astro-ph
astro-ph
11-26 00:00
arXiv:2511.19467v1 Announce Type: new Abstract: Measuring cometary nuclei is notoriously difficult because they are usually unresolved and embedded within bright comae, which hampers direct size measurements even with space telescopes. We present a practical, instrumental method that, stabilises the inner core through bicubic resampling, performs forward point-spread function PSF+convolution, and separates the unresolved nucleus from the inner-coma profile via an explicit Dirac Delta function added to a Rho^-1 surface brightness law. The method yields the nucleus flux by fitting an azimuthal averaged profile with two amplitudes only PSF core and convolved coma, with transparent residual diagnostics. As a case study, we apply the workflow to the interstellar comet 3I/ATLAS alias C/2025 N1, incorporating Hubble Space Telescope constraints on the nucleus size. We find that radius solutions consistent with 0.16 <= Rn <= 2.8 km for Pv = 0.04 are naturally recovered, in line with the most recent HST upper limits. The approach is well-suited for survey pipelines Rubin LSST and targeted follow up.
astro-ph.srastro-ph.epastro-ph.im
astro-ph
astro-ph
11-26 00:00
arXiv:2511.19505v1 Announce Type: new Abstract: Spacecraft equipped with multiple propulsion modes or systems can offer enhanced performance and mission flexibility compared with traditional configurations. Despite these benefits, the trajectory optimization of spacecraft utilizing such configurations remains a complex challenge. This paper presents a sequential convex programming (SCP) approach for the optimal design of multi-mode and multi-propulsion spacecraft trajectories. The method extends the dynamical linearization within SCP using sparse automatic differentiation, enabling efficient inclusion of multiple propulsion modes or systems without complex manual reformulation while maintaining comparable computational efficiency. New constraint formulations are introduced to ensure selection of a single propulsion mode at each time step and limit the total number of modes used. The approach is demonstrated for (i) a low-thrust Earth-67P rendezvous using the SPT-140 thruster with 20 discrete modes, and (ii) an Earth-Mars transfer employing both a low-thrust engine and a solar sail. Results confirm that the proposed method can efficiently compute optimal trajectories for these scenarios.
astro-ph.epastro-ph.imcs.syeess.sy
astro-ph
astro-ph
11-26 00:00
arXiv:2511.19572v1 Announce Type: new Abstract: Binaries that host a carbon-rich Wolf-Rayet (WC) star and an OB-type companion can be copious dust producers. Yet the properties of dust, particularly the grain size distribution, in these systems remain uncertain. We present Band 6 observations of WR 112 by the Atacama Large Millimeter/submillimeter Array telescope (ALMA), which are the first millimeter observations of a WC binary system capable of resolving its dust emission. By combining ALMA observations with James Webb Space Telescope (JWST) images, we were able to analyze the spatially resolved spectral energy distribution (SED) of WR 112. We found that the SEDs are consistent with emissions from hydrogen-poor amorphous carbon grains. Notably, our results also suggest that the majority of grains in the system have radii below one micrometer, and the extended dust structures are dominated by nanometer-sized grains. Among four parameterizations of the grain radius distribution that we tested, a bimodal distribution, with abundant nanometer-sized grains and a secondary population of 0.1-micron grains, best reproduces the observed SED. This bimodal distribution helps to reconcile the previously conflicting grain size estimates reported for WR 112 and for other WC systems. We hypothesize that dust destruction mechanisms such as radiative torque disruption and radiative-driven sublimation are responsible for driving the system to the bimodal grain size distribution.
astro-ph.srastro-ph.epastro-ph.ga
astro-ph
astro-ph
11-26 00:00
arXiv:2511.19588v1 Announce Type: new Abstract: CD-35 2722 B is an L dwarf companion to the nearby, $\sim 50-200$ Myr old M1 dwarf CD-35 2722 A. We present a detailed analysis of both objects using high-resolution ($R \sim 35,000$) $K$ band spectroscopy from the Keck Planet Imager and Characterizer (KPIC) combined with archival photometry. With a mass of $30^{+5}_{-4} M_{\mathrm{Jup}}$ (planet-to-host mass ratio 0.05) and projected separation of $67\pm4$ AU from its host, CD-35 2722 B likely formed via gravitational instability. We explore whether the chemical composition of the system tells a similar story. Accounting for systematic uncertainties, we find $\mathrm{[M/H]}=-0.16^{+0.03}_{-0.02} \mathrm{(stat)} \pm 0.25 \mathrm{(sys)}$ dex and $^{12}\mathrm{C}/^{13}\mathrm{C}=132^{+20}_{-14}$ for the host, and $\mathrm{[M/H]}=0.27^{+0.07}_{-0.06} (\mathrm{stat}) \pm 0.12 (\mathrm{sys})$ dex, $^{12}\mathrm{CO}/^{13}\mathrm{CO}=159^{+33}_{-24} \mathrm{(stat)}^{+40}_{-33} \mathrm{(sys)}$, and $\mathrm{C/O} = 0.55 \pm 0.01 (\mathrm{stat}) \pm 0.04 (\mathrm{sys})$ for the companion. The chemical compositions for the brown dwarf and host star agree within the $1.5\sigma$ level, supporting a scenario where CD-35 2722 B formed via gravitational instability. We do not find evidence for clouds on CD-35 2722 B despite it being a photometrically red mid-L dwarf and thus expected to be quite cloudy. We retrieve a temperature structure which is more isothermal than models and investigate its impact on our measurements, finding that constraining the temperature structure to self-consistent models does not significantly impact our retrieved chemical properties. Our observations highlight the need for data from complementary wavelength ranges to verify the presence of aerosols in likely cloudy L dwarfs.
astro-ph.srastro-ph.ep
astro-ph
astro-ph
11-26 00:00
arXiv:2511.19595v1 Announce Type: new Abstract: We present new state-of-the-art lens models for strong gravitational lensing systems from the Sloan Lens ACS (SLACS) survey, developed within a Bayesian framework that employs high-dimensional (pixellated), data-driven priors for the background source, foreground lens light, and point-spread function (PSF). Unlike conventional methods, our approach delivers high-resolution reconstructions of all major physical components of the lensing system and substantially reduces model-data residuals compared to previous work. For the majority of 30 lensing systems analyzed, we also provide posterior samples capturing the full uncertainty of each physical model parameter. The reconstructions of the background sources reveal high significance morphological structures as small as 200 parsecs in galaxies at redshifts of z 0.5-1.0, demonstrating the power of strong lensing and the analysis method to be used as a cosmic telescope to study the high redshift universe. This study marks the first application of data-driven generative priors to modeling real strong-lensing data and establishes a new benchmark for strong lensing precision modeling in the era of large-scale imaging surveys.
astro-ph.coastro-ph.gaastro-ph.im
astro-ph
astro-ph
11-26 00:00
arXiv:2511.19600v1 Announce Type: new Abstract: The elevated UV luminosity functions (UVLF) from recent James Webb Space Telescope (JWST) have challenged the viability of existing theoretical models. To address this, we use a semi-analytical framework -- which couples a physically motivated source model derived from radiative-transfer hydrodynamic simulations of reionization with a Markov Chain Monte Carlo sampler -- to perform a joint calibration to JWST galaxy surveys (UVLF, $\phi_{\rm UV}$ and UV luminosity density, $\rho_{\rm UV}$) and reionization-era observables (ionizing emissivity, $\dot{N}_{\rm ion}$, neutral hydrogen fraction, $x_{\rm HI}$, and Thomson optical depth, $\tau$). We find that models with weak feedback and a higher contribution from faint galaxies reproduce the reionization observables but struggle to match the elevated JWST UVLF at $z > 9$. In contrast, models with stronger feedback (i.e., rapid redshift evolution) and a higher contribution from bright galaxies successfully reproduce JWST UVLF at $z \geq 10$, but over-estimate the bright end at $z < 9$. The strong-feedback model constrained by JWST UVLF predicts a more gradual and extended reionization history, as opposed to the sudden reionization seen in the weak-feedback models. This extended nature of reionization ($z\sim 16$ - $6$) yields an optical depth consistent (at 2-$\sigma$) with the Cosmic Microwave Background (CMB) constraint, thereby alleviating the photon-budget crisis. In both scenarios, reionization is complete by $z \sim 6$, consistent with current data. Our analysis highlights the importance of accurately modeling feedback and ionizing emissivities from different source populations during the first billion years after the Big Bang.
astro-ph.coastro-ph.ga
astro-ph
astro-ph
11-26 00:00
arXiv:2511.19602v1 Announce Type: new Abstract: Understanding black hole-galaxy co-evolution and the role of AGN feedback requires complete AGN samples, including heavily obscured systems. In this work, we present the first UV line-selected ([Nev]3426 and CIV1549) sample of obscured AGN with full X-ray-to-radio coverage, assembled by combining data from the Chandra COSMOS Legacy survey, the COSMOS2020 catalogue, IR photometry from XID+, and radio observations from the VLA and MIGHTEE surveys. Using CIGALE to perform spectral energy distribution (SED) fitting, we analyse 184 obscured AGN at 0.6 < z < 1.2 and 1.5 < z < 3.1, enabling detailed measurements of AGN and host galaxy properties, and direct comparison with SIMBA hydrodynamical simulations. We find that X-ray and radio data are essential for accurate SED fits, with the radio band proving critical when X-ray detections are missing or in cases of poor IR coverage. Comparisons with matched non-active galaxies and simulations suggest that the [NeV]-selected sources are in a pre-quenching stage, while the CIV-selected ones are likely quenched by AGN activity. Our results indicate that [NeV] and CIV selections target galaxies in a transient phase of their co-evolution, characterised by intense, obscured accretion, and pave the way for future extensions with upcoming large area high-z spectroscopic surveys.
astro-ph.heastro-ph.ga
astro-ph
astro-ph
11-26 00:00
arXiv:2511.19603v1 Announce Type: new Abstract: The enrichment history of galaxy clusters and groups remains far from being fully understood. Recent measurements in massive clusters have revealed remarkably flat iron abundance profiles out to the outskirts, suggesting that similar enrichment processes have occurred for all systems. In contrast, abundance profiles in galaxy groups have sometimes been measured to decline with radius, challenging our understanding of the physical processes at these scales. In this paper, we present a pilot study aimed at accurately measuring the iron abundance profiles of MKW3s, A2589, and Hydra A, three poor clusters with total masses of $M_{500} \simeq 2.0-2.5 \times 10^{14}$ M$_\odot$, intermediate between the scales of galaxy groups and massive clusters. Using XMM-Newton to obtain nearly complete azimuthal coverage of the outer regions of these systems, we show that abundance measurements in the outskirts are more likely to be limited by systematics than by statistical errors. In particular, inaccurate modelling of the soft X-ray background can significantly bias metallicity estimates in regions where the cluster emission is faint. Once these systematics are properly accounted for, the abundance profiles of all three clusters appear to be flat at $Z \sim 0.3$ Z$_{\odot}$, in agreement with values observed in massive clusters. Using available stellar mass estimates, we also computed their iron yields, thereby beginning to probe a largely unexplored mass range. We find $Y_{Fe,500} = 2.68\pm0.34$, $2.54\pm0.64$, and $7.51\pm1.47$ Z$_{\odot}$ for MKW3s, A2589, and Hydra A, respectively, spanning the transition regime between galaxy groups and massive clusters. Future observations of systems with temperatures of $2-4$ keV will be essential to further populate this intermediate-mass regime and to draw firmer conclusions on the chemical enrichment history of galaxy systems across the full mass scale.
astro-ph.coastro-ph.ga
astro-ph
astro-ph
11-26 00:00
arXiv:2511.19614v1 Announce Type: new Abstract: The translation from direct observables to physical properties of galaxies is a key step in reconstructing their evolutionary histories. Variations in stellar populations and star-dust geometry can induce inhomogeneous mass-to-light ratios, complicating this process. SE3D is a novel modelling framework, built around a radiative transfer emulator, aimed at tackling this problem. In this paper, we test the ability of SE3D to recover known intrinsic properties of toy model and TNG50 simulated galaxies from mock observations of their multi-wavelength photometric and structural properties. We find an encouraging performance for several key characteristics, including the bulk stellar mass, dust mass and SFR, as well as their respective radial extents. We point out limitations, and investigate the impact of various sources of model mismatch. Among them, mismatch in the shapes of star formation histories contributes most, with radial and azimuthal structure and stellar metallicity distributions playing a progressively more minor role. We also analyse the evolution from z=2 to z=0 of resolved stellar and dust properties of TNG galaxies, as measured intrinsically and expressed in their distribution across UVJ and IRX-$\beta$ diagnostic diagrams. We test different methods to assign dust to the simulation, and find a persistent lack of Mdust/Mstar evolution and a more limited dynamic range across the diagnostic diagrams compared to observations.
astro-ph.gaastro-ph.im
astro-ph
astro-ph
11-26 00:00
arXiv:2511.19615v1 Announce Type: new Abstract: We implement the constrained divergence cleaning algorithm of \citet{Tricco2016} into the cosmological smoothed particle magnetohydrodynamics (SPMHD) code OpenGadget3. Our implementation modifies the governing equations of SPMHD to allow the constrained hyperbolic/parabolic cleaning scheme to be applied consistently in an expanding cosmological framework. This ensures that divergence errors in the magnetic field are actively propagated away and damped, rather than merely being advected with the flow or partially controlled by source terms. To validate our implementation, we perform a series of standard test problems, including the advection of divergence errors, the Orszag-Tang vortex, the Brio-Wu shock tube, and magnetised Zeldovich pancakes. These tests confirm that our scheme successfully reduces divergence errors while preserving the correct physical evolution of the system. We then apply the method to a fully cosmological simulation of a massive galaxy cluster, comparing the results to those obtained using the previously employed Powell eight-wave divergence preserving scheme. We find that the overall density structure of the cluster is largely unaffected by the choice of divergence cleaning method, and the magnetic field geometry and strengths in the cluster core remain similar. However, in the cluster outskirts ($r \approx$~1-3~$h^{-1}$~Mpc), the magnetic field is amplified by a factor of $\sim$ 5 compared to the Powell-only approach. Moreover, the constrained divergence cleaning algorithm reduces the divergence error by 2-3 orders of magnitude throughout the cluster volume, demonstrating its effectiveness in maintaining the solenoidal condition of the magnetic field in large-scale cosmological simulations. Our results suggest that accurate divergence control is essential for modeling magnetic field amplification in low-density regions of galaxy clusters.
astro-ph.coastro-ph.gaastro-ph.im
astro-ph
astro-ph
11-26 00:00
arXiv:2511.19620v1 Announce Type: new Abstract: We present the first detection of the cosmological 21 cm intensity mapping signal in auto-correlation at z ~ 1 with the Canadian Hydrogen Intensity Mapping Experiment (CHIME). Using 94 nights of observation, we have measured the 21 cm auto-power spectrum over a frequency range from 608.2 MHz to 707.8 MHz (z = 1.34 to 1.01) at 0.4 h Mpc^-1 < k < 1.5 h Mpc^-1, with a detection significance of 12.5 sigma. Our analysis employs significant improvements to the CHIME data processing pipeline compared to previous work, including novel radio frequency interference (RFI) detection and masking algorithms, achromatic beamforming techniques, and foreground filtering before time averaging to minimize spectral leakage. We establish the robustness and reliability of our detection through a comprehensive suite of validation tests. We also measure the 21 cm signal in two independent sub-bands centered at z ~ 1.08 and z ~ 1.24 with detection significance of 8.7 sigma and 9.2 sigma, respectively. We briefly discuss the theoretical interpretation of these measurements in terms of a power spectrum model, deferring the details to a companion paper. This auto-power spectrum detection demonstrates CHIME's capability to probe large-scale structure through 21 cm intensity mapping without reliance on external galaxy surveys.
astro-ph.coastro-ph.gaastro-ph.im
astro-ph
astro-ph
11-26 00:00
arXiv:2511.19623v1 Announce Type: new Abstract: We present a framework for analysing panchromatic and spatially resolved galaxy observations, dubbed SE3D. SE3D simultaneously and self-consistently models a galaxy's spectral energy distribution and its spectral distributions of global structural parameters: the wavelength-dependent galaxy size, light profile and projected axis ratio. To this end, it employs a machine learning emulator trained on a large library of toy model galaxies processed with 3D dust radiative transfer and mock-observed under a range of viewing angles. The toy models vary in their stellar and dust geometries, and include radial stellar population gradients. The computationally efficient machine learning emulator uses a Bayesian neural network architecture, and reproduces the spectral distributions at an accuracy of ~ 0.05 dex or less across the dynamic range of input parameters, and across the rest-frame UVJ colour space spanned by observed galaxies. We carry out a sensitivity analysis demonstrating that the emulator has successfully learned the intricate mappings between galaxy physical properties and direct observables (fluxes, colours, sizes, size ratios between different wavebands, ...). We further discuss the physical conditions giving rise to a range of total-to-selective attenuation ratios, Rv, with among them most prominently the projected dust surface mass density.
astro-ph.gaastro-ph.im
astro-ph
astro-ph
11-26 00:00
arXiv:2511.19646v1 Announce Type: new Abstract: Planetary atmospheric energy budgets primarily depend on stellar incident flux. However, stellar variability can have major consequences for the evolution of planetary climates. In this work, we evaluate how stellar variability influences the equilibrium temperature and water retention of planets within the Habitable Zone (HZ). We present a sample of 9 stars that are known to host at least one planet within the HZ and that were identified to have a variability amplitude exceeding 100 ppm based on photometry from the Transiting Exoplanet Survey Satellite (TESS). We investigate the effect that the variability of these stars have on the insolation flux of their HZ planets and the resulting changes in the induced planetary equilibrium temperature. Our results show that for the stars in our sample, the stellar variability has an insignificant effect on the equilibrium temperature of HZ planets. However, we also emphasize that these stars are not representative of more extreme variable stars, since exoplanets are more difficult to detect and characterize in the presence of extreme variability. We also investigate the equilibrium temperature and long-term evolution of a hypothetical Earth-like planet placed at the inner edge of the HZ around a highly variable star. We found that the water loss rates are comparable between both variable and quiet host stars for Earth-like planets in the inner HZ. Overall, these results broaden our knowledge on the impact of stellar variability on planetary habitability.
astro-ph.srastro-ph.ep
astro-ph
astro-ph
11-26 00:00
arXiv:2511.19508v1 Announce Type: new Abstract: Primordial Magnetic Fields (PMFs) -- magnetic fields originating in the early Universe and permeating the cosmological scales today -- can explain the observed microGauss-level magnetisation of galaxies and their clusters. In light of current and upcoming all-sky radio surveys, PMFs have drawn attention not only as major candidates for explaining the large-scale magnetisation of the Universe, but also as potential probes of early-Universe physics. In this paper, using cosmological simulations coupled with light-cone analysis, we study for the first time the imprints of the PMF structure on the mean rotation measure (RM) originating in the intergalactic medium (IGM), $\langle \mathrm{RM_{IGM}}\rangle$. We introduce a new method for producing full-sky $\mathrm{RM_{IGM}}$ distributions and analyse the autocorrelation of $\mathrm{RM_{IGM}}$ on small and large angular scales; we find that PMF structures indeed show distinct signatures. The large-scale uniform model (characterised by an initially unlimited coherence scale) leads to correlations up to 90 degrees, while correlations for small-scale stochastic PMF models drop by factor of $100$ at $ 0.17, 0.13$ and 0.11 degrees angular scales, corresponding to $5.24, 4.03$ and $3.52$ Mpc scales (at $z=2$ redshift) for magnetic fields with comoving $3.49, 1.81, 1.00 $ Mpc/h coherence scales, respectively; the correlation amplitude of the PMF model with comoving $\sim 19$ Mpc/h coherence scale drops only by factor of $10$ at 1 degree (30.6 Mpc). These results suggests that improvements in the modelling of Galactic RM will be necessary to investigate the signature of large-scale correlated PMFs. A comparison of $\langle \mathrm{RM_{IGM}}\rangle$ redshift dependence obtained from our simulations with that from the LOFAR Two-metre Sky Survey shows agreement with our previous upper limits' estimates on the PMF strength derived from RM-rms analysis.
astro-ph.co
astro-ph
astro-ph
11-26 00:00
arXiv:2511.19554v1 Announce Type: new Abstract: Centaurs populate relatively short-lived and rapidly evolving orbits in the giant-planet region and are believed to be one of the solar system's most complex and diverse populations. Most Centaurs are linked to origins in the dynamically excited component of the trans-Neptunian region, and are often considered an intermediate phase in the evolution of Jupiter-family comets (JFCs). Additionally, the Centaur region hosts objects from varied source populations and having different dynamical histories. In this chapter, we focus on the physical processes responsible for the evolution of this heterogeneous population in the giant-planet region. The chapter begins with a brief review on the origin and early evolution that determine Centaurs' properties prior to entering the giant-planet region. Next, we discuss the thermal, collisional, and tidal processes believed to drive the changes Centaurs undergo. We provide a comprehensive review of the evidence for evolutionary changes derived from studies of the activity, physical properties, and surface characteristics of Centaurs and related populations, such as trans-Neptunian objects, JFCs, and Trojans. This chapter reveals a multitude of gaps in the current understanding of the evolution mechanisms acting in the giant-planet region. In light of these open questions, we conclude with an outlook on future telescope and spacecraft observations, detailing how they are expected to elucidate Centaur evolution processes.
astro-ph.ep
astro-ph
astro-ph
11-26 00:00
arXiv:2511.19587v1 Announce Type: new Abstract: Narrow-line Seyfert 1 galaxies (NLSy1s) are a subclass of active galactic nuclei (AGNs), commonly associated with rapidly accreting, relatively low-mass black holes ($10^6$ - $10^8 M_\odot$) hosted in spiral galaxies. Although typically considered to have high Eddington ratios, recent observations, particularly of $\gamma$-ray-emitting NLSy1s, have raised questions about their true black hole masses, with some estimates approaching those of Broad-line Seyfert 1 (BLSy1) systems. In this work, we present the recalibrated mass estimations for a large sample of NLSy1s galaxies with z $<0.8$. We apply the damped random walk (DRW) formalism to a comparison set of 1,141 NLSy1 and 1,143 BLSy1 galaxies, matched in redshift and bolometric luminosity using SDSS DR17 spectroscopy. Our analysis employs a multivariate calibration that incorporates both the Eddington ratio and the rest-frame wavelength to refine the mass estimates. We obtain median DRW-based black hole masses of $\text{log}(M_{\text{BH}}^{\text{DRW}}/M_\odot) = 6.25 \pm 0.65$ for NLSy1s and $7.07 \pm 0.67$ for BLSy1s, in agreement with their respective virial mass distributions. Furthermore, we identify strong inverse trends between the variability amplitude and both optical luminosity and FeII emission strength, consistent with a scenario where higher accretion rates suppress long-term optical variability. These findings reinforce the view that NLSy1s harbor smaller black holes and highlight the value of variability-based approaches in tracing AGN accretion properties.
astro-ph.ga
astro-ph
astro-ph
11-26 00:00
arXiv:2511.19591v1 Announce Type: new Abstract: We report on follow-up observations with XMM-Newton, the FORS2 instrument at the ESO-VLT, and FAST, aiming to characterise the nature of five thermally emitting isolated neutron star (INS) candidates recently discovered from searches in the footprint of the Spectrum Roentgen Gamma (SRG)/eROSITA All-sky Survey. We find that the X-ray spectra are predominantly thermal and can be described by low-absorbed blackbody models with effective temperatures ranging from 50 to 210 eV. In two sources, the spectra also show narrow absorption features at $300 - 400$ eV. Additional non-thermal emission components are not detected in any of the five candidates. The soft X-ray emission, the absence of optical counterparts in four sources, and the consequent large X-ray-to-optical flux ratios $>3000 - 5400$ confirm their INS nature. For the remaining source, eRASSU J144516.0-374428, the available data do not allow a confident exclusion of an active galactic nucleus nature. However, if the source is Galactic, the small inferred X-ray emitting region is reminiscent of a heated pulsar polar cap, possibly pointing to a binary pulsar nature. X-ray timing searches do not detect significant modulations in all candidates, implying pulsed fraction upper limits of 13 - 19% ($0.001-13.5$ Hz). The absence of pulsations in the FAST observations targeting eRASSU J081952.1-131930 and eRASSU J084046.2-115222 excludes periodic magnetospheric emission at 1 - 1.5 GHz with an $8\sigma$ significance down to 4.08 $\mu$Jy and 2.72 $\mu$Jy, respectively. The long-term X-ray emission of all sources does not imply significant variability. Additional observations are warranted to establish exact neutron star types. At the same time, the confirmation of the predominantly thermal neutron star nature in four additional sources highlights the power of SRG/eROSITA to complement the Galactic INS population.
astro-ph.he
astro-ph
astro-ph
11-26 00:00
arXiv:2511.19594v1 Announce Type: new Abstract: We introduce a novel framework for upsampled Point Spread Function (PSF) modeling using pixel-level Bayesian inference. Accurate PSF characterization is critical for precision measurements in many fields including: weak lensing, astrometry, and photometry. Our method defines the posterior distribution of the pixelized PSF model through the combination of an analytic Gaussian likelihood and a highly expressive generative diffusion model prior, trained on a library of HST ePSF templates. Compared to traditional methods (parametric Moffat, ePSF template-based, and regularized likelihood), we demonstrate that our PSF models achieve orders of magnitude higher likelihood and residuals consistent with noise, all while remaining visually realistic. Further, the method applies even for faint and heavily masked point sources, merely producing a broader posterior. By recovering a realistic, pixel-level posterior distribution, our technique enables the first meaningful propagation of detailed PSF morphological uncertainty in downstream analysis. An implementation of our posterior sampling procedure is available on GitHub.
astro-ph.im
astro-ph
astro-ph
11-26 00:00
arXiv:2511.19605v1 Announce Type: new Abstract: Fast $\gamma$-ray variability in blazars remains a central puzzle in high-energy astrophysics, challenging standard shock acceleration models. Blazars, a subclass of active galactic nuclei (AGN) with jets pointed close to our line of sight, offer a unique view into jet dynamics. Blazar $\gamma$-ray light curves exhibit rapid, high-amplitude flares that point to promising alternative dissipation mechanisms such as magnetic reconnection. This study uses three-dimensional relativistic magnetohydrodynamic (RMHD) and resistive relativistic magnetohydrodynamic (ResRMHD) simulations with the PLUTO code to explore magnetic reconnection in turbulent, magnetized plasma columns. Focusing on current-driven kink instabilities, we identify the formation of current sheets due to magnetic reconnection, leading to plasmoid formation. We develop a novel technique combining hierarchical structure analysis and reconnection diagnostics to identify reconnecting current sheets. A statistical analysis of their geometry and orientation reveals a smaller subset that aligns closely with the jet axis, consistent with the jet-in-jet model. These structures can generate relativistically moving plasmoids with significant Doppler boosting, offering a plausible mechanism for the fast flares superimposed on slowly varying blazar light curves. These findings provide new insights into the plasma dynamics of relativistic jets and strengthen the case for magnetic reconnection as a key mechanism in blazar $\gamma$-ray variability.
astro-ph.he
astro-ph
astro-ph
11-26 00:00
arXiv:2511.19607v1 Announce Type: new Abstract: Cosmological simulations predict significant secondary dependencies of halo clustering on internal properties and environment. Detecting these subtle signals in observational data remains challenging, with important ramifications for galaxy evolution and cosmology. We probe secondary halo bias in observational survey data, using galaxy groups as dark matter halo proxies. We quantify secondary bias using central galaxy colour and environmental diagnostics. We use an extended, refined galaxy group catalogue from the Sloan Digital Sky Survey. Secondary bias is defined as any deviation in group clustering strength at fixed mass, quantified through the projected two-point correlation function. Our environmental analysis uses DisPerSE to compute distances to critical points of the density field, incorporating local group overdensity measurements on multiple scales. We robustly detect several forms of secondary bias in the clustering of galaxy groups. At fixed mass, groups hosting red central galaxies are more strongly clustered than those with blue centrals, with $b_{\rm relative}$ ranging from $\sim 1.2$ for the 15\% reddest centrals to $\sim 0.8$ for the bluest ones. Environmental dependencies based on cosmic-web distances are also present, though significantly weaker and largely mass-independent. The strongest signal arises from local overdensity: groups in the densest 15\% of environments reach $b_{\rm relative} \sim 1.4$, while those in the least dense regions fall to $b_{\rm relative} \sim 0.7$. These results establish a clear observational hierarchy for secondary halo bias. The colour of central galaxies correlates with the local group overdensity, which, in turn, correlates with the bias at fixed group mass. Assuming that central galaxy colour traces halo assembly history, this three-stage picture offers a conceptual link between our results and halo assembly bias.
astro-ph.co
astro-ph
astro-ph
11-26 00:00
arXiv:2511.19608v1 Announce Type: new Abstract: We present the mass-metallicity relation for star-forming galaxies in the MUSE Quasar Nebula 01 (MQN01) field, a massive cosmic web node at $z \sim 3.245$, hosting one of the largest overdensities of galaxies and AGNs found so far at $z > 3$. Through James Webb Space Telescope (JWST) Near Infrared Spectrograph (NIRSpec) spectra and images from JWST and Hubble Space Telescope (HST), we identify a sample of 9 star-forming galaxies in the MQN01 field with detection of nebular emission lines ($\rm H\beta$, [OIII], $\rm H\alpha$, [NII]), covering the mass range of $\rm 10^{7.5}M_\odot - 10^{10.5}M_\odot$. We present the relations of the emission-line flux ratios versus stellar mass for the sample and derive the gas-phase metallicity based on the strong line diagnostics of [OIII]$\lambda5008$/$\rm H\beta$ and [NII]$\lambda6585$/$\rm H\alpha$. Compared to the typical, field galaxies at similar redshifts, MQN01 galaxies show relatively higher [NII]$\lambda6585$/$\rm H\alpha$ and lower [OIII]$\lambda5008$/$\rm H\beta$ at the same stellar mass, which implies a higher metallicity by about $0.25\pm 0.07$ dex with respect to the field mass-metallicity relation. These differences are decreased considering the ``Fundamental Metallicity Relation'', i.e. if the galaxies' Star Formation Rates (SFR) are also taken into account. We argue that these results are consistent with a scenario in which galaxies in overdense regions assemble their stellar mass more efficiently (or, equivalently, start forming at earlier epochs) compared to field galaxies at similar redshifts.
astro-ph.ga
astro-ph
astro-ph
11-26 00:00
arXiv:2511.19609v1 Announce Type: new Abstract: JWST has revealed an abundance of low-luminosity active galactic nuclei (AGN) at high redshifts ($z > 3$), pushing the limits of black hole (BH) science in the early Universe. Results have claimed that these BHs are significantly more massive than expected from the BH mass-host galaxy stellar mass relation derived from the local Universe. We present a comprehensive census of the BH populations in the early Universe through a detailed stacking analysis of galaxy populations, binned by luminosity and redshift, using JWST spectroscopy from the CEERS, JADES, RUBIES, and GLASS extragalactic deep field surveys. Broad H$\alpha$ detections in $31\%$ of the stacked spectra (5/16 bins) imply median BH masses of $10^{5.21} - 10^{6.13}~ \rm{M_{\odot}}$ and the stacked SEDs of these bins indicate median stellar masses of $10^{7.84} - 10^{8.56} ~\rm{M_{\odot}}$. This suggests that the median galaxy hosts a BH that is at most a factor of 10 times over-massive compared to its host galaxy and lies closer to the locally derived $M_{BH}-M_*$ relation. We investigate the seeding properties of the inferred BHs and find that they can be well-explained by a light stellar remnant seed undergoing moderate Eddington accretion. Our results indicate that individual detections of AGN are more likely to sample the upper envelope of the $M_{BH}-M_*$ distribution, while stacking on ``normal" galaxies and searching for AGN signatures can overcome the selection bias of individual detections.
astro-ph.ga
astro-ph
astro-ph
11-26 00:00
arXiv:2511.19630v1 Announce Type: new Abstract: Supernova (SN) feedback-driven galactic outflows are a key physical process that contributes to the baryon cycle by regulating the star formation activity, reducing the amount of metals in low-mass galaxies and enriching the circumgalactic (CGM) and intergalactic media (IGM). We aim to understand the chemical loop of sub-Milky Way (MW) galaxies and their nearby regions. We studied 15 simulated central sub-MW galaxies (M* <= 10^10 Msun) and intermediate-mass galaxies (M* \sim 10^10 Msun) from the CIELO-P7 high-resolution simulations. We followed the evolution of the progenitor galaxies, their properties and the characteristics of the outflows within the redshift range z = [0, 7]. We used two dynamically-motivated outflow definitions, unbound outflows and expelled mass rates, to quantify the impact of SN feedback. At z \sim 0, sub-MW galaxies have a larger fraction of their current oxygen mass in the gas phase but have expelled a greater portion beyond the virial radius, compared to their higher-mass counterparts. Galaxies with M* <\sim 10^9 Msun have 10-40 per cent of their total oxygen mass within R200 in the CGM, and an equivalent to 10-60 per cent expelled into the IGM. In contrast, more massive galaxies have most of the oxygen mass locked by the stellar populations. The CGM of low-mass galaxies predominantly contains oxygen low-temperature gas, acting as a metal reservoir. We find that the outflows are more oxygen-rich for sub-MW galaxies, Zout/ZISM \sim 1.5, than for higher-mass galaxies, Zout/ZISM <= 0.5, particularly for z < 2. Mass-loading factors of eta_out \sim 0 - 6 are detected in agreement with observations (abridged).
astro-ph.ga
astro-ph
astro-ph
11-26 00:00
arXiv:2511.19632v1 Announce Type: new Abstract: We present a detailed analysis of the vertical and radial structure of mono-age stellar populations in three edge-on lenticular galaxies (FCC 153, FCC 170, and FCC 177) in the Fornax cluster, using deep MUSE observations. By measuring the half-mass radius (R$_{50}$) and half-mass height (z$_{50}$) across 1 Gyr-wide age bins, we trace the spatial evolution of stellar populations over cosmic time. All galaxies exhibit a remarkably constant disc thickness for all stars younger than ~6 Gyr, suggesting minimal secular heating and limited impact from environmental processes such as tidal shocking or harassment. Evidence of past mergers (8-10 Gyr ago) is found in the increase of z$_{50}$ for older populations. We find that accreted (metal-poor) stars have been deposited in quite thick configurations, but that the interactions only moderately thickened pre-existing stars in the galaxies, and only caused mild flaring in the outer regions of the discs. The radial structure of the discs varies across galaxies, but in all cases we find that the radial extent of mono-age populations remains constant or grows over the past 8 Gyr. This leads us to argue that within the radial range we consider, strangulation, rather than ram-pressure stripping, is the dominant quenching mechanism in those galaxies. Our results highlight the usefulness of analysing the structure of mono-age population to uncover the mechanisms driving galaxy evolution, and we anticipate broader insights from the GECKOS survey, studying 36 nearby edge-on disc galaxies.
astro-ph.ga