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Physics Astrophysics

astro-ph Watch Astrophysics

Saturday 20 June

High Energy Astrophysical Phenomena

A grid of fast-rotating, chemically-homogeneous, supernova and/or long-GRB progenitors

M. Renzo, O. Gottlieb, H. S. Chan et al. (+6 more)

The understanding of the mechanism(s) by which massive stars collapse and possibly explode is rapidly maturing. Uncertainties in the structure of the stellar core at the onset of collapse are often dominant in numerical simulations, and a limited number of progenitor grids are available. This is especially true for explosions where rotation and magnetic fields play a significant or primary role. We present a grid of 113 single-star models with initial masses $M_{\rm ZAMS}=30-90\,M_{\odot}$ and initial rigid rotation $\omega_{\rm ZAMS}=0.5-0.99\,\omega_{\rm crit}$ computed at $Z=0.001$ with the open-source stellar evolution code MESA. We adopt a 128-isotope nuclear reaction network capable of following the weak reactions deleptonizing the core during and after silicon core burning. By construction, these models experience rotationally-induced chemically-homogeneous evolution, and reach the onset of collapse ($v_{\rm infall}\lesssim -300\,\mathrm{km\ s^{-1}}$) with large and structured amounts of angular momentum, possibly sufficient to form accretion disks on a proto-compact object. Therefore, these progenitor structures provide a homogeneous set of models with updated input physics and improved algorithmic accuracy to understand stellar explosions of (some types of) stripped-envelope supernovae, possibly jetted and/or broad-lined, collapsars or magnetar-powered, and/or long $\gamma$-ray bursts.
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All authors M. Renzo, O. Gottlieb, H. S. Chan, J. A. Goldberg, A. Grichener, K. Sen, N. Shah, E. Farag, Matteo Cantiello

Solar and Stellar Astrophysics

On the stellar parameter dependence of the combined Fe I and Fe II chromospheric emission-line in the wings of the Ca II K line

Faiber Rosas-Portilla, Luis Zapata, Klaus-Peter Schröder et al. (+3 more)

We present an analysis of the chromospheric emission of Fe I + Fe II in the wing of the Ca II K line of 21 G and K giant stars. Stellar parameters and absolute chromospheric fluxes were obtained by comparison with PHOENIX models. The iron-blend emission shows a proportionality with the Ca II K flux for stars with similar stellar parameters and also for individual stars observed at different epochs, confirming that both diagnostics seems to respond to the same underlying chromospheric conditions. We found a dependence of the iron-blend emission on stellar parameters by fitting a power-law relation. The exponent of the effective temperature statistically matches with that found for Ca II K; which, together with a metallicity dependence, indicate that the iron-blend may act as an indirect tracer of chromospheric thermal conditions. The chromospheric emission flux ratio (Fe I + Fe II)/Ca II K exhibits a distinct slope change around log g approx. 2.5 dex; which causes the gravity dependence to be different for stars with gravities lower and higher than 2.5 dex. This behavior suggests a transition between regimes where the two diagnostics probe similar physical conditions and where they begin to diverge in the sensitivity to the chromospheric extension. We discuss the implications of this behavior for the thermal structure of the lower chromosphere and for the formation heights of both diagnostics.
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All authors Faiber Rosas-Portilla, Luis Zapata, Klaus-Peter Schröder, Sandra González-Enríquez, Dennis Jack, Robert Stencel

Friday 19 June

Cosmology and Nongalactic Astrophysics · Cross-listed from gr-qc

Black bounce solutions in a realistic dark matter halo from M60*

Ednaldo L. B. Junior, José Tarciso S. S. Junior, Francisco S. N. Lobo et al. (+5 more)

We formulate a Simpson-Visser black bounce solution embedded in a dark matter halo. The latter is modeled using an empirical density profile calibrated from observations of the elliptical galaxy NGC 4649 (M60), based on imaging from the Hubble Space Telescope, stellar velocity dispersion data, and the dynamics of globular clusters. The resulting spacetime metric, in addition to retaining dependence on the mass parameter $m$, the asymptotic circular velocity $V_c$, and the halo scale radius $a$, also depends on the regularization parameter $q_H$. It reduces to the canonical black bounce solution without a halo in the limit $V_c\to0$ (or $a\to\infty$), and to the Schwarzschild solution with a dark matter halo when $q_H\to0$. We analyze the response of fundamental geometrical and physical quantities in the presence of a halo, such as the event horizon radius, the shadow size, and some curvature invariants. In particular, we show the observational range of the shadow radius, from the imaging of Sagittarius A*, constrains the parameter space of the solution to regular black hole configurations, excluding wormhole scenarios. We study the dynamics of massless particles here through the effective potential and examine thermodynamic properties, highlighting the impact on thermodynamic potentials in terms of entropy. Finally, we extend the analysis to scenarios with electromagnetic fields non-minimally coupled to a phantom scalar field, considering configurations with either purely magnetic or purely electric charge. Our results suggest that the dark matter halo influences both the internal geometry and the observational properties of black bounces, imposing constraints on the solution's parameter space from astrophysical data. This highlights the need to include astrophysical environments in modeling regular black holes and wormholes, offering new tests of gravity in the strong-field regime.
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All authors Ednaldo L. B. Junior, José Tarciso S. S. Junior, Francisco S. N. Lobo, Jorde A. A. Ramos, Manuel E. Rodrigues, Diego Rubiera-Garcia, Luís F. Dias da Silva, Henrique A. Vieira

Astrophysics of Galaxies

Euclid Quick Data Release (Q1): The geometry of dark matter halos from extragalactic streams

Euclid Collaboration: N. Starkman, J. Nibauer, S. Pearson et al. (+294 more)

Wide-field surveys like Euclid mark a new era of extragalactic stellar stream studies. With a large number of streams, it is now possible to constrain the dark matter halos of galaxies in a cosmological volume and draw comparisons to theoretical expectations for the geometry of dark matter halos. This study combines Euclid imaging with visual detection and segmentation annotations to analyse streams. We use projected stream morphologies to constrain the shape and centre-of-mass position (CoM) of each host galaxy's potential, jointly probing baryonic and dark matter distributions. These inferences complement weak lensing methods, with sensitivity to halo profile and geometry on sub-virial scales. The method enables both stacked, population-level constraints on halo flattening and CoM position, and constraints on these quantities for individual halos. We also present a novel method for transforming segmentation maps of stellar streams into smooth, curvature-preserving tracks optimised for fast and robust dynamical inference. This approach enables rapid modelling of stream morphology, supports a statistically rigorous combination of constraints across multiple streams within a single galaxy, and enables joint inference across galactic hosts. From our study of 13 galaxies with prominent tidal streams, we find agreement with spherical halos, albeit a mild preference for flattening with $q = 0.95^{+0.05}_{-0.10}$ at 68% confidence. This is promising early agreement with $\Lambda$CDM predictions. With thousands more discovered streams expected across \Euclid's mission, our programme will enable precise measurements of halo shapes and CoM positions across large samples and redshifts, offering constraints on the geometry of dark matter halos.
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All authors Euclid Collaboration: N. Starkman, J. Nibauer, S. Pearson, S. Wu, M. Walmsley, L. Necib, J. Bovy, F. R. Marleau, E. Sola, D. Scott, B. Altieri, S. Andreon, N. Auricchio, C. Baccigalupi, M. Baldi, A. Balestra, S. Bardelli, P. Battaglia, A. Biviano, M. Bolzonella, E. Branchini, M. Brescia, J. Brinchmann, S. Camera, V. Capobianco, C. Carbone, J. Carretero, S. Casas, M. Castellano, G. Castignani, S. Cavuoti, K. C. Chambers, A. Cimatti, C. Colodro-Conde, G. Congedo, C. J. Conselice, L. Conversi, Y. Copin, A. Costille, F. Courbin, H. M. Courtois, M. Cropper, H. Degaudenzi, G. De Lucia, H. Dole, F. Dubath, C. A. J. Duncan, X. Dupac, S. Dusini, S. Escoffier, M. Fabricius, M. Farina, R. Farinelli, S. Ferriol, F. Finelli, P. Fosalba, S. Fotopoulou, M. Frailis, E. Franceschi, M. Fumana, L. Gabarra, S. Galeotta, K. George, B. Gillis, C. Giocoli, P. Gómez-Alvarez, J. Gracia-Carpio, A. Grazian, F. Grupp, S. V. H. Haugan, W. Holmes, F. Hormuth, A. Hornstrup, M. Huertas-Company, K. Jahnke, M. Jhabvala, B. Joachimi, S. Kermiche, A. Kiessling, B. Kubik, M. Kümmel, M. Kunz, H. Kurki-Suonio, A. M. C. Le Brun, S. Ligori, P. B. Lilje, V. Lindholm, I. Lloro, M. Magliocchetti, G. Mainetti, O. Mansutti, O. Marggraf, M. Martinelli, N. Martinet, F. Marulli, R. J. Massey, N. Mauri, E. Medinaceli, S. Mei, M. Melchior, M. Meneghetti, E. Merlin, G. Meylan, P. Monaco, A. Mora, M. Moresco, C. Moretti, L. Moscardini, R. Nakajima, C. Neissner, R. C. Nichol, S.-M. Niemi, J. W. Nightingale, C. Padilla, S. Paltani, F. Pasian, K. Pedersen, W. J. Percival, V. Pettorino, A. Pezzotta, S. Pires, G. Polenta, M. Poncet, L. A. Popa, L. Pozzetti, F. Raison, A. Renzi, J. Rhodes, G. Riccio, I. Risso, E. Romelli, M. Roncarelli, C. Rosset, R. Saglia, Z. Sakr, D. Sapone, B. Sartoris, P. Schneider, A. Secroun, E. Sihvola, P. Simon, C. Sirignano, G. Sirri, L. Stanco, P. Tallada-Crespí, A. N. Taylor, I. Tereno, N. Tessore, S. Toft, R. Toledo-Moreo, F. Torradeflot, A. Tsyganov, I. Tutusaus, E. A. Valentijn, J. Valiviita, T. Vassallo, G. Verdoes Kleijn, A. Veropalumbo, Y. Wang, J. Weller, A. Zacchei, G. Zamorani, F. M. Zerbi, E. Zucca, M. Ballardini, E. Bozzo, C. Burigana, R. Cabanac, M. Calabrese, A. Cappi, T. Castro, J. A. Escartin Vigo, J. García-Bellido, J. Macias-Perez, R. Maoli, J. Martín-Fleitas, R. B. Metcalf, M. Pöntinen, V. Scottez, M. Sereno, M. Tenti, M. Tucci, M. Viel, M. Wiesmann, Y. Akrami, I. T. Andika, G. Angora, S. Anselmi, M. Archidiacono, F. Atrio-Barandela, L. Bazzanini, D. Bertacca, M. Bethermin, F. Beutler, A. Blanchard, L. Blot, M. L. Brown, S. Bruton, A. Calabro, B. Camacho Quevedo, F. Caro, C. S. Carvalho, F. Cogato, A. R. Cooray, O. Cucciati, F. De Paolis, G. Desprez, A. Díaz-Sánchez, S. Di Domizio, J. M. Diego, P.-A. Duc, V. Duret, M. Y. Elkhashab, A. Enia, Y. Fang, A. Finoguenov, A. Franco, K. Ganga, T. Gasparetto, R. Gavazzi, E. Gaztanaga, F. Giacomini, F. Gianotti, E. J. Gonzalez, G. Gozaliasl, A. Gruppuso, M. Guidi, C. M. Gutierrez, A. Hall, C. Hernández-Monteagudo, H. Hildebrandt, J. Hjorth, L. K. Hunt, J. J. E. Kajava, Y. Kang, V. Kansal, D. Karagiannis, K. Kiiveri, J. Kim, C. C. Kirkpatrick, S. Kruk, M. Lattanzi, M. Lembo, F. Lepori, G. Leroy, J. Lesgourgues, T. I. Liaudat, S. J. Liu, A. Loureiro, G. Maggio, A. Manjón-García, F. Mannucci, C. J. A. P. Martins, L. Maurin, M. Miluzio, G. Morgante, S. Nadathur, K. Naidoo, A. Navarro-Alsina, S. Nesseris, D. Paoletti, F. Passalacqua, K. Paterson, L. Patrizii, C. Pattison, A. Pisani, D. Potter, G. W. Pratt, S. Quai, M. Radovich, K. Rojas, W. Roster, S. Sacquegna, M. Sahlén, D. B. Sanders, E. Sarpa, A. Schneider, D. Sciotti, E. Sellentin, F. Shankar, J. Stadel, K. Tanidis, F. Tarsitano, G. Testera, R. Teyssier, S. Tosi, A. Troja, M. Urbano, C. Valieri, A. Venhola, D. Vergani, G. Verza, P. Vielzeuf, S. Vinciguerra, N. A. Walton, J. R. Weaver, A. H. Wright

Earth and Planetary Astrophysics

Radiatively Controlled Thermal Stability of High-Altitude Clouds in Exoplanetary Atmospheres

Taro M. Shefferson-Nagata and Kazumasa Ohno

One of the most striking findings of exoplanetary science is the ubiquity of clouds. A conventional approach to infer the cloud compositions is to utilize the thermochemical equilibrium model assuming the same temperature shared with clouds and ambient gases; however, this assumption is actually not always valid, especially in the tenuous upper atmospheres where particle-gas collisions are infrequent. In this study, we investigate the radiative equilibrium temperatures of exoplanetary clouds to assess the thermal stability of aerosols in the low atmospheric pressure limit. For eight cloud-forming condensates (KCl, ZnS, Na$_2$S, MnS, SiO$_2$, Mg$_2$SiO$_4$, Fe, and Al$_2$O$_3$), we solve the energy balance between stellar radiative heating and infrared cooling to calculate the particle temperature, which is then compared with their condensation temperatures. We find three composition-dependent groups in the particle-temperature behavior, and show that silicate condensates (SiO$_2$ and Mg$_2$SiO$_4$) maintain a cool enough temperature in a wide range of stellar and planetary conditions. Conversely, sulfide condensates (ZnS, Na$_2$S, and MnS) are readily heated to their sublimation temperatures even on temperate planets. WASP-17b and HD 189733b fall within the thermodynamically stable regime for SiO$_2$ clouds, consistent with recent JWST observations. We also examine the vertical profiles of cloud temperatures on WASP-17b, showing that Fe clouds cannot exist on the dayside, and Al$_2$O$_3$ clouds can exist only in a confined region, even though atmospheric temperature appears to allow the formation of these clouds. This study provides novel insights on cloud compositions in upper exoplanetary atmospheres, testable by upcoming atmospheric surveys of JWST and Ariel.
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Instrumentation and Methods for Astrophysics · Cross-listed from cs.RO

RoverDevKit: An open, physics-grounded tradespace toolkit for conceptual design of lunar micro-rovers

Jon Reifschneider

Lunar micro-rovers under 50 kg are a rapidly growing vehicle class, yet open, benchmarked tools for running optimization across design trades remain scarce. Rover sizing is a highly coupled problem with a feedback loop specific to surface vehicles: a heavier rover sinks deeper into loose regolith, deeper sinkage costs more power, more power requires a larger array, and the array adds mass. We present RoverDevKit, a tradespace exploration toolkit with an open evaluator that couples a closed-form wheel-soil model with bottom-up mass, solar-power, thermal-survival, and traverse models. It is fast enough to serve as the fitness function of a multi-objective genetic algorithm (NSGA-II): one search of 3000 mission evaluations takes under a minute on a single laptop core. We use it to map the trades among distance traveled, vehicle mass, and slope capability on mare, polar, highland, and crater-rim missions. Across those missions the limiting factor changes: energy storage at high latitude, slope traction on loose highland regolith, and traverse range on mare and crater-rim terrain. The wheel-soil model matches measured single-wheel drawbar pull on two independent datasets to within the 20-30% error typically reported for this class of model, and the mass model predicts published 5-50 kg rover masses to 10.5% median absolute error. A check against five published in-class designs places them near the designs the optimizer selects. Re-running the search after applying that wheel-soil comparison error leaves these conclusions unchanged.
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Astrophysics of Galaxies

Reaction Mechanisms and Kinetics of CN and CCH with H2CS: Implications for Interstellar Sulfur Chemistry

Boutheïna Kerkeni, Ghofrane Ouerfelli, Nicole Feautrier et al. (+1 more)

We report an ab initio and master-equation investigation of the gas-phase reactions of thioformaldehyde (H2CS) with CN and CCH radicals, motivated by the recent detection of the S-containing species HCSCN and HCSCCH in cold interstellar environments. Structures and frequencies were obtained at the DSD-PBEP86/aug-cc-pVTZ level, with energetics refined by CCSD(T)-F12a calculations and kinetics treated using an energy-grained master equation. The CN + H2CS reaction proceeds through orientation-dependent entrance channels. Two barrierless addition pathways lead to a connected multi-well network that preferentially forms cyano thioformaldehyde, HCSCN + H, whereas abstraction-type channels leading to HNC + HCS or HCN + HCS contribute only marginally. The calculated kinetics indicate capture-controlled low-temperature reactivity and a strong preference for HCSCN formation, suggesting that this reaction should be considered in astrochemical models of cold clouds. For CCH + H2CS, barrierless capture gives access to two connected entrance adducts. Although the cyclic product is the most exothermic channel, its formation is kinetically hindered by a high-lying late transition state. The flux is shared between propynethial formation, HCSCCH + H, and the HCCH + HCS channel, with the latter being favored. These results show that subtle differences in radical structure, bonding preferences, and entrance-channel topology strongly affect product branching in S-containing radical-molecule reactions. The computed mechanisms and rate coefficients provide useful input for astrochemical models of sulfur chemistry in cold molecular clouds and for interpreting recent molecular detections in sources such as TMC-1.
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All authors Boutheïna Kerkeni, Ghofrane Ouerfelli, Nicole Feautrier, Christian Balança

Astrophysics of Galaxies

A new solution for the mass growth of Black Holes consistent with thermodynamics

María F. La Rotta Wilches and Roger Coziol

The James Webb Space Telescope (JWST) has recently revealed evidence of supermassive black holes (SMBHs) forming in the cores of high redshift galaxies that grew in mass extremely rapidly during the first billion years of the universe. In this study we present a new solution where the growth mass factor of BHs, $\gamma(t) \propto \dot M_{BH}/M_{BH}$, varies with time, following the changes of radiative efficiency, $\epsilon$, and Eddington ratio, $\lambda_{Edd}$, caused by the variation in accretion flow. By optimizing the accretion rate, $\dot M_{BH}$, we obtained a solution that is universal, that is, which applies to any BH at any redshift. This suggests that the mass of the BH is a thermodynamics state function, in good agreement with the no hair theorem and the four laws of mechanics of BHs.
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Instrumentation and Methods for Astrophysics

Digital Beam Pattern Optimisation for the GRAO 32-m Telescope: A Comparative Analysis of FIR Filter Design Methods

Theophilus Ansah-Narh, Nia Imara, Benedicta Woode et al. (+1 more)

The scientific utility of large single-dish radio telescopes depends critically on the stability and fidelity of their beam patterns, which govern angular resolution, sensitivity, and polarimetric accuracy. For the 32-m Ghana Radio Astronomy Observatory (GRAO) antenna, electromagnetic simulations reveal residual sidelobes, structural diffraction, and cross-polar leakage that limit performance in high-dynamic-range and polarisation-sensitive observations. To address these limitations, we develop a finite-impulse-response (FIR) spatial filtering framework that reformulates beam optimisation as a digital signal processing problem. By exploiting the equivalence between angular displacement and spatial frequency, classical FIR design methods, window-based and Parks-McClellan algorithms are adapted to operate directly on simulated Jones fields. This approach enables controlled suppression of high spatial frequency artefacts responsible for sidelobes and polarisation mixing, while preserving the telescope's diffraction-limited resolution. Applied to the GRAO 5 GHz beam model, the method achieves substantial reductions in near-in sidelobe ripple, improves beam smoothness, and lowers cross-polar leakage below -30 dB at boresight. These improvements translate into enhanced calibration stability and polarimetric precision, strengthening the telescope's capacity for Very Long Baseline Interferometry, spectral-line surveys, and pulsar timing. Beyond GRAO, the method provides a generalisable, non-invasive, and computationally efficient pathway for beam control applicable to other single-dish and phased-array instruments. The results establish digital spatial filtering as a practical complement to conventional optical or mechanical optimisation, advancing the integration of electromagnetic modelling and signal processing in next-generation radio astronomical instrumentation.
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All authors Theophilus Ansah-Narh, Nia Imara, Benedicta Woode, Emmanuel Proven Adzri

Earth and Planetary Astrophysics

ARCO-Mars: A Unified Cloud-Optimized Archive of Mars Atmosphere Reanalysis

Ananyo Bhattacharya

Long-term records of the Martian atmosphere based on general circulation models and reanalysis of atmospheric state variables are important to understand the diurnal, seasonal, and climatological changes of the planet. Atmospheric dynamics of the Martian atmosphere are strongly influenced by the characterization of dust lifting, solar insolation, and spatial variations in topography. We present ARCO-Mars, a unified Analysis-Ready Cloud-Optimized dataset providing integrated access to three independent Mars atmospheric reanalysis products: EMARS, MACDA, and OpenMARS spanning over Mars Years 24-35. These reanalyses assimilate thermal infrared retrievals from the MGS/TES, ODY/THEMIS, and MRO/MCS instruments, providing both two and three-dimensional surface and atmospheric state variables, including temperature, winds, surface pressure, and dust optical depth. The dataset is stored in Zarr v3 format and hosted on HuggingFace, enabling efficient cloud-based access without requiring local storage of the full archive. We compare the state variables between the three reanalysis products to identify systematic differences, attributed to differences in data assimilation and general circulation models. ARCO-Mars provides a community resource for Mars atmospheric science, numerical weather prediction validation, and machine learning applications, including weather forecasting and data assimilation.
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High Energy Astrophysical Phenomena

Getting Tilted: Random Walk of Binary Black Hole Spin-Orbit Alignment in Dense Star Clusters

Maia A. S. Martinez, Christopher E. O'Connor, Fulya K{\i}roğlu et al. (+1 more)

It is commonly assumed that the spin-orbit angles of binary black holes (BBHs) originating from dense stellar environments rapidly converge to an isotropic distribution following a number of strong gravitational encounters. We challenge this assumption by modeling the evolution of the BBH orbital angular momentum orientation through successive binary–single encounters as a random walk on the unit sphere, yielding an exact solution for the orientation distribution after $n$ encounters and a closed-form expression for the number of encounters required to reach isotropy. To characterize the step distribution, we conduct a large suite of Newtonian point-particle scattering experiments with an equal-mass binary, varying the mass of the single, and obtain semi-analytic expressions for both the mean step size and the full distribution of steps. Applying these results to BBHs with initially aligned spins, as may arise from the evolution of primordial massive binaries, we find that spin-orbit alignment can survive several strong encounters before being erased. This has direct implications for the slight trend toward spin-orbit alignment reported in GWTC-5.0 as well as for the retention of hierarchical merger products, such as the components of GW231123.
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All authors Maia A. S. Martinez, Christopher E. O'Connor, Fulya K{\i}roğlu, Frederic A. Rasio

High Energy Astrophysical Phenomena

Subgrid Modelling for Relativistic Magnetohydrodynamics with Machine Learning

William Cook and Sebastiano Bernuzzi

Resolving the impact of magnetic field instabilities in triggering small scale turbulent flow and the associated rearrangement of the field is of critical importance in understanding multimessenger observables in binary neutron star mergers, and angular momentum transport in neutron stars and accretion disks. Direct simulation of these instabilities are unfeasible, however large-eddy simulations can incorporate the impact of this turbulence with a subgrid model. We present the first machine-learning-based subgrid model for special relativistic magnetohydrodynamics, trained using a neural network. We demonstrate its performance in online simulations of the 3D Kelvin-Helmholtz instability through both a priori and a posteriori tests. Evaluated in a low resolution simulation, our model captures magnetic field amplification of a simulation at 4 times the resolution with a speed-up of a factor 44. This demonstrates the applicability of such methods in general relativistic simulations of neutron star mergers and other scenarios.
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Instrumentation and Methods for Astrophysics · Cross-listed from hep-ex

Towards LLM-Powered Automation of a Dark Matter Constraint Repository

Lanqing Yuan and Karthik Ramanathan

Dark matter constraint repositories are critical community infrastructure, yet the most widely-used are volunteer-maintained, a sustainability risk as results accelerate. Limits are typically published as figures rather than machine-readable records, compounding the burden. We present a large language model (LLM) pipeline that monitors arXiv, extracts limit curves, integrates them as code, and opens pull requests for human review. On a 329-paper benchmark of measured limits graded against the upstream-curated repository, it identifies the coupling type for 98.1% of gradable papers. The 81% yielding a comparable extraction reach a median residual of 0.17 dex from a single model read, and 51% of all papers land within a factor of two of the curator's curve. The LLM is confined to perception; arithmetic, unit conversion, and the guards that reject mis-extractions are deterministic, testable code. Deployed, the pipeline has generated limit proposals, but none have merged: governance of AI-generated scientific data is itself unsolved.
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Astrophysics of Galaxies

The $M$-$\sigma$ Relation Has to Break

Omri Nitzan and Re'em Sari

We revisit the growth of central black holes via tidal disruption events (TDEs) and plunges of stellar-mass black holes (sBHs). Our model incorporates the current understanding of mass segregation, where sBHs sink to the center, enhancing the rates of both TDEs and plunges. We demonstrate that in dense cluster cores, with densities exceeding $10^6\,\mathrm{M_\odot\,{pc}^{-3}}$, seeds of initial mass $M_0\gtrsim100\,M_\odot$ undergo runaway growth. This runaway terminates once the black hole radius of influence surpasses the core radius, or equivalently, most of the core mass has been consumed. This typically results in an intermediate-mass black hole (IMBH), within a few $\mathrm{Gyr}$. Subsequent growth proceeds as a power law. In contrast to observed supermassive black holes (SMBHs), which tightly follow the famous $M \propto \sigma^\beta$ with $\beta \cong5$, our derived sBH accretion rates, integrated over a galactic lifetime, predict final masses of $M\approx10^5\,M_\odot \times(\sigma/50\mathrm{km\;s^{-1}})^{2.5}$. While our prediction for the contribution of plunges to the growth of the IMBH is robust, the TDE contribution can be negligible if only a small fraction of their mass is actually accreted or up to 3 times higher than the plunges contribution if half a stellar mass gets accreted in each event. Below $M\sim10^5\,M_{\odot}$ this accreted star and sBH mass exceeds the extrapolation of the observed $M$-$\sigma$ relation. This predicts that the $M$-$\sigma$ scaling must flatten below $M \sim 10^5\,M_{\odot}$ to a shallower, $2.26<\beta<2.5$ profile. If confirmed by observations, this would indicate capture-driven growth.
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Cosmology and Nongalactic Astrophysics · Cross-listed from hep-ph

Globally Charged Vacuum Decay

Giulio Barni and Jose R. Espinosa

Vacuum decay at zero temperature is generically described by a real $O(4)$-symmetric Coleman bounce. When the scalar field driving the decay carries a conserved global charge, this picture changes qualitatively: the path integral must be projected onto a definite charge sector, the Euclidean field obeys twisted boundary conditions, and the saddle is complex. For the simplest case of a $U(1)$ global symmetry, we first reformulate this problem in a two-field real Euclidean description with a real saddle. We then solve the resulting two-dimensional partial differential equation problem describing the decay of a homogeneous charged medium to a deeper vacuum via bubble nucleation. At finite charge the bounce departs from $O(4)$ symmetry, the barrier between vacua is lowered, and the decay rate increases. Continuing the solution to real time, we find that charge rearrangement around the expanding wall costs phase-gradient energy and drives the bubble to a subluminal terminal velocity even in vacuum. We also clarify how the fixed-charge construction interfaces with finite-temperature and finite-chemical-potential descriptions.
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Astrophysics of Galaxies

Resolved Ages and Stellar Metallicities in Progenitors of Milky Way Analogs: A Closer Look at their Star Formation Histories since $z=5$

Vivian Yun Yan Tan, Adam Muzzin, Naadiyah Jagga et al. (+12 more)

We present the evolution of the resolved mass-weighted age, stellar metallicity, and sSFR of 872 Milky Way Analog (MWA) progenitors up to redshift $z=5$ from the Canadian Unbiased Cluster Survey (CANUCS). The metallicity and mass-weighted ages were obtained via spatially resolved SED-fitting with the non-parametric code Dense Basis. We split the sample into mergers versus non-mergers using the merger parameter from the Gini-$M_{20}$ plane obtained through Gini-$M_{20}$ analysis of the morphology of the stellar mass maps with Statmorph. Across our redshift range, non-mergers have negative or flat average age gradients from $-0.022$ to 0.005 dex/kpc, and positive or flat sSFR gradients from $-0.089$ to 0.092 dex/kpc, consistent with inside-out assembly. The average $\log(Z/\Zsun)$ gradients for non-mergers range from $-0.029$ to 0.044 dex/kpc, however, positive gradients only appear between $2 < z < 3$. At every redshift epoch, mergers typically have flatter age gradients, more negative sSFR gradients, and similar metallicity gradients compared to non-mergers. We divide the property maps of ongoing mergers into separate regions based on their component galaxies, and find little to no difference between the components' average ages or metallicities, but the less massive of the merging system is on average $0.1-0.4$ dex higher in sSFR. Our results point to major mergers contributing some momentary disruption to the general trend of inside-out mass assembly, but does not upend the overall picture of MWA disks growing inside-out over cosmic time.
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All authors Vivian Yun Yan Tan, Adam Muzzin, Naadiyah Jagga, Visal Sok, Ghassan T. E. Sarrouh, Gregor Rihtaršič, Roberto Abraham, Yoshihisa Asada, Maruša Bradač, Kartheik Iyer, Nicholas S. Martis, Gaël Noirot, Marcin Sawicki, Chris J. Willott, Sunna Withers

Earth and Planetary Astrophysics

The GAPS Programme at TNG LXXIV. A reanalysis of the planetary systems TOI-1272 and TOI-1694 with HARPS-N and retraction of the planetary interpretation of TOI-1272 c

L. Mancini, L. Naponiello, M. Damasso et al. (+14 more)

Hot Neptunes are close-in exoplanets that occupy a sparsely populated region of parameter space known as the "hot-Neptune desert". Their presence in this extreme environment is puzzling as it implies a complex history involving intense stellar radiation, atmospheric loss, and unique migration patterns, different from Neptunes at larger orbital periods. We are running an observational programme conceived to enlarge the number of close-in Neptune-sized planets, with well-measured physical and orbital parameters, with the aim of contributing to obtaining a statistically significant sample needed to clarify what the formation and migration pathways of this class of exoplanets are. We used currently available TESS photometry, along with new (HARPS-N) and archival (HIRES) high-precision radial-velocity measurements, to review the main properties of the planetary systems TOI-1272 and TOI-1694 by means of joint-fit analyses that, in the case of TOI-1272, included Gaussian-process regressions for carefully modelling stellar activity. Our final estimates of the parameters of the two systems are consistent with previous measurements but have smaller uncertainties. We identified the radial-velocity variation of TOI-1272 found in the HIRES data as stellar activity rather than planetary in nature and, therefore, rejected the non-transiting planet TOI-1272c. This opens up the possibility that TOI-1272b's eccentricity is the result of high-eccentricity migration. The larger number of data at our disposal also allowed us to point out that both TOI-1694b and TOI-1694c move on slightly eccentric orbits. The current orbital architecture of TOI-1694 suggests a history of migration driven by both disc and dynamical interactions.
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All authors L. Mancini, L. Naponiello, M. Damasso, K. Biazzo, A. S. Bonomo, A. F. Lanza, J. Lillo-Box, M. Pinamonti, R. Cosentino, A. Bignamini, W. Boschin, A. Fiorenzano, P. Giacobbe, F. Manni, M. Rainer, G. Scandariato, A. Sozzetti

Solar and Stellar Astrophysics

Transonic Solutions for Recombination-Driven Stellar Winds

Ilan Strusberg, Re'em Sari and Jim Fuller

We present an analytical stationary isentropic solution of the spherically symmetric Euler equations in the gravitational field of a star using an equation of state of ionizable monatomic gas. The solution consists of a fully ionized hydrostatic inner region, followed by a thick hydrostatic recombination region where the density decreases by orders of magnitude, the radius increases by about an order of magnitude and the temperature decreases by a factor of two. Within this recombination region, a large portion of the recombination energy is used for lifting the gas subsonically. This region ends at a critical point, located roughly at $10-100~\rm{AU}$, where the gas is mostly recombined, beyond which it flows supersonically as a wind. We find the position and the quantities of the gas at the critical point and derive the mass-loss rate of the solution. We apply our solution to evolved stars, with a compact core surrounded by a high entropy envelope. We derive the mass-loss rate as a function of time. As the star is losing mass, it goes through a sequence of our solutions, in a runaway manner which ends once most of the high entropy envelope is lost. The recombination-driven winds are initiated once the stars expands to a radius of about $1~\rm{AU}~M/M_\odot$ and are terminated on a timescale of $10^1-10^4~\rm{years}$. We discuss the implications for common envelope evolution.
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High Energy Astrophysical Phenomena · Cross-listed from nucl-th

Hyperonic equation of state for neutron stars: A systematic Bayesian comparison of density-dependent and non-linear relativistic mean-field models

Pedro Sanson, Tuhin Malik and Constança Providência

A systematic Bayesian inference study of the equation of state (EOS) of dense matter with strangeness is presented, extending five relativistic mean-field (RMF) models with both constant and density-dependent couplings to include the full baryon octet. The hyperon-nucleon couplings in the scalar channel are varied within ranges informed by hypernuclear data, while vector isoscalar couplings are fixed by the SU(6) symmetry quark model. Observational constraints from NICER (PSR J0030, J0437, J0740) and GW170817, theoretical constraints from chiral effective field theory ($\chi$EFT) and perturbative QCD (pQCD), and experimental constraints from nuclear saturation properties are imposed simultaneously. We find that the inclusion of hyperons systematically reduces the maximum neutron star mass by $0.05$-$0.10,M_\odot$ across all models while increasing the radius at $1.4,M_\odot$ by $0.5$-$0.8$ km. The speed of sound exhibits a characteristic softening at densities $2$-$3,\rho_{\rm sat}$ coinciding with hyperon onset. All hyperonic models remain consistent with the $2,M_\odot$ constraint. Models with a more flexible isovector channel span a larger proton fraction when only nucleons are included. However, the extra flexibility is visibly suppressed by hyperons, meaning that the average proton distribution is independent of model flexibility when hyperons are included. Less flexible models show comparable or slightly increased proton fractions due to EOS stiffening when hyperons are included. Only a residual number of hyperonic equations of state give rise to a mass-radius curve with a negative slope at low masses. A $1.8,M_\odot$ neutron star with a radius larger than or similar to the radius of a $1.2,M_\odot$ star would provide strong evidence that the star contains baryonic degrees of freedom beyond nucleons.
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Astrophysics of Galaxies

Little Red and Blue Dots: AGN-excited narrow lines, Lyman-$\alpha$ emission, and resemblance to standard quasars

Sophia Geris, Roberto Maiolino, Xihan Ji et al. (+35 more)

We present an analysis of a sample of 36 Little Red and Blue Dots (LRDs and LBDs) at $2.26<z<7.89$, identified by JWST in the GOODS fields. While both categories are selected to have broad Balmer lines, both of them are extremely X-ray weak. Both classes share the same location on various diagnostic diagrams, consistent with AGN excitation (with some deviations which can be ascribed to low metallicity), although their weak HeII emission suggests a generally softer ionizing spectrum than ordinary AGN. LRDs display Ly$\alpha$ emission stronger than normal star-forming galaxies, and with a broad component consistent with the broad component of H$\alpha$. Overall, these findings indicate that LRDs and LBDs are both powered by growing black holes and their ionizing radiation escapes to ionize the surrounding interstellar medium (ISM). The broad Balmer lines ($H\alpha_b$ and $H\beta_b$) have different apparent properties: LBDs have EW(H$\alpha _b$) and $H\alpha_b/H\beta_b$ broadly consistent with normal AGN, while LRDs have higher values of both quantities, although still in the tail of the quasars distribution. LRD models in which a gas envelope completely encases the black hole, are inconsistent with these results – these scenarios need modification to include clumpiness, or a (classical) equatorial geometry, letting ionizing photons reach the ISM. The different broad Balmer properties imply that LBDs cannot simply be LRDs with more galaxy contribution. Scenarios in which LRDs are simply dust-obscured LBDs seem broadly consistent with the observations. Finally, these results indicate that LRDs' bolometric luminosities estimated assuming isotropic emission and complete covering by the absorber are inadequate. The few X-ray-detected LRDs suggest no deviation from the standard AGN bolometric corrections, once absorption is accounted for.
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All authors Sophia Geris, Roberto Maiolino, Xihan Ji, Guido Risaliti, Giorgio Lanzuisi, Francesco D'Eugenio, Yuki Isobe, Gareth Jones, Anishya Harshan, Matilde Brazzini, Ignas Juodžbalis, Jan Scholtz, Pierluigi Rinaldi, Hannah Übler, William Baker, Andrew J. Bunker, Marcella Brusa, Stefano Carniani, Stephane Charlot, Mirko Curti, Andrea Comastri, Emma Curtis Lake, Roberto Gilli, Kevin Hainline, Piero Madau, Stefano Marchesi, Giovanni Mazzolari, Lorenzo Napolitano, Eleonora Parlanti, Laura Pentericci, Cristina Ramos Almeida, Brant Robertson, Maddie S. Silcock, Roberta Tripodi, Giacomo Venturi, Cristian Vignali, Fabio Vito, Yongda Zhu

Earth and Planetary Astrophysics

Investigation of Split Comet 240P/NEAT

David Jewitt, Jane Luu and Yoonyoung Kim

We present time-series observations of the split comet 240P/NEAT near perihelion, obtained using the Nordic Optical Telescope. The brighter component, 240P-A, has an estimated radius in the range 400 m to 600 m, and loses dust at the peak rate 130 kg/s. The ejected dust has characteristic size 50 micron, is expelled sunward at 25 m/s, with a total ejected mass in the period of observation 1.5x10^9 kg. Mass loss from the fainter component, 240P-B, peaks at 35 kg/s and the total ejected mass was 2.3x10^8 kg. The radius of 240P-B is uncertain, with a best estimate about 300 m and an absolute lower limit 50 m. 240P-A and 240P-B are currently separating at about 1 m/s, a speed that is likely accelerating as a result of differential outgassing forces, and have a separation age over 3 years. The splitting of 240P is incompatible with the action of tides, impact, and internal pressure build up. 240P fits a developing picture, in which small comets are destroyed by rotational instabilities triggered by outgassing torques, an explanation that can be tested in 240P by future observations.
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Instrumentation and Methods for Astrophysics

On-orbit Calibration of the Carruthers GCI: Instrument Effect Correction

Alex Zhang, Heather Filippini, Lara Waldrop et al. (+1 more)

The Carruthers Geocorona Observatory – launched in September 2025 – is NASA's first mission devoted to investigating the fundamental nature of Earth's exosphere from its distant vantage in halo orbit around the Earth-Sun L1 Lagrange point. Its primary payload, the GeoCoronal Imager, consists of two coaligned photometric imagers that measure ultraviolet Lyman-alpha emission radiance from exospheric hydrogen simultaneously at wide- and narrow- fields of view. The imagers use Micro Channel Plate intensified Complimentary Metal Oxide Semiconductor detectors, which are known to add various artifacts to the final image telemetered from the spacecraft, hereby known as instrument effects. This paper details the algorithms used to retrieve and remove instrument effects from raw telemetry on-orbit, including detector voltage bias, thermal dark current, particle radiation, flat-field, and distortion. Finally, the science data processing pipeline from raw telemetry to instrument-effect corrected images is detailed. Algorithm performance is measured via a synthetic numerical image generator or validated on pre-launch experiments.
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All authors Alex Zhang, Heather Filippini, Lara Waldrop, Jason McPhate

Cosmology and Nongalactic Astrophysics · Cross-listed from physics.hist-ph

Cosmology as Representation: Informational Invariance and the Limits of Scientific Realism

Stefano Profumo

Modern cosmology is often taken to provide an increasingly accurate description of the universe's underlying ontology through progressively refined mathematical models. I challenge this interpretation by arguing that the empirical success of cosmology underdetermines not only ontology but also the mathematical and conceptual frameworks used to represent observational data. I propose instead that the objective content of cosmology is best identified with cross-representational informational invariants-features of observational structure that persist across empirically adequate descriptions. These invariants can be characterized in information-theoretic terms, including correlation structure, statistical distinguishability, and limits on accessible information, and formalized using tools such as the Fisher-Rao metric on model space. On this view, cosmological models are best understood as efficient encodings of observational structure rather than uniquely privileged descriptions of fundamental reality. Scientific progress, accordingly, consists not in convergence toward a fixed ontology, but in the progressive refinement of the informational structure accessible to observation.
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Instrumentation and Methods for Astrophysics

Development of TIFUUN: Terahertz Integral Field Units with Universal Nanotechnology

Akira Endo, Tom J. L. C. Bakx, Jochem J. A. Baselmans et al. (+50 more)

TIFUUN (THz Integral Field Units with Universal Nanotechnology) is an ultra-wideband mm-submm wave imaging spectrometer that capitalizes on the highly scalable integrated superconducting spectrometer technology. TIFUUN has two slots for integral field units (IFUs), which can jointly be optimized as open-hardware for each astronomical observation in terms of spatial and spectral coverage. These IFUs can have observation frequencies in the range of 90–360 GHz, with spectral resolution up to $R\equiv F/\Delta F \le 1,000$, with up to $\sim$18,000 kinetic inductance detectors (shared by the two IFUs with a flexible ratio). The ultra-wide 4:1 (2 octave) bandwidth optics fits in a remarkably compact volume, by means of thin silicon lenses and a high chief ray angle design. The first pair of IFUs are being developed for the SUBLIME (Study of the Universe By Line Intensity Mapping Experiments) experiment that aims to map CII emission at redshift $\sim$6 to trace the cosmic large-scale structure and the buildup of galaxies during reionization, using TIFUUN on the ASTE 10-m telescope. The scalability, flexibility and compactness makes TIFUUN a highly compatible and portable system suited also for upcoming telescope facilities in the vicinity, such as FYST and AtLAST/LST.
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All authors Akira Endo, Tom J. L. C. Bakx, Jochem J. A. Baselmans, Dries Boleij, Stefanie A. Brackenhoff, Bernhard R. Brandl, Martino Calvo, Shahab O. Dabironezare, Hans van der Does, Rei Enokiya, Sho Fujisawa, Shinji Fujita, Enrico Garaldi, Wouter Gregoor, Masato Hagimoto, Davit Hakobyan, Angelina Harke-Hosemann, Robert Huiting, Shiro Ikeda, Reinier M. J. Janssen, Kenichi Karatsu, Nick de Keijzer, Kotaro Kohno, Takumi Kojima, Alkistis Kyriakidou, Louis H. Marting, Tomotake Matsumura, Cory Meijneke, Tetsuhiro Minamidani, Arend Moerman, Alessandro Monfardini, Kana Moriwaki, Kanako Narita, Yuri Nishimura, Erika Ogata, Leon G. G. Olde Scholtenhuis, Tristan Oude Essink, Jim R. Piek, Matus Rybak, Kana Sakaguri, Seiichi Sakamoto, Aurora Simionescu, Nikita A. Soshnin, Tatsuya Takekoshi, Yoichi Tamura, Akio Taniguchi, David J. Thoen, Sten Vollebregt, Lingyu Wang, Paul P. van der Werf, Stephen J. C. Yates, Naoki Yoshida, Silvia Zhang

Earth and Planetary Astrophysics

Environmental interactions in Class II systems and their impact on the disk-planet architecture

Pedro P. Poblete, Nicolás Cuello, Tim D. Pearce et al. (+4 more)

Protoplanetary disks evolve in clustered environments where interactions with nearby stars and interstellar gas are common. Such environmental processes, including stellar flybys and gas infall, can significantly perturb disk structures over the disk lifetime and potentially influence the evolution of embedded planets. We investigate how environmental interactions affect the architecture of Class II systems that host both a disk and already-formed planets, and assess their impact on disk structure and dynamics, as well as planetary evolution. We performed 3D simulations using the Phantom SPH code, including multiple dust species treated with a dust-as-particles approach that accounts for dust back-reaction on the gas. We modeled a disk hosting two planets in a 2:1 mean-motion resonance and subjected the system to two types of perturbations: an infalling gaseous cloudlet and a stellar flyby. Infall and flyby perturbations change the disk morphology and dynamical state. Infalling gas increases the disk mass and angular momentum, dynamically exciting the dust and producing eccentric, multi-ring dust structures. The stellar flyby truncates the disk, compacting the dust distribution radially and enhancing episodic radial migration of dust grains. These processes excite eccentricity in both gas and dust, leading to distinct accretion pathways for the planets. In particular, the flyby promotes inward dust migration, which may enhance solid accretion onto the planets, while infall preferentially increases the accretion rate of the inner planet. Environmental interactions during the Class II phase can reshape disk-planet systems, imprinting dynamical signatures that may persist into later evolutionary stages. Both late infall and stellar flybys influence the growth and composition of planets; in particular, infall events can lead to the formation of eccentric, narrow debris disks.
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All authors Pedro P. Poblete, Nicolás Cuello, Tim D. Pearce, Antoine Alaguero, Josh Calcino, Daniel J. Price, Michael Kuffmeier

Earth and Planetary Astrophysics

Implications of self-consistent H$_2$O ice optical constants on radiative transfer models of disks

Z. L. Smith, M. K. McClure, I. Kamp et al. (+1 more)

Interstellar water (H$_2$O) ice exhibits significantly varied profiles over its spectral features with temperature and thermal history. No previous radiative transfer model of a protoplanetary disk has fully accounted for these effects over 3 - 200$\mu$m simultaneously. A radiative transfer model with region-based distribution of ices and applicable ice optical constant composites (OCCs) is required to properly model the distribution and spectral signatures of water ice in disks. We build such H$_2$O ice OCCs by combining multiple experiment measurements of the imaginary refractive indices, $k$, to cover from 0.1 - 10,000$\mu$m and perform Kramers-Kronig (KK) integrations to derive updated real refractive indices, $n$. We construct H$_2$O ice OCCs for two thermal histories: first, direct deposit and measure at a fixed temperature ices (DT) and deposit and cool down (DC) ices, for five and eight distinct temperatures, respectively. Next, we self-consistently apply these within a radiative transfer model of a protoplanetary disk according to its thermal structure. This produces the first self-consistent RT profiles for the two most commonly used spectroscopic tracers of thermal processing of H$_2$O ice. To assess the impact that appropriate H$_2$O optical constants have on the 3$\mu$m absorption and 45 and 63$\mu$m emission profiles, we run four RADMC-3D radiative transfer models of edge-on class II disk, HH 48 NE. The four models each use different OCCs; the standard single temperature crystalline and amorphous H$_2$O ice OCCs available from OpTool and our own multi-temperature DT set of OCCs and DC only set of OCCs. We find that ices must have been thermally processed at temperatures higher than the local disk temperature in order to produce crystalline spectral profiles at 3, 45 or 63$\mu$m in disks, suggesting local heating events or outward transport to colder regions.
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All authors Z. L. Smith, M. K. McClure, I. Kamp, S. M. Cazaux

Cosmology and Nongalactic Astrophysics

Wave-optics imprints of dark matter subhalos on strongly lensed gravitational waves. II. Saddle images and detectability

Shin'ichiro Ando

Wave-optics interference in strongly lensed gravitational waves is a new interferometric probe of dark matter substructure: a subhalo population threading a galaxy-scale lens imprints frequency-dependent distortions on the amplification factor of each macro image. In a companion paper (arXiv:2603.04267), we computed these imprints for the magnified minimum image. Here, we extend the calculation to the saddle-point image and we assess the detectability of the combined signal with the Laser Interferometer Space Antenna (LISA). Evaluating the amplification factor at a saddle is numerically delicate, because the equal-arrival-time contours are open and the subhalo signal is a small difference of large terms; we present a time-domain method that resolves it. Across a Monte Carlo ensemble of cold dark matter subhalo realizations, subhalos induce percent-level amplitude and phase modulations in both image parities, while the mean (de)magnification splits by parity: the minimum is net magnified and the saddle net demagnified. Demodulating the macro-image interference recovers the per-image modulations, and a matched-filter analysis that projects out the lens parameters yields a combined detection above $5\sigma$ in $62\%$ of realizations for fiducial massive-black-hole-binary sources of total mass $\sim10^{6}\,M_\odot$ at redshift $1.5$, provided the source lies close to the lens caustic at small impact parameter $y_{\rm src}\lesssim0.1$. Folding these naive per-event significances through optimistic strong-lensing rate forecasts yields $10$-$20$ substructure detections over the LISA mission. Strongly lensed gravitational waves are thus a sensitive, complementary probe of substructure at $10^{4}$-$10^{7}\,M_\odot$ scales inaccessible to electromagnetic observations.
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Cosmology and Nongalactic Astrophysics

Are Cosmological Data Excluding Sterile Neutrinos or Only the Fully Thermalized Limit?

Artur Ladeira, Rafael C. Nunes, Eleonora Di Valentino et al. (+1 more)

We present a cosmological reassessment of light sterile-neutrino scenarios, examining whether current observations exclude sterile neutrinos as a class or primarily constrain the fully thermalized case. We consider three distinct realizations: (i) a fully thermalized sterile species (FTS), (ii) a different-temperature sterile-neutrino thermal relic (DTS) relative to the active neutrino background and (iii) a Dodelson–Widrow-like (DW) sterile neutrino with reduced phase-space normalization. Constraints are derived within both $\Lambda$CDM and the CPL dynamical dark-energy framework using combinations of Planck-CMB data, DESI DR2 BAO measurements, and the PantheonPlus and Union3 Type Ia supernova samples. For baseline data combinations without a local $H_0$ prior, the FTS scenario is strongly disfavored in both cosmological models. Adding the local $H_0^{\rm DN}$ prior allows $\Lambda$CDM+FTS to accommodate the high local $H_0$ value and become statistically competitive with standard $\Lambda$CDM once SNIa data are included, although the sterile-neutrino mass remains consistent with zero. By contrast, partially populated sterile-neutrino scenarios remain viable: the DW realization is broadly compatible with current observations, while the DTS scenario yields the least cosmological pressure among the cases considered. Overall, cosmological data mainly require a strongly suppressed effective sterile abundance, leading to tight constraints on \textbf{$m_s^{\rm eff}$} while allowing substantially weaker bounds on the physical sterile mass. We conclude that current observations do not generically exclude sterile neutrinos, but rather place strong pressure on fully thermalized or highly populated scenarios, highlighting the importance of production history and phase-space distribution when interpreting cosmological constraints.
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All authors Artur Ladeira, Rafael C. Nunes, Eleonora Di Valentino, Stefano Gariazzo

Astrophysics of Galaxies

X-ray emission maps and scaling relations in IllustrisTNG and MillenniumTNG: Differences between cluster and group regimes

Franklin Aldás, Facundo A. Gómez, Volker Springel et al. (+3 more)

X-ray observations are a primary probe of the intracluster medium, widely used to infer galaxy cluster masses and scaling relations. We present and validate a pipeline to generate X-ray emission maps of galaxy groups and clusters from large cosmological simulations, and use it to study the origin of deviations from self-similarity across the group-to-cluster transition. We apply this pipeline to the Illustris-TNG300 and MillenniumTNG simulations, constructing \mbox{X-ray} emission maps and spectra based on APEC cooling functions. For simulations that do not explicitly track individual chemical abundances, we introduce a metallicity-based prescription that accurately reproduces the full spectral emission. We derive the $L_{\mathrm{X}}$–$M_{500}$, $M_{\mathrm{gas}}$–$M_{500}$, and $T$–$M_{500}$ scaling relations over $10^{12.5} \leq M_{500} \leq 10^{15.5}\,\mathrm{M}_\odot$, compare them with observational data, and quantify the hydrostatic equilibrium and spectroscopic temperature biases through synthetic X-ray analyses. The simulated scaling relations are in good overall agreement with observations and are best described by broken power laws with a pivot at $M_{500}=10^{13.67}\,\mathrm{M}_\odot$. At high masses, the slopes are close to self-similar expectations; at lower masses the relations steepen significantly, reflecting the growing importance of AGN feedback. X-ray hydrostatic masses are systematically underestimated by $15\%$, independently of cluster mass. When spectroscopic effects are included, the bias becomes mass-dependent, ranging from $15\%$ at low masses to $21\%$ at high masses. The recovered X-ray luminosity, measured in the $0.15$–$1\,R_{500}$ aperture, is also mass-dependent: high-mass clusters are underestimated by $18\%$, while low-mass systems show discrepancies of up to $33\%$, driven by single-temperature spectral modelling of the gas outside the core.
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All authors Franklin Aldás, Facundo A. Gómez, Volker Springel, Rüdiger Pakmor, Alex Saro, Tiago Castro

High Energy Astrophysical Phenomena · Cross-listed from gr-qc

Relativistic effects in extreme-mass-ratio inspirals within scalar clouds: Eccentric and inclined orbits

Qi-Xuan Xu, Richard Brito, Riccardo Della Monica et al. (+2 more)

We study extreme-mass-ratio inspirals (EMRIs) evolving in a scalar cloud environment that may form through superradiant instabilities, using a fully relativistic perturbative framework that allows for eccentric and inclined orbits. EMRIs, consisting of a stellar-mass compact object inspiraling into a supermassive black hole, are key sources for space-based gravitational-wave detectors such as LISA. Previous relativistic studies of EMRIs in scalar clouds have been restricted to circular, equatorial motion. Here, instead, we focus on a Schwarzschild black hole background to incorporate eccentricity and orbital inclination. By computing the scalar energy and angular momentum scattered off to spatial infinity and absorbed at the event horizon, we show that orbital eccentricity can induce a dense spectrum of resonances near the last stable orbit, associated with strong relativistic apsidal precession. We further find that orbital inclination can significantly modify the orbital energy and angular momentum losses. In particular, we identify a critical inclination angle below which, at sufficiently small orbital radii, there is a net transfer of energy from the scalar cloud to the orbit. Moreover, for sufficiently large eccentricities, resonances associated with relativistic apsidal precession persist across the full range of inclinations, although their structure changes significantly between prograde and retrograde orbits. These results provide a foundation for future studies of EMRIs in scalar cloud environments on fully generic orbits around spinning black holes.
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All authors Qi-Xuan Xu, Richard Brito, Riccardo Della Monica, Rodrigo Vicente, Chen Yuan