) and driving electric field strength relative to the theoretical threshold field required for TFBI growth. We also discover a correlation between relative driving field strength and turbulent motions. Additionally, the TFBI consistently causes average current density to rotate towards the driving field, with Pederson/ambipolar component ($\vec{J} \cdot \hat{E}^{(0)}$) increasing by up to roughly 60% while the Hall component ($\vec{J} \cdot \hat{E}^{(0)} \times \hat{B}$) decreases in magnitude by up to roughly 80%. Meanwhile, we find TFBI-driven turbulence increases neutral heating rates by $(43\pm7)\%$ on average, with 85% (28/33) of simulations having mean increase more than 29%, and a flat line of best fit suggesting zero correlation with driving field.

The atmospheres of hot Jupiters lie in a dynamical regime without a solar system analogue. The strongly irradiated daysides reach temperatures sufficiently hot for substantial thermal ionization of atmospheric species, resulting in flows that can interact with the planetary magnetic field. These magnetic effects can significantly impact wind speeds, atmospheric temperatures, and large-scale circulation patterns. Previous work combining 3D atmospheric models and magnetic prescriptions has shown the impact of magnetic effects on temperature and velocity profiles are dependent on local atmospheric properties as well as the set of assumptions employed by the magnetic prescription. In this work, we examine a commonly employed magnetic model--a perfectly aligned dipole--in 3D General Circulation Models (GCMs) and extend this framework to allow for tilting of the deep-seated internal magnetic dipole field relative to the axis of rotation. We find that the inclusion of a tilted dipole introduces pronounced north-south asymmetries into the temperature profile leading to latitudinally shifted hotpots and deflection of winds that would otherwise be axially symmetric. We additionally simulate JWST/NIRSpec phase curves. We find that the strength of the magnetic field has the most significant effect on the simulated phase curves, with stronger magnetic fields increasing the amplitude of the phase curve and reducing the hot spot offset. Our model can provide qualitative insight into how the magnetic dipole strength or orientation may influence the large scale atmospheric dynamics and represents one of the most sophisticated incorporations of magnetic effects in GCMs for hot Jupiter atmospheres to date.

Low-luminosity active galactic nuclei (LLAGN) often host weak radio jets whose propagation is shaped by the surrounding interstellar medium. We investigate the nearby LLAGN NGC7213 to assess its ability to launch collimated outflows beyond the nucleus and to characterise the origin and variability of newly identified radio components from parsec to kiloparsec scales. We present new MeerKAT, uGMRT, ATCA, and Australian Long Baseline Array (LBA) observations from 300 MHz to 9 GHz. We analyse the morphology and spectra of the kiloparsec-scale emission and use LBA monitoring to probe the parsec-scale core. We discover a pair of compact radio knots located symmetrically at a projected distance of ~5 kpc north and south of the nucleus. The knots have nearly identical flux densities and flat radio spectra from 300 MHz to at least 5.5 GHz, with no significant spectral or geometric asymmetry. The LBA monitoring shows that the nuclear source remains unresolved at all epochs, constraining the 8 GHz emission to sub-parsec scales, and reveals significant variability on decade-long and month-long timescales, including a flux-density increase of ~40 mJy over six months. The symmetry, spectra, and physical properties of the kiloparsec-scale knots support their interpretation as compact termination shocks of a weak or intermittent jet launched by NGC7213 and confined by the dense, disturbed interstellar medium. The unresolved, variable parsec-scale core indicates that the high-frequency radio variability originates in the innermost jet region, likely linked to a recent increase in nuclear activity. NGC7213 is therefore a nearby example of how weak jets in low-accretion AGN can produce both compact nuclear variability and symmetric kiloparsec-scale structures in complex environments.

$\beta$ Cep stars in eclipsing binary (EB) systems give us an opportunity to put observational constraints on their structure and stellar parameters. We present a comprehensive analysis of the $\beta$ Cep star in the EB V446 Cep, using \textit{TESS} photometry and HERMES spectra. We calculate the stellar and orbital parameters using light curve modelling and spectral disentangling. The EB has an orbital period of $3.808567 \pm 0.000012$ d and a mass ratio of $0.1550 \pm 0.0012$. We find the $\beta$ Cep star to have a mass of $10.68 \pm 0.06$ $\mathrm{M_{\odot}}$, a radius of $5.864 \pm 0.033$ $\mathrm{R}_{\odot}$, and a $T_{\rm eff}$ of $24220 \pm 180$ K. The secondary has a mass of $1.657 \pm 0.017$ $\mathrm{M_{\odot}}$, a radius of $1.530 \pm 0.014$ $\mathrm{R}_{\odot}$, and a $T_{\rm eff}$ of $9080 \pm 390$ K. We also extract the abundances of C, N, O, Mg, and Si for the $\beta$ Cep star, which are found to be consistent with galactic OB binaries. We identified 21 distinct pulsation frequencies, with the dominant mode at 10.24324 d$^{-1}$, which corresponds to a near-harmonic of the system's orbital frequency. The two stars in the EB have asynchronous rotation, with both stars rotating faster than the orbital frequency. We detect a companion to the EB using eclipse timing variations and period changes of the dominant pulsation frequency. We calculate the minimum mass of this tertiary companion to be $4.11 \pm 0.32$ $\mathrm{M_{\odot}}$ which is on an orbit of 2303$\pm$69 d around the EB. Using spectral energy distributions and MIST isochrones, we conclude that V446 Cep is either a co-evolving hierarchical 2+2 quadruple or a triple system where the third body is a compact object.

We study the early post-bounce neutrino signal of the published Garching $15\,M_\odot$ rotating core-collapse supernova (CCSN) sequence consisting of non-rotating (NR), slowly rotating (SR, $\Omega_0=0.5$ rad\,s$^{-1}$), and fast-rotating (FR, $\Omega_0=150$ rad\,s$^{-1}$, artificially boosted ${\sim}300{\times}$) three-dimensional models. We present a new analysis of these publicly available simulation data; no new simulations were performed. Our central result, for this specific model sequence, is that SR and FR shift the integrated spectral moments in \emph{opposite directions} relative to NR: FR drives the spectra toward softer, more-pinched states, while SR moves them weakly toward harder, less-pinched states. Placed in a spectral-shift plane $(\Delta\langle E\rangle_L,\,\Delta\alpha_L)$, NR sits at the origin, and SR and FR occupy \emph{diagonally opposite quadrants}, making the non-monotonic response immediately visible as an anti-correlation in two spectral dimensions simultaneously. The focus is the accretion interval $t_{\rm pb}=0.05$--$0.30$\,s, where the rotation imprint is strongest. Quantitatively, fast rotation produces $\Delta\langle E_{\nu_e}\rangle_L=-0.513$\,MeV and $\Delta\alpha_{\nu_e}=+0.161$, with corresponding shifts $\Delta\langle E_{\bar\nu_e}\rangle_L=-0.440$\,MeV and $\Delta\alpha_{\bar\nu_e}=+0.173$; the SR shifts are an order of magnitude smaller and in the opposite sense. The fast-rotation signature is coherent across all $15\,488$ lines of sight and is established during early accretion. With only three models from a single progenitor family, this result is a phenomenological characterization of one published sequence and a suggestive indication of a non-monotonic, possibly strongly nonlinear, rotational response within this sequence; the functional form and generality of the dependence on $\Omega_0$ remain unconstrained.

We present a comprehensive analysis of circumgalactic Lya nebulae around 59 unobscured and 26 obscured quasars at z=2-3, observed with the Keck Cosmic Web Imager (KCWI), to constrain the nature of active galactic nuclei (AGN) at cosmic noon. We find that Lya nebulae around unobscured quasars are significantly less symmetric having a symmetry parameter of a_w=0.2-0.6 and more spatially extended having a scale length of r_h=10.7+/-0.5 kpc than those around obscured quasars (a_w=0.6-0.8; r_h=6.6-7.7 kpc).Unobscured quasars also exhibit steeply declining velocity dispersion profiles with the slope of -4.3+/-0.4 km s^-1 kpc^-1, indicative of large-scale outflows, whereas obscured quasars display flat profiles (-0.2+/-0.7 and -0.6+/-0.4 km s^-1 kpc^-1). The degree of quasar obscuration appears to be intrinsically linked to nebular asymmetry and extent, a relationship that could be in tension with the standard orientation-based AGN unified model, as it expects unobscured-quasar nebulae to be more symmetric and compact. These results naturally fit the evolutionary scenario, where AGN feedback drives a transition from an obscured to an unobscured phase-progressively redistributing gas to larger radii, introducing anisotropy, and driving turbulence. Taken together, our findings favor the evolutionary scenario over the purely orientation-based unified model for quasars at cosmic noon.

The virial factor $f$ is critical for accurate supermassive black hole (SMBH) mass measurements using reverberation mapping (RM) and the radius--luminosity ($R$--$L$) relation, yet its value remains highly uncertain. While traditional models assume axisymmetric broad-line region (BLR) geometries, growing evidence suggests that BLRs may possess more complex, asymmetric structures. We systematically investigate the impact of elliptical-disk BLR geometries on SMBH mass determinations through comprehensive numerical simulations. By computing emission-line profiles, emissivity-weighted time lags, and the corresponding virial factor $f$ over a wide range of eccentricities, orientations, and inclinations, we find that even in purely virialized systems, geometric effects alone can cause $f$ to vary by more than an order of magnitude and can mimic observational signatures typically attributed to radiation pressure. Additionally, local broadening introduces further systematic uncertainties in velocity width measurements, biasing $f$ by up to a factor of $\sim$3. Asymmetric BLR configurations also induce a scatter of $\sim$0.18 dex in the $R$--$L$ relation due to projection effects, comparable to the intrinsic scatter observed in RM studies. These results challenge the conventional attribution of RM uncertainties to non-virial motions or radiation pressure, and instead highlight the fundamental role of BLR geometry in SMBH mass measurements.

Marginalizing over roughly 12 effective-field-theory (EFT) nuisance parameters per tracer per redshift bin is the dominant systematic cost in full-shape galaxy power spectrum analyses. Simulation-based priors (SBP) can tighten these parameters but rely on N-body simulations and halo-occupation-distribution (HOD) models. We propose multi-survey priors: a data-driven alternative that calibrates EFT parameters from the multi-tracer analysis of overlapping spectroscopic surveys. In the $\sim\!1{,}200\;\text{deg}^2$ Prime Focus Spectrograph (PFS)--Dark Energy Spectroscopic Instrument (DESI) overlap at $0.6<z<1.6$, up to 4 tracers (PFS-ELG, DESI-ELG, DESI-LRG, DESI-QSO) and 10 cross-spectra per redshift bin provide model-independent constraints on the DESI nuisance parameters. Cross-spectra between different galaxy populations carry zero stochastic contribution, cleanly separating shot noise from signal. Exporting the calibrated priors to the full $14{,}000\;\text{deg}^2$ DESI footprint of the DESI LRG1--3, ELG1--2 and QSO samples improves $\sigma(f\sigma_8)$ by 8\% (7--25\% per sample) and $\sigma(M_\nu)$ by 54\% (46--71\% per sample) at $k_{\rm max}=0.20\,h\,\mathrm{Mpc}^{-1}$. A parameter importance decomposition reveals that the dominant driver is the calibration of the $b_1\sigma_8$ prior -- constrained from a flat prior to $\sigma\approx 0.17$ by the multi-tracer Fisher -- which accounts for $\sim\!70\%$ of the $f\sigma_8$ gain and $\sim\!97\%$ of the $M_\nu$ gain by breaking the $b_1\sigma_8$--$f\sigma_8$ degeneracy intrinsic to single-tracer analyses. Multi-survey prior calibration parallels the SBP approach, which tightens $b_1$ through HOD model assumptions; multi-survey priors provide a model-independent consistency check on these assumptions and generalize to arbitrary combinations of overlapping spectroscopic surveys.

We present multi-epoch optical spectroscopy of the isolated elliptical galaxy UNAM-KIAS 613, hosting a low-luminosity Type 1 AGN. Analysis of archival Sloan Digital Sky Survey (SDSS) data from 2006 reveals a distinctive double-peaked broad H$\alpha$ profile, tentatively modeled by a relativistic accretion disk. Follow-up observations in 2018 and 2023 show the disappearance of the red and blue wings, leaving only a single-peaked, central broad component. No significant continuum variability is detected in ASAS-SN and Catalina light curves over 2012-2025, and multi-wavelength data (radio, mid-IR, X-ray) confirm a sub-Eddington, radio-quiet AGN (Eddington ratio $\approx$0.03-0.04, black hole mass $\approx$10$^{7.2}$ M$\odot$). We propose that the double-peak structure is in reality transient, and arose from a one-time bipolar outflow event rather than a stable disk or from a Tidal Disruption Event. The mid-IR SED and radio luminosity place UK 613 on the boundary between AGN and star formation dominance, suggesting residual star formation, while we have found that the isolated environment seems to be prone to the rejuvenation of ellipticals by recent ($\lesssim$ 1 Gyr) cold gas. We also examined its location within the cosmic web with the aim of identifying possible distinctive effects imprinted on its spectroscopic properties. Ultimately, our results are consistent that UNAM-KIAS 613 might have under gone a ''turn-off'' of the accretion disk emitting region or a transition between a radiatively-inefficient and radiatively-efficient accretion mode, and highlight the complex interplay of disk, outflow, host processes and environment in low-accretion, low-black hole mass AGNs, an AGN population still largely unexplored to-date.

Based on models derived from Earth's magnetotail, other planets with dipole magnetic fields, including Mercury, Jupiter, and Saturn, were expected to possess similar magnetotail configurations. In this traditional picture, the majority of plasma is confined near the magnetic equator within a plasma sheet (or plasma disc), whereas higher-latitude regions feature strong magnetic fields that are open to the solar wind, forming magnetospheric lobes. However, auroral observations and recent simulations have shown that Jupiter's magnetic topology differs markedly from this picture, particularly in its high-latitude regions where magnetic field lines are predominantly closed. This discrepancy calls for a re-examination of high-latitude magnetospheric structure at Jupiter. Here, using Juno measurements acquired between 2016 and 2022, we show that Jupiter's nightside high latitudes host a persistent current-sheet-like structure above about 40 degrees magnetic latitude near midnight. This structure contains internally sourced oxygen and sulfur ions and exhibits azimuthal magnetic signatures opposite to the bend-back of the equatorial current sheet. These findings indicate that the canonical picture of planetary magnetotail architecture requires revision. Our results provide new insight into the architecture of rapidly rotating magnetospheres and offer a framework for interpreting magnetospheric structures at exoplanets.

Chondrules are thought to have formed during transient flash-heating events in dust-enriched regions of the solar protoplanetary disk. Although laboratory studies have characterized the oxygen isotopic compositions of chondritic materials, quantitative interpretations based on simulations of disk formation and evolution remain limited. Here, we perform one-dimensional simulations of disk formation and evolution by solving a diffusion--advection equation with mass infall from the parental cloud core. We compute the temporal evolution of oxygen isotopic compositions using an experimentally derived isotope-exchange model. We examine how the oxygen isotopic signatures of the disk depend on the radial distribution of infalling material and the composition of the parental cloud core. We find that the oxygen isotopic compositions of carbonaceous-chondrite chondrules can be reproduced if either (i) the radial extent of mass infall onto the disk is moderate ($\sim 10~{\rm au}$), or (ii) it is large ($> 10~{\rm au}$) and the parental cloud core was ice-depleted and/or experienced weaker CO self-shielding than is commonly assumed. We further suggest the scenario that the observed bimodal trends in oxygen isotopic composition and redox state reflect the partial escape of H$_{2}$O vapor from chondrule-forming regions during heating. In contrast, if ordinary-chondrite chondrules formed inside the snow line under background temperatures of $\lesssim 500~{\rm K}$, their oxygen isotopic compositions may be difficult to explain within the present disk-evolution model, because oxygen isotopic exchange between silicates and vapor species proceeds efficiently only in the inner disk at $T \gtrsim 500$--$600~{\rm K}$.

The lifetime of protoplanetary discs is a critical factor for planet formation. Although the mean disc lifetime provides an estimate of the typical period available for planet formation, it does not capture the substantial variability in individual disc lifetimes or their dependence on host star mass. This study addresses these limitations by deriving the disc lifetime distribution as a function of stellar mass. Our results reveal a pronounced mass-dependence. Performing a phenomenological fit using a Weibull distribution, we find the maxima of the distributions at $t_{max}^H =$3.72 Myr for high-mass stars ($\approx$ 1.00--3.00 $M_{\odot}$) and $t_{max}^L =$ 7.20 Myr for low-mass stars ($\approx$ 0.01--0.20 $M_{\odot}$) assuming an initial disc fraction of $f_{init} = 0.8$. All distributions are broad (typically 3.2 Myr $< \sigma <$ 4.7 Myr), with the distribution for low-mass stars being somewhat broader. Our analysis indicates that not all stars are initially surrounded by a disc (60% $< f_{init} <$ 90% at cluster zero age), and that the initial disc fraction is even lower ($f_{init} \approx$ 40%) for higher-mass stars. The potential mechanisms responsible for the observed spread and mass-dependence of disc lifetime distributions and initial disc fractions are discussed. Our primary aim is to demonstrate the methodology; more robust constraints will require improved data on mass-dependent disc fractions. Nevertheless, the derived mass-dependent disc lifetime distributions can already serve as a valuable input or a benchmark for planet-formation synthesis models.

We present timing and orbital phase-resolved polarimetry of the millisecond pulsar (MSP) J2101$-$4802, having a spin period of 9.48~ms and dispersion measure (DM) $25.05\ \mathrm{pc\ cm^{-3}}$ discovered with the Giant Meter Radio Telescope (GMRT). From the phase-connected timing of this MSP spanning 3.7 years, we identify that PSR J2101-4802 is in a $\sim$1-day binary orbit with a likely helium-white-dwarf (He-WD) companion having a median companion mass of $\simeq0.15\, M_\odot$, consistent with canonical recycling in the Galactic field. The timing solution further reveals an unusually large orbital period derivative, $\dot{P}_b$ ($\sim10^{-11}\,{\rm s\,s}^{-1}$), compared to typical Galactic-field MSP--HeWD binaries, which cannot be explained by the contributions from kinematic effects (Shklovskii and Galactic acceleration) or general-relativistic damping. Using wideband, full-Stokes observations, we also trace the linear and circular polarization variation across the orbital phase and fit a rotating-vector model (RVM) to its position-angle swing across the pulse phase, yielding constraints on the emission geometry (magnetic inclination and impact angle) of this system. The combination of a $\sim$1-day orbit, $\sim0.15\,M_\odot$ companion, modest spin-down power, unusually large $\dot{P}_b$, and phase-locked magnetized intrabinary plasma signatures suggests that PSR~J2101$-$4802 represents a transitional system linking redback-like spiders to detached He--WD MSP binaries.

Sodium (Na) is a moderately volatile element in the lunar exosphere, released from the surface through thermal and non-thermal processes. We present a combined analysis of Chandrayaan-2 CLASS surface Na abundance, LADEE-UVS exospheric measurements, and DIVINER surface temperature data to investigate the coupling between surface and exospheric Na. Surface Na exhibits a pronounced diurnal modulation, with depletion during lunar daytime and enhancement at dawn and dusk, consistent with thermal desorption from weakly bound multilayer reservoirs (>1 ML). Exospheric Na shows longitudinal enhancements above low-albedo mare regions, whereas CLASS-derived surface abundances reveal no significant compositional differences between mare and highland terrains. The observed exospheric structure correlates strongly with surface temperature and albedo, implicating temperature-dependent thermal desorption as the dominant release mechanism at low altitudes. These findings indicate that the spatial variability of Na release efficiency, rather than surface Na abundance, primarily governs the distribution of lunar exospheric sodium. This study places a new observational evidence on sodium retention on the lunar surface and release mechanisms and demonstrates the dominant influence of surface thermo-physics in controlling the near-surface lunar sodium exosphere.

Einstein Telescope (ET) is a third-generation gravitational wave (GW) detector with tenfold better sensitivity compared to the advanced LIGO detectors. It will be capable of observing copious stellar mass binary black hole mergers upto a redshift of 10 which will make it especially useful for cosmography. We generate a mock gravitational wave event catalog for the Einstein Telescope and show the recoverability of either the Hubble constant ($H_0$) or the matter density parameter ($\Omega_{\rm m}$). We present a simple, effective and fast technique for inferring $H_0$ (or $\Omega_{\rm m}$) using the intrinsic chirp mass spectrum of black hole binaries, and investigate the efficacy of the method assuming the standard model of cosmology. If only $H_0$ has to be constrained, we find that at least one year of ET's observation will be required to achieve 1% uncertainty. With the same amount of observation, $\Omega_{\rm m}$ can be constrained to within 4\% uncertainty. With ET operating as a standalone instrument, we show that the GW spectral sirens detected by it can constrain the Hubble constant.

LAMOST J052016.79+345651.7 was identified as an EW-type eclipsing binary by Chen et al. when studying the periodic variable stars based on the ZTF telescope. An orbital period of 0.3507818 days has been reported. Using the ZTF g, r, i band light curves, we reproduced the orbital period and obtained a phase folded diagram. The multi-band apparent magnitudes from Pan-STARRS, 2MASS, and WISE, the color indices, and the infrared excess in the WISE w4 band all indicate that LAMOST J0520 contains cold circumstellar material. All 19 LRS from LAMOST exhibit prominent Halpha emission lines, along with clear N II and S II emission lines, indicating that LAMOST J0520 contains optically thin, warm ionized gas with extremely low electron density. From the 19 spectra, an effective temperature of 6200 \pm 400 K can be obtained. Therefore, the emission lines likely originate from shock-driven outflows and mass ejection, while the infrared excess likely comes from dust formed as the outflows cool. We performed light curve fitting and evolutionary simulation study on LAMOST J0520 using PHOEBE and MESA, respectively. The phase shift of the fitted model can be uniquely determined, but the inclination and the fillout_{factor} are degenerate. Considering the angular momentum loss process, the evolutionary simulation from detached binaries to contact binaries can reflect the main evolutionary process of LAMOST J0520. When the orbital period of the evolutionary model is 0.351 days, the other parameters are generally consistent with the observed characteristics of LAMOST J0520. Considering mass loss, LAMOST J052016.79+345651.7 will evolve into a blue straggler star in the future. Future LAMOST medium resolution time-domain spectra of LAMOST J0520 may offer an opportunity to reveal more detailed physical processes.

We investigate a hierarchy of interacting dark energy (IDE) models featuring a non-gravitational coupling between dark matter and dark energy. Specifically, we examine scenarios where the background interaction kernel, $Q = 3H(\delta + \eta a)\rho_\mathrm{de}$, allows for both constant and dynamical coupling parameters. Adopting the CPL parametrization for the dark energy equation of state, $w_\mathrm{de} = w_0 + w_a(1-a)$, we derive closed analytical expressions for the energy densities of dark matter and dark energy. Afterwards, we obtain observational constraints using joint combinations of DESI DR2 baryon acoustic oscillations, Pantheon$+$ Type Ia supernovae, and Planck$+$ACT compressed cosmic microwave background likelihoods. For constant coupling models, we find parametric deviations from $\Lambda$ ranging from $2.7\sigma$ to $2.9\sigma$; however, for interactions with dynamical couplings, these significances are reduced to $1.3\sigma$--$1.5\sigma$. Ultimately, our Bayesian model comparison reveals that no investigated IDE scenario is statistically preferred over the concordance $\Lambda$CDM model. These results highlight the necessity of reporting Bayesian evidence alongside conventional frequentist maximum-likelihood analyses to ensure robust cosmological claims concerning dark energy evolution and interaction.

We develop a field-level posterior for cosmological data by marginalizing over initial conditions and noise in a general forward model. While our focus is on large-scale structure data, the results generalize to any weakly non-Gaussian observable. Moreover, the construction is non-perturbative with respect to the forward model and applies equally well to perturbative calculations, simulation-based predictions, and more general effective descriptions. Expanding the FLP around its Gaussian limit, we derive a general expression for the Fisher matrix and reorganize the field-level information into contributions associated with the connected correlators of the evolved field. This makes explicit which terms are captured by likelihood analyses based on the power spectrum, the bispectrum, or finite sets of summary statistics, and which are lost under compression. We recover the standard Gaussian-covariance result for the power spectrum, show that the Gaussian bispectrum likelihood reproduces the corresponding field-level contribution, and show how cross-covariances among summaries progressively reconstruct more of the full field-level information. As an application to the BAO scale, we show how the field contains all the information required for its optimal reconstruction in the presence of noise, and identify the contributions in the FLP needed to attain this limit. We also show that the reconstruction of the initial field arises naturally as a byproduct of our approach, yielding the optimal estimate of the initial conditions given the data and the noise. Our results provide a unified framework to compare field-level and correlator-based inference, to quantify the information loss induced by compression, and to explore the role of stochasticity.

When studying massive stars and their life cycles, rotation plays a key role. Hence, understanding the rotation of these stars is crucial when determining their properties, or for constraining evolutionary models. We examine the reliability of the standard methods to derive projected rotation speeds vsini from photospheric spectra of hot, massive stars in the presence of large turbulent velocities. We include rotation in the spectral synthesis of O-stars by means of three-dimensional model atmospheres showing significant photospheric turbulent velocities. We then use these as mock-observations to back-test the Fourier Transform and goodness-of-fit methods commonly used for empirical determination of vsini when the turbulent velocity field is not known. When the expected vsini>v_mac, with v_mac the macroturbulent velocity, FT vsini determinations (most of the time) give reasonable results. However, if vsini < v_mac the method is no longer reliable. Results from the GOF method show that if one parameter is not significantly larger than the other, empirical best-fit values may be located in a large region of the vsini-v_mac parameter space, independent of the true values. The degenerate region follows well the empirical formula found by Howarth et al. (2007), sqrt(v_mac^2/2+vsini^2/4). In other words, only this sum can be constrained by GOF observational analysis. Our analysis shows clearly that, generally, only the sum sqrt(v_mac^2/2+vsini^2/4) can be constrained through the standard spectroscopic methods used to infer these parameters individually. Only in the case where one of the two clearly dominates, can good constraints on the dominating parameter be derived. This demonstrates that previously found empirical correlations between vsini and v_mac as well as derived statistical distributions of observed rotation rates for O-star populations will need to be re-analysed and interpreted.

Gravitational microlensing constraints on non-standard compact objects are conventionally derived assuming lenses trace the dark matter halo with velocities following a Maxwell-Boltzmann distribution. However, a variety of theoretical scenarios predict populations of compact objects whose velocities deviate dramatically from those of virialized halo dark matter -- ultrarelativistic primordial black holes from cosmic string collapse, mirror neutron stars, gravitationally kicked black hole merger remnants, dark matter nuggets, free floaters ejected from gravitationally bound systems, disk-formed compact objects, and so on. For a given Einstein crossing time, the speed-mass degeneracy inherent in it means that fast (slow) lenses produce events at larger (smaller) masses than spanned by standard windows, opening qualitatively new regions of parameter space. After deriving model-independent upper limits on the microlensing event rate, we obtain mass-dependent constraints on the density of lens populations with speeds spanning $10^{-4}c-10^{-1}c$ from surveys of M31 by Subaru-HSC and the LMC by OGLE with different observing cadences. We do this for two benchmark velocity distributions -- Maxwell-Boltzmann and Dirac delta -- and two spatial distributions -- uniform and NFW, and exclude lens densities and masses that differ from dark matter constraints by orders of magnitude. We examine the effect of the transverse motion of the source and observer relative to the lensing tube, which becomes significant for our slow lenses. We also show that, unlike in dark matter searches, for our fast lenses an increase in the cadence of observations would probe smaller masses without suppression of event rates from the finite source and wave optics effects.

The rotation measure (RM) and dispersion measure (DM) of fast radio bursts (FRBs) serve as critical probes of the magneto-ionic environments along the line of sight. The significant temporal evolution of RM observed in some repeating FRBs is generally attributed to the local environment of the source, since the intergalactic medium is not expected to vary on such short timescales. Recent observations of repeating FRB 20201124A and FRB 20220529 exhibit complex RM phenomenology, including large-amplitude global fluctuations and short-term substructures. Here, we attribute these short-term RM variations to the ponderomotive force exerted by inertial \alfven~waves (IAWs). We propose that IAWs, generated via magnetic reconnection or turbulent cascades in a low-$\beta$ plasma, induce nonlinear density perturbations in the source environment. We demonstrate that the resulting plasma density redistribution can produce RM suppression consistent with observed substructures. This model presents a physically motivated mechanism for the short-term RM variability observed in active repeaters. It demonstrates that such fluctuations can arise from wave-driven density cavitation within a broad, coupled parameter space involving wave amplitude, plasma density, and temperature, thereby characterizing the localized plasma dynamics required to produce the observed RM jitters.

Time-domain astrophysics is a rapidly growing field focused on the study of transient phenomena such as Gamma-Ray Bursts (GRBs), Fast Radio Bursts (FRBs), supernovae, novae, and AGN flares. Their characterization increasingly relies on a multi-messenger and multi-wavelength approach, combining gravitational waves, high-energy neutrinos, and electromagnetic observations across the spectrum. Such a coordinated strategy requires efficient information sharing and thus tools capable of rapidly compiling and contextualizing key data for each new event. We present Astro-COLIBRI, a well-established platform designed to meet this challenge. Astro-COLIBRI combines a public RESTful API, real-time databases, and a cloud-based alert system. It continuously listens to multiple alert streams, applies user-defined filters, and places each event in its multi-messenger and multi-wavelength context. Through its user-friendly interfaces, including a web application and mobile apps for iOS and Android, the platform provides clear data visualization as well as concise summaries of key event properties and observing conditions for user-defined locations.

We analyse Compton-thick active galactic nuclei (CT AGNs), a heavily obscured subclass that challenges traditional X-ray diagnostics. Using 243 sources from the 70-Month \textit{SWIFT}/BAT catalogue (26 CT, 217 non-CT), we investigate their properties across radio, infrared (IR), optical, and X-ray bands. VLASS data reveals slightly higher 2--3~GHz mean luminosities in CT AGNs, suggesting active cores attenuated by circumnuclear absorption. Mid-IR diagnostics show redder $W3-W4$ colours in CT AGNs, tracing cooler dust, with significant scatter likely driven by host-galaxy dilution. Most CT AGNs fall outside standard WISE selection wedges, highlighting mid-IR selection limitations. BPT diagnostics show that CT AGNs primarily occupy Seyfert regions, indicating isotropic narrow-line properties. CT AGNs favour significantly higher Eddington ratios ($\lambda_{\text{Edd}}$), supporting radiation-driven unification where intense accretion maintains high-column density. We also observe a moderate anti-correlation between [NII]/H$\alpha$ and $\lambda_{\text{Edd}}$. Principal component analysis identifies ionizing power and the accretion-obscuration link as primary variance drivers, though both populations overlap significantly in the PC1--PC2 plane. Machine learning achieved high recall (0.80) using intrinsic X-ray luminosity, [OI]$\lambda$6300 and H$\alpha$ luminosities, and $W2-W3$ colour. This demonstrates the potential for multi-wavelength signatures to verify CT candidates in future deep surveys where X-ray data is limited. Overall, our findings suggest CT AGNs are driven by high obscuration and accretion rates rather than a simple orientation effect.

Almost every galaxy in the local Universe is observed to have a massive black hole in the centre. The properties of these black holes are observed to tightly correlate with those of their host galaxy which has been interpreted as coevolution regulated by black hole feedback. This coevolution spans most of cosmic history, as the first active black holes, so-called active galactic nuclei, are already observed as early as $z\sim10$. In this chapter, we lay out how we can find supermassive black holes, review what we know about the population of black holes and their host galaxies from observations, and summarise what we have learned about their coevolution across cosmic time from both observations and simulations.

The HyGAL Stratospheric Observatory for Infrared Astronomy (SOFIA) legacy program aims at characterizing the interstellar medium in the Milky Way using hydrides, [C II], and [O I] absorption lines with the 2.7 m SOFIA telescope toward twenty-five submillimeter-bright Galactic star-forming regions. As part of HyGAL, we investigated correlations among the known H$_2$ tracers -- CH and OH from SOFIA observations, and HCO$^+$ and CCH from ancillary absorption line data from ground-based telescopes. We also examined the abundance variation of neutral atomic oxygen, [O I], observed in absorption. CH, OH, HCO$^+$, and CCH all exhibit strong mutual correlations. OH in particular shows tight correlations with HCO$^+$ and CCH, reflecting their linked chemical and physical pathways. Column density ratios among these H$_2$ tracers are consistent with previous measurements in local diffuse clouds and remain uniform across Galactic environments and velocity intervals. The gas phase oxygen abundance relative to total hydrogen, $\langle X$(O)$\rangle=N$(O)/$N$(H$_{\rm total}$), is $(3.09\pm0.64)\times10^{-4}$, slightly below the elemental solar value but consistent with the previous observations measuring gas-phase abundances. We also find that $N$(HI) decreases toward the regions where the molecular fraction exceeds $f_{H_2}^N \sim 0.5$, marking the onset of the molecular phase. While the atomic oxygen abundance remains roughly constant, the abundances of OH, HCO$^+$, and CCH increase with the molecular fraction. Gas traced by the HCO$^+$ absorption corresponds to higher molecular fractions than that traced by HI and hydride ions, highlighting density variations in the diffuse-to-translucent ISM along different lines of sight.

We present a comprehensive study of the pulsating primary component of the long-period binary system RY Lep. The spectral energy distribution and the absence of detectable lines indicate that the companion is likely a white dwarf. Atmospheric parameters and chemical abundances were determined from a high-resolution spectrum obtained with the the Southern African Large Telescope (SALT). The spectroscopic analysis reveals an underabundance of iron-group elements and an enhancement of neutron-capture elements, including barium and europium, with an overall metallicity of [m/H]$\approx -0.4$. In the next step, we performed the first Fourier analysis of long-term photometric data from ASAS, SuperWASP, and TESS. In the TESS observations, we identify several additional frequencies not present in the ground-based data. The dominant frequency at 4.4415 d$^{-1}$ is identified as a radial mode, most likely the first radial overtone. Finally, seismic modeling of RY Lep was carried out by fitting the dominant mode together with the secondary frequency at 6.5991 d$^{-1}$, considering two possible identification for the latter: the third radial overtone or a dipole mode. Bayesian inference based on Monte Carlo simulations yields a stellar mass of $\sim 2.0 $M$_\odot$ and an age of $\sim 730$ Myr. All viable seismic models place RY Lep in the hydrogen shell-burning evolutionary phase, with a metallicity consistent with the spectroscopic determination.

We present PHANGS-H{\alpha}, a narrow-band imaging survey that maps H{\alpha} emission over a sample of 65 nearby massive star-forming galaxies. The data were obtained using the MPG-ESO 2.2-meter telescope at La Silla and the du Pont 2.5-meter telescope at Las Campanas Observatory, in the framework of the multi-wavelength cloud-scale (50-100 pc) resolution mapping of molecular gas and star formation conducted by the Physics at High Angular resolution in Nearby GalaxieS (PHANGS) collaboration. PHANGS-H{\alpha} complements the already published PHANGS-ALMA, PHANGS-MUSE, PHANGS-HST, and PHANGS-JWST surveys, providing an anchor point for the photometric and astrometric calibration of these datasets, as well as samples of H ii regions, and star formation rate maps for the bulk of the PHANGS sample. We present observations, data processing, and calibration of the PHANGS-H{\alpha} dataset, as well as the procedures used to derive emission-line fluxes from narrow-band imaging. A subset of galaxies with available spectroscopic Ha mapping from the PHANGS-MUSE survey allows for a detailed comparison with the narrow-band photometry presented here. This informs a series of best practices for the processing of narrow-band H{\alpha} imaging that we apply to the full dataset.

We study how environment affects the mass-metallicity relation (MZR) at $z=4$-$10$ using deep imaging and spectroscopy from the James Webb Space Telescope (JWST). Combining CEERS and JADES, we compile a sample of 225 galaxies with stellar masses, star-formation rates, and gas-phase metallicities. We characterize environment using the projected fifth-nearest-neighbour surface density, $\Sigma_{5}$, within $\Delta z=\pm0.25$. At $4.5<z<7$, we find that galaxies in dense regions are more metal-rich at fixed $M_\star$ by $\sim0.1$-0.2 dex, while the slopes of the MZR remain similar across environments. Including SFR increases the separation, suggesting more efficient chemical enrichment in overdense regions. Compared to the local $T_e$-based FMR, our full sample lies $\simeq0.2$-0.3 dex below the $z\sim0$ relation, with a smaller deficit in overdense environments. We also examine how metallicity relates to galaxy size using NIRCam-based effective radii. Metallicity increases weakly with size up to $R_e\sim1$ kpc and then flattens, with only a modest residual trend at fixed $M_\star$ and little environmental dependence. Using mass-weighted stellar ages at $5<z<10$, we find a positive age-metallicity relation in both environments, steeper in the field. Finally, we find that the star-formation rate density is higher in overdense regions at $z\simeq6$-9 by a factor of $\sim2$-3. Overall, our results suggest that environment accelerates both star formation and chemical enrichment during the epoch of reionization. Future wide-area JWST spectroscopy, combined with ALMA and Euclid, will better constrain the role of environment in early galaxy evolution.

Defined as the magnetic field permeating cosmic voids, the Intergalactic Magnetic Field (IGMF) is thought to be a relic of the Big Bang, tracing a primordial magnetic seed at the origin of all astrophysical fields. Yet, it has thus far escaped detection. Lower limits on the IGMF strength can be established by observing very high-energy (VHE) photons from extragalactic sources. Specifically, this can be achieved by characterising the time-delayed secondary emission induced by highly energetic transient sources, such as gamma-ray bursts (GRBs). Most studies exclude values of the IGMF below $10^{-17}\;\mathrm{G}$ by comparing the expected effect to the sensitivity curves of various instruments in the $\mathrm{GeV}$ range or above. In this work, we simulate CTAO observation data under realistic observation conditions and perform spectral-temporal fits to estimate the constraints CTAO will bring on the IGMF once fully deployed. We apply the methodology to simulated sources with properties comparable to the few GRBs detected at VHE. In particular, we show that CTAO will probe strengths up to $\sim 10^{-15}\;\mathrm{G}$ when detecting sources similar to GRBs 221009A and 190114C. We also show that existing observations of GRB 221009A by the first CTAO Large Sized Telescope LST-1 favour a strength of $3\times 10^{-17}\;\mathrm{G}$.

We investigate the stability of a segmented deformable mirror (DM) on high-contrast testbeds and its impact on the images produced with coronagraphs. Segmented apertures are promising to obtain large primary mirrors for future missions with starlight suppression capabilities. Cophased at the sub-nanometer level, segments can be slightly misaligned by small drifts, proving harmful for exoplanet observations. We study the impact of misalignments on contrast using the High-contrast Imager for Complex Aperture Telescopes (HiCAT), a testbed which includes a 37-segment DM and produces coronagraphic images with 2.5e-8 contrast in narrowband light. Temporal wavefront errors due to the segmented DM are estimated with a Zernike wavefront sensor. Our in-lab results show aberrations at the sub-nanometer level, proving encouraging for contrast stability studies. We then use a digital twin of HiCAT to simulate coronagraphic images with an initial 0.5e-8 contrast and the segments in flat position. By injecting known perturbations on the segments, we observe a contrast degradation by a factor of 2.5, nearly corresponding to the typical contrast observed on HiCAT. These results highlight the importance of segment cophasing sensing and control strategies to ensure the required contrasts for exo-Earth imaging with a large segmented aperture for the Habitable Worlds Observatory mission.

Mean-motion resonances are expected to frequently arise at the inner edges of protoplanetary disks, where planet-disk interactions facilitate large-scale orbital convergence. Under certain conditions, however, the same dissipative forces that promote resonant capture can drive resonant librations overstable, ultimately breaking commensurabilities. Here we examine the onset of overstability near disk torque reversals and show that it can be subdued when the transition is sufficiently sharp. Adopting the dissipative circular restricted three-body problem as a paradigm, we present a WKB-style analysis that reduces the resonant dynamics to a damped, driven harmonic oscillator. Within this framework, we obtain an effective frictional term that is proportional to the local migration-rate gradient, parameterized by a dimensionless coefficient $\beta$ that encodes the steepness of the local torque reversal. Our analytical theory predicts that overstability is quenched once $\beta \gtrsim \tau_a/\tau_e$, where $\tau_a$ and $\tau_e$ denote the characteristic disk-driven evolution timescales of semi-major axis and eccentricity. We verify and refine our analytic results with direct $N$-body integrations. Simple estimates based on conventional type-I scalings suggest that the competition between overstability and its mitigation at disk inner edges is a borderline outcome that is sensitive to the detailed structure of planet-disk interactions.

The interaction between the LMC and SMC (the Clouds) has resulted in prominent tidal features, including an extended bridge of gas and stars connecting the two galaxies. This Bridge has likely formed during the most recent interaction between the Clouds, about 150-250 Myr ago. While some young stars observed in the Bridge have formed in-situ from the tidally stripped gas, stellar populations may also have been drawn out of the SMC during the tidal interaction. We aim to identify a clean sample of likely Bridge stars in the region between the LMC and SMC using Gaia DR3 astrometric and photometric data combined with machine-learning techniques. We use the dimensionality-reduction algorithm UMAP to construct a training sample of young stars in the outskirts of the SMC and LMC. A neural network trained on this sample is then applied to Gaia sources in the inter-Cloud region to classify the stars and identify candidate Bridge members. We present and characterise a new sample of young candidate Bridge stars, selected from Gaia DR3. We investigate its spatial distribution, kinematic properties and colour-magnitude diagram and validate it using existing Bridge samples. The young stellar Bridge aligns well with HI gas, clusters, and cepheid samples, apart from a small offset near the LMC outer disc. We measure a Bridge length of ~15 kpc and the stars are travelling from the SMC to the LMC at a median tangential velocity of ~114 km/s. This implies a crossing time of ~125 Myr, which is within the timeframe of the last interaction of the Clouds and therefore supports tidal stripping as a possible formation scenario of the Bridge.

Pebble accretion offers an efficient pathway to form planets, driven by a constant supply of inward drifting mass and an accretion efficiency enhanced by gas drag. While most studies assume a single pebble size (monodisperse), real discs contain a range of sizes (polydisperse), that drift, interact, and accrete at different rates. We aim to model polydisperse pebble accretion with a fluid approach, validating the method and exploring how gas disc evolution, solid-to-gas back-reaction, and a polydisperse size distribution affect growth. We use FARGO3D, modified to allow pebble accretion, to run 2D hydrodynamic simulations in a global disc with multiple dust/pebble species representing an underlying continuous pebble size distribution. With our framework of a multifluid approach, we have found values for pebble accretion efficiency consistent with earlier studies for a static gas disc. This confirms that our approach gives an accurate representation of pebble accretion. Evolving the gas disc we find lower efficiencies compared to an unperturbed gas disc for high Stokes number ($\gtrsim 0.3$) and higher efficiency for smaller St ($\lesssim0.3$). This effect is increased for higher planet masses. The accretion rate is mostly dominated by the highest Stokes numbers in our parameter study ($\mathrm{St}\in[10^{-2},10^0]$). The ratio we find between polydisperse and monodisperse pebble accretion rate is higher than previous estimations. We have constructed a multifluid model framework capable of accurately simulating polydisperse pebble accretion consistent with previous studies. This framework has advantages for simulating higher planet masses, as well as modelling multiple pebble species which are coupled to the gas. We find the perturbation of the protoplanet on the gas-disc lowering accretion rate when assuming a MRN-distribution of solids.

We statistically quantified the prevalence and properties of substructure in optical galaxy clusters and directly investigated its impact on X-ray morphology and scaling relations, leveraging new data from the DECaLS Legacy Survey and the SRG/eROSITA all-sky survey. We applied the hierarchical density-based clustering algorithm HDBSCAN to the redMaPPer galaxy cluster catalog to identify and characterize substructure from the probabilistic membership assignments. We then cross-matched this sample with the eROSITA X-ray morphology catalog to correlate optical substructure with a comprehensive set of X-ray morphological parameters. Finally, we analyzed the scaling relation between X-ray luminosity and optical richness for clusters with and without substructure. Substructure is a common feature, present in approximately 40% of clusters; a quarter of the full sample exhibits a fractional contribution to richness in excess of 35%. We find a highly significant correlation between optical substructure and disturbed X-ray morphologies, a trend that is strongest for high-mass clusters. The clusters with substructure also drive a stronger redshift evolution in the scatter of the Lx-lambda relation. At low redshifts (z<0.2), they display a systematically higher X-ray luminosity at fixed richness compared to relaxed systems. We attribute the enhanced effect of mergers on X-ray properties at low redshifts to the increased density contrast of low-redshift cool cores and longer substructure survival times, which are possibly due to the suppression of disruptive mixing by effects such as magnetic draping. At lower cluster richness, a discordance between X-ray morphology and the merging state indicates a growing relative importance of active galactic nucleus feedback in governing X-ray morphology.

While Earth locks much of its carbon in its crust as carbonates, Venus retains a comparable carbon inventory almost entirely in its atmosphere as CO$_2$. On Earth, the geological carbon cycle that has produced this vast crustal carbonate inventory is regulated by biology, liquid water, and plate tectonics, which together have stabilised climate over geological timescales. Venus presently lacks all these processes. We test whether Venus's massive CO$_2$ atmosphere is diagnostic of a specific evolutionary pathway by quantifying three routes: primary magma-ocean outgassing, secondary volcanic degassing in a stagnant-lid regime, and remobilisation of crustal carbonates after climate destabilisation. Using a coupled climate--weathering framework, we find that a past habitable Venus could have stored $\sim$20 bar of CO$_2$ as crustal carbonates. Following transition to runaway conditions, crustal heating releases this reservoir over tens of Myr. In stagnant-lid secondary-degassing models with a MORB-like mantle, outgassing reaches only $\sim$25 bar CO$_2$, limited by progressive mantle volatile depletion. However, Venus-like inventories can be achieved through: (i) magmatic carbon enrichment, (ii) increased magmatic delivery to the surface (high extrusion or melt production), and (iii) the recycling of undegassed carbon back into the planet's interior. Primary magma-ocean outgassing can generate $>10^2$ bar CO$_2$, but the retained fraction after early escape remains uncertain. Ultimately, a Venus-like massive CO$_2$ atmosphere is an equifinal outcome and does not uniquely diagnose a temperate past.

I perform a model-independent reconstruction of the background pre-recombination expansion history of the Universe. I find that purely early-time resolutions to the Hubble tension, satisfying the geometric CMB constraints, exist at the background level. This class of solutions requires a smooth transition around matter-radiation equality, characterized by a $\simeq 15\%$ expansion rate enhancement prior to recombination. This result serves as a blueprint for future model-building approaches, providing a background stress-test for Hubble tension proposals.

The streaming instability and pebble accretion are two physical mechanisms with demonstrated potentials to drive, respectively, the formation of planetesimals and the growth of planetary systems containing a diverse range of planetary types. Here we explore the protoplanetary disc conditions in terms of turbulence strength, Stokes number and initial disc size that are needed to (i) form planetesimals by the streaming instability, (ii) form gas giant planets in cold orbits, (iii) form super-Earths and sub-Neptunes close to the star and (iv) form rocky planet embryos in temperate orbits. We identify an optimum Stokes number range between St= 0.01 and St= 0.03 where all three planetary classes form and where the streaming instability is triggered for a slightly elevated pebble metallicity. Cold gas giants require a turbulence strength of at most $\delta=10^{-4}$ and furthermore need large initial disc sizes to benefit from a prolonged pebble flux; super-Earths and rocky planet embryos tolerate higher turbulence strengths similar to those measured for the vertical shear instability. A higher Stokes number of St=0.1 is detrimental to the formation of cold gas giants due to the short-lived pebble flux. For Stokes numbers below St= 0.003, extremely low values of turbulence ($\delta<10^{-5}$) are required to form cold gas giants. We highlight how loss of gas to disc winds, reduction in the migration speed by thermal or dynamical torques or the presence of pressure bumps in the outer disc could increase the parameter space for the formation of cold gas giants. We derive analytically that the mass of the largest planetesimals formed by the streaming instability is of similar magnitude to the threshold mass beyond which pebble accretion becomes efficient, if planetesimals form in the earliest phases of protoplanetary disc evolution.

The dispersion of fast radio bursts (FRBs) measures the column density of free electrons, tracing the diffuse ionized gas that contains more than $90\%$ of all baryons. On linear scales the FRB dispersion field is an approximately unbiased tracer of the matter distribution, an idea long assumed in the FRB large-scale structure literature and recently formalized by Zhou and Zhang [arXiv:2510.11022]. This follows from baryon-mass conservation, which forces the total baryon field to have unit linear bias, with dispersion inheriting this bias up to small corrections from the stellar and neutral-gas components. We show these corrections can be bounded at the percent level using existing galaxy and 21 cm surveys, and confirm with the FLAMINGO hydrodynamical simulations that the electron bias varies at the percent level across a wide range of feedback prescriptions. The dispersion-galaxy cross-power spectrum at linear scales directly constrains $B_8 \equiv \sigma_8(\Omega_b/0.05)^{1/2}$, a baryonic analog of $S_8$, independently of feedback physics. Because most of the per-object variance in dispersion is cosmological signal rather than noise, $\sim\!10^5$ localized FRBs can match the statistical power of $\sim\!10^8$ weak-lensing galaxy shape measurements. FRB dispersion thus joins weak lensing and redshift-space distortions as a new unbiased tracer of matter on large scales.

Multi-wavelength observations of molecular and ionized gas indicate that GMCs are short-lived, generally dispersing within one or two dynamical timescales. To investigate the physical origin of these short lifetimes and the role of star formation prescriptions, we conduct radiation-hydrodynamic simulations of an NGC 300-like disk galaxy with RAMSES-RT. We compare two distinct star formation models, one based on a local gravo-thermo-turbulent (GTT) condition and the other employing sink particles, to examine how star formation and feedback collectively regulate GMC evolution. The sink-particle-based model yields bursty yet self-regulated global star formation rates of $0.1$-$0.5$ $M_{\odot}\,yr^{-1}$ and produces GMC lifetimes of $\sim20$-$30$ Myr, with star formation efficiencies (SFEs) per free-fall time of a few percent, consistent with observations. In contrast, the GTT model generates a population of long-lived clouds with lifetimes $\gtrsim200$ Myr, owing to the extremely low SFEs per free-fall time $(\lesssim3\times10^{-3})$, which renders stellar feedback ineffective. With both models, cloud-cloud mergers extend the lifetimes of GMCs and increase their integrated SFEs by lengthening the star-forming duty cycle, while having only a minor impact on instantaneous efficiencies. On galactic scales, both models broadly reproduce the observed KS relation within its scatter, yielding gas depletion times of a few Gyr. In comparison, an extreme feedback model with the supernova energy boosted by a factor of five, combined with the GTT star formation model, excessively suppresses star formation and produces much longer depletion times ($6$-$20$ Gyr) for this isolated system. These results demonstrate that GMC lifecycles are strongly governed by the adopted star formation model, highlighting the need for improved prescriptions that realistically capture clump-scale star formation.

We present 2D and 3D Particle-in-Cell simulations of driven collisionless magnetic reconnection triggered by the compression and merger of two Lundquist-type force-free flux tubes in a strongly magnetized pair plasma, with a focus on magnetic energy dissipation and particle acceleration. We show that 3D effects systematically delay the onset of reconnection in comparison with equivalent 2D runs, an effect further enhanced by a strong guide field, due to reduced linear growth rates and phase decoherence of oblique modes. Increasing the external drive accelerates both tearing and drift-kink instabilities, while a strong guide field suppresses coherent drift-kink activity and has a comparatively mild impact on tearing. Despite these differences in early-time dynamics, all simulations enter a fast-merging phase characterized by a normalized reconnection rate 0.08--0.10, coinciding with a transient reduction of the guide-to-reconnecting field ratio inside the current sheet. The high-energy cutoff of accelerated particles converges to a common asymptotic value, gamma_cut/sigma_in ~ 50, with only a weak dependence on the driving strength. This behavior is consistent with an electric-field-limited acceleration process, in which the maximum energy is set by the reconnection electric field and the duration of the energization phase. The resulting nonthermal particle spectra are similar across all runs, with power-law indices p ~ 1.6--2.0.

We present a unified analysis of the linear evolution of peculiar-velocity perturbations in the distribution of pressureless matter after recombination. Our study is carried out within the framework of full general relativity and encompasses both the earlier Einstein-de Sitter epoch and the subsequent $\Lambda$-dominated phase. Starting from a non-interacting, non-comoving mixture of radiation and dust, we derive the generalized differential equations governing the evolution of these velocity perturbations. We confirm that linear peculiar velocities ($v$) grow as $v\propto t$ throughout the Einstein-de Sitter era. In contrast, during a later phase of increasing $\Omega_{\Lambda}$-contribution, we find that the growth of the peculiar-velocity field is progressively suppressed, before reversing to decay. Nevertheless, part of the earlier velocity growth persists to the present. Hence, bulk-flow velocities at intermediate redshifts are expected to exceed those predicted by the $\Lambda$CDM model, followed by a decline in their value at lower redshifts. Interestingly, such peculiar-velocity profiles have already been reported in the literature.

We present case studies of two impulsive solar energetic electron (SEE) events during which particles at energies from 1-600 keV were detected by THEMIS-ARTEMIS orbiting the Moon, Wind at Earth's first Lagrange point, and (for one event) STEREO-A located at 1 AU, off the Sun-Earth line. The SEEs were initially highly anisotropic, traveling outward along the magnetic field with distinct energy-time dispersion. For one event, the spectra contained inverse velocity dispersion (IVD) signatures, whereby electrons at intermediate energies arrived to the spacecraft before those at higher energies. Similar features were recently discovered within 1 AU for energetic protons; this represents the first IVD detection for energetic electrons at Earth's orbital distance. During both events, a second beam of counter-streaming electrons was detected after a short time. Based on the time-delay in the detections at various energies, the path traveled by these counter-streaming electrons was on the order of 1-2 AU. We show that an interplanetary coronal mass ejection (ICME) passed the spacecraft a few days prior to the onset of each event and was located beyond 1 AU when the SEEs were detected, suggesting that the electrons were part of the same population, but reflected off the shock front of these precursor ICMEs. In the context of solar system exploration, this represents an unidentified hazard for astronaut safety beyond low-Earth orbit: although the initial phase of impulsive SEE events typically stream anti-Sunward, ICMEs located beyond Earth provide a mechanism for hazardous particles to travel Sunward during extreme events.

We have used new magnetotelluric data collected in the Curnamona Province and the adjacent part of the Delamerian Orogen margin to image electrical conductivity structures and to inform the understanding of the crustal architecture within the regional geological context. The preferred 3D resistivity model confirms, and resolves in greater detail, crustal-scale conductive features that have been mapped by the long-period data collected at half-degree spacing as part of the Australian Lithospheric Architecture Magnetotelluric Project (AusLAMP), that is, the prominent Curnamona Province Conductor and the two Nackara Arc conductors. The new model reveals that the eastern Nackara Arc (ENAC) conductor continues as the Broken Hill Conductor (BHC) into the Curnamona Province. Regional geological considerations suggest that its formation is possibly linked to rifting/extension in the early Cambrian. Although we recognise that the east-west trending Wilcannia Conductor could be a possible continuation of the ENAC-BHC zone, integration with recently acquired deep seismic reflection data and evaluation of the geological setting lead us to suggest that they are not genetically linked. We suggest that the Wilcannia Conductor is younger and most likely is related to late Delamerian (~500 Ma) or Siluro-Devonian magmatism. Finally, these conductivity anomalies may represent large-scale trans-crustal structures that control the emplacement of low volume alkaline ultramafic magmas, and show a spatial relationship with certain mineral deposit types, suggesting a possible control on the distribution and formation of metallogenic provinces/belts in the region. This will be further investigated in future work.

Low-latency gravitational-wave search pipelines provide early-warning alerts for multimessenger astrophysical transients. Current pipelines whiten the data stream using acausal, linear-phase filters, which require a look-ahead buffer that introduces several seconds of algorithmic latency. Eliminating this latency requires causal, minimum-phase whitening filters using only past data. However, operating causal filters under non-stationary noise is non-trivial: the drifting power spectral density must be tracked without degrading the matched-filter signal-to-noise ratio (SNR), filter updates must preserve the minimum-phase condition, and the altered phase response must be compensated to maintain sky-localization accuracy. In Paper I we introduced a gauge theoretic signal processing framework and showed that the minimum-phase connection on the manifold of power spectra provides a geometrically exact update rule for causal filters. Here we validate that framework numerically and operationally, demonstrating that parallel transport along this connection strictly preserves the minimum-phase property while exactly conserving the matched-filter SNR. We numerically certify the flatness of this connection, showing that the optimal filter is a path-independent state function of the instantaneous noise. Through an injection campaign on O3 data with 15,347 binary black hole signals across the LIGO-Virgo network, we confirm that this architecture preserves the detection sensitivity and inter-detector timing and phase accuracy of the linear-phase baseline. Implementing the framework in the production sgnl pipeline reduces whitening latency by 1.0 s (33%) at a 4-second noise estimation cadence, confirmed in controlled tests and on live O3 replay data at production scale. Stride reduction experiments show that up to 91% of baseline trigger latency can be eliminated with sub-second pipeline cadence.

Radiometric inconsistencies remain a major challenge in generating seamless lunar mosaics from multi-mission orbital imagery due to variability in illumination geometry, sensor characteristics, and acquisition conditions. This paper presents a deep learning-based radiometric normalization framework for multi-mission lunar mosaics constructed primarily from ISRO's Chandrayaan-2 Terrain Mapping Camera (TMC) data, supplemented with auxiliary imagery from the SELENE (Kaguya) mission. The proposed approach employs a conditional generative adversarial network (cGAN) comprising a U-Net-based generator and a PatchGAN discriminator to learn a nonlinear radiometric mapping from conventionally mosaicked lunar imagery to a photometrically consistent reference derived from LROC Wide Angle Camera (WAC) data. A patch-based training strategy with overlap-aware inference is adopted to enable scalable processing of large-area mosaics while preserving structural continuity across tile boundaries. Quantitative evaluation using Structural Similarity Index (SSIM), Peak Signal-to-Noise Ratio (PSNR), and Root Mean Square Error (RMSE) demonstrates consistent improvements over traditional histogram-based normalization techniques. The proposed framework achieves enhanced tonal uniformity, reduced seam artifacts, and improved structural coherence across multi-source lunar datasets. These results highlight the effectiveness of learning-based radiometric normalization for large-scale planetary mosaicking and demonstrate its potential for generating high-fidelity lunar surface maps from heterogeneous orbital imagery.

We investigate the Wheeler-DeWitt equation for a flat, homogeneous, and isotropic Universe containing a canonical scalar field with a potential. We show that under the constraint $|\Psi|=1$, where the Wheeler-DeWitt equation exactly becomes the classical Hamilton-Jacobi equation, the form of the potential is completely determined depending on the value of the operator ordering parameter. Furthermore, we demonstrate that the classified potentials admit simple forms, such as the exponential, quadratic with a negative cosmological constant, and cosine-type potential with a negative cosmological constant. Several of these have already been explored in the context of inflation or dark energy. Finally, focusing on the system with the cosine-type potential and a negative cosmological constant in the classified potentials, we derive the analytical solutions for the scale factor and the scalar field and discuss the cosmological implications.

Agentic AI systems are increasingly being integrated into scientific workflows, yet their behavior under realistic conditions remains insufficiently understood. We evaluate CMBAgent across two workflow paradigms and eighteen astrophysical tasks. In the One-Shot setting, access to domain-specific context yields an approximately ~6x performance improvement (0.85 vs. ~0 without context), with the primary failure mode being silent incorrect computation - syntactically valid code that produces plausible but inaccurate results. In the Deep Research setting, the system frequently exhibits silent failures across stress tests, producing physically inconsistent posteriors without self-diagnosis. Overall, performance is strong on well-specified tasks but degrades on problems designed to probe reasoning limits, often without visible error signals. These findings highlight that the most concerning failure mode in agentic scientific workflows is not overt failure, but confident generation of incorrect results. We release our evaluation framework to facilitate systematic reliability analysis of scientific AI agents.

A K-mirror rotates the wavefront of an incident optical field. However, the rotation always introduces polarization changes in the transmitted field. This is a serious concern for applications ranging from astronomical image derotation to orbital angular momentum spectrum characterization in photonic quantum technology. Recent efforts have shown that the polarization change can be minimized significantly, but these require either a very small base angle that limits the field of view, or mirrors with a customized refractive index. Making the transmitted polarization state completely independent of the rotation angle has remained an open problem. In this work, we show that placing half-wave plates before and after a K-mirror and rotating them synchronously at half the K-mirror rotation angle makes the polarization change in the transmitted field exactly independent of the rotation angle. This works for any wavefront rotator, any base angle, any mirror refractive index, and any input state of polarization. We experimentally demonstrate the approach using a K-mirror with a base angle of $30^{\circ}$, which gives the largest field of view among practical designs, and find a mean polarization error of ~1%, limited only by the retardance imperfection of commercially available half-wave plates. This has significant practical implications for applications that require precise wavefront rotation without polarization change.

In dense neutrino gas, pairing correlations between neutrinos and antineutrinos with opposite momenta can be nonzero in generalized neutrino quantum kinetic equations at the mean-field level. In this Letter, we investigate for the first time the condition under which collective neutrino-antineutrino ($\nu\bar\nu$) pairing instabilities can occur, using simplified toy models consisting of discretized $\nu\bar\nu$ pairs in a homogeneous neutrino gas. We find that, in ansiotropic systems, $\nu\bar\nu$ pairing instabilities generally emerge when the phase space distribution of the excessive pair-occupation number, defined as the sum of the neutrino and antineutrino occupation numbers of a pair minus 1, changes signs. The associated instability growth rate is set by the forward scattering potential and is comparable to that of collective fast neutrino flavor instabilities. The instabilities can result in pair conversions of $\nu\bar\nu$ occupation numbers between different momentum modes. Our results motivate further studies to assess the relevance of $\nu\bar\nu$ pairing effects in realistic astrophysical and cosmological environments.