Peer Revenue Impact factor: volatile

Papers

Fresh from arXiv, typeset properly. Highlighted words trade on the market.

Physics Astrophysics

astro-ph Watch Astrophysics

Wednesday 15 October

Instrumentation and Methods for Astrophysics

First Demonstration of Kernel Phase Interferometry on JWST/MIRI: Prospects for Future Planet Searches Around Post Main Sequence Stars

Chelsea Adelman, Steph Sallum, Matthew De Furio et al. (+1 more)

Kernel phase interferometry (KPI) is a post-processing technique that treats a conventional telescope as an interferometer by accurately modeling a telescope pupil as an array of virtual subapertures. KPI provides angular resolution within the diffraction limit by eliminating instrumental phase errors to first order. It has been successfully demonstrated to boost angular resolution on both space- and ground-based observatories, and is especially useful for enhancing space telescopes, as their diameters are smaller than the largest ground-based facilities. Here we present the first demonstration of KPI on JWST/MIRI data at 7.7 microns, 10 microns, and 15 microns. We generate contrast curves for 16 white dwarfs from the MIRI Exoplanets Orbiting White dwarfs (MEOW) Survey, finding significantly deeper contrast at small angular separations compared to traditional imaging with JWST/MIRI, down to within $\lambda$/D. Additionally, we use our KPI setup to successfully recover four known companions orbiting white dwarfs and brown dwarfs. This analysis shows that at these wavelengths KPI can uniquely access the orbital parameter space where inward-migrating post-main-sequence giant exoplanets are now thought to exist. We discuss the prospects for applying KPI to a larger sample of white dwarfs observed with JWST, increasing the volume of directly imaged close-in post-main-sequence exoplanets.
Read the full abstract

All authors Chelsea Adelman, Steph Sallum, Matthew De Furio, Josh Eisner

Tuesday 14 October

Instrumentation and Methods for Astrophysics

Improved Absolute Polarization Calibrator for BICEP CMB Polarimeters

A. R. Polish, P. A. R. Ade, Z. Ahmed et al. (+89 more)

Cosmic birefringence is a hypothesized parity violation in electromagnetism that predicts a frequency-independent polarization rotation as light propagates. This would rotate the light from the Cosmic Microwave Background, producing an unexpected EB correlation. However, cosmic birefringence angle is degenerate with instrument polarization angle, and breaking this degeneracy requires an absolute polarization calibration. We calibrate the BICEP3 telescope (a 95GHz CMB polarimeter) by observing a rotating polarized source (RPS) with both the telescope and a small test receiver called the In-Situ Absolute Angle Calibrator (ISAAC).
Read the full abstract

All authors A. R. Polish, P. A. R. Ade, Z. Ahmed, M. Amiri, D. Barkats, R. Basu Thakur, C. A. Bischoff, D. Beck, J. J. Bock, H. Boenish, V. Buza, B. Cantrall, J. R. Cheshire IV, J. Connors, J. Cornelison, M. Crumrine, A. J. Cukierman, E. Denison, L. Duband, M. Echter, M. Eiben, B. D. Elwood, S. Fatigoni, J. P. Filippini, A. Fortes, M. Gao, C. Giannakopoulos, N. Goeckner-Wald, D. C. Goldfinger, S. Gratton, J. A. Grayson, A. Greathouse, P. K. Grimes, G. Hall, G. Halal, M. Halpern, E. Hand, S. A. Harrison, S. Henderson, T. D. Hoang, J. Hubmayr, H. Hui, K. D. Irwin, J. H. Kang, K. S. Karkare, S. Kefeli, J. M. Kovac, C. Kuo, K. Lasko, K. K. Lau, M. Lautzenhiser, A. Lennox, T. Liu, S. Mackey, N. Maher, K. G. Megerian, L. Minutolo, L. Moncelsi, Y. Nakato, H. T. Nguyen, R. O'Brient, S. N. Paine, A. Patel, M. A. Petroff, T. Prouve, C. Pryke, C. D. Reintsema, T. Romand, M. Salatino, A. Schillaci, B. Schmitt, B. Singari, A. Soliman, T. St. Germaine, A. Steiger, B. Steinbach, R. Sudiwala, K. L. Thompson, C. Tsai, C. Tucker, A. D. Turner, C. Verges, A. G. Vieregg, A. Wandui, A. C. Weber, J. Willmert, W. L. K. Wu, H. Yang, C. Yu, L. Zheng, C. Zhang, S. Zhang

High Energy Astrophysical Phenomena

Exploring the connection between compact object mergers and fast X-ray transients: The cases of LXT 240402A and EP250207b

R. L. Becerra, Yu-Han Yang, Eleonora Troja et al. (+29 more)

The connection between compact object mergers and some extragalactic fast X-ray transients (FXRTs) has long been hypothesized, but never ultimately established. In this work, we investigate two FXRTs, the LEIA X-ray Transient LXT 240402A and the Einstein Probe EP250207b, whose precise positions lie close to nearby ($z\!\lesssim\!0.1$) quiescent galaxies with negligible probability of chance coincidence, identifying them as particularly promising cases of merger-driven explosions in the local Universe. We used Chandra to derive accurate localizations for both events and secure otherwise ambiguous associations with their optical counterparts. Deep optical and near-infrared observations with VLT, GTC, and LBT were performed to characterize the surrounding environment and search for kilonova emission, the hallmark of neutron star mergers. Complementary early-time X-ray monitoring with Swift and Einstein Probe was used to constrain the non-thermal afterglow. We find that both FXRTs remain compatible with a compact binary merger progenitor, which produced low-mass ejecta and kilonova emission subdominant to the afterglow. However, alternative explanations such as a distant ($z\!\gtrsim\!1$) core-collapse supernova cannot be conclusively ruled out.
Read the full abstract

All authors R. L. Becerra, Yu-Han Yang, Eleonora Troja, Massine El Kabir, Simone Dichiara, Niccolò Passaleva, Brendan O'Connor, Roberto Ricci, Chris Fryer, Lei Hu, Qinyu Wu, Muskan Yadav, Alan M. Watson, Anastasia Tsvetkova, Camila Angulo-Valdez, María D. Caballero-García, Alberto J. Castro-Tirado, C. C. Cheung, Dmitry Frederiks, Maria Gritsevich, J. E. Grove, M. Kerr, William H. Lee, Alexandra L. Lysenko, Margarita Pereyra Talamantes, Anna Ridnaia, Rubén Sánchez-Ramírez, Hui Sun, Dmitry Svinkin, Mikhail Ulanov, R. Woolf, Bing Zhang

Solar and Stellar Astrophysics

Beyond OCCAM: Measuring Optical Neutron Capture Abundances of Open Cluster Stars

Natalie Myers, Sarah Loebman, Henrique Reggiani et al. (+1 more)

Open clusters have long been used to determine ages of stars, as well as calibrate stellar evolution models and other methods of age-dating stellar groups, e.g., gyrochronology, asteroseismology, and chemical clocks. In this work, we have obtained new high-resolution (R $\ge$ 50,000), high-S/N, optical data for 3+ stellar members in open clusters, using Keck/HIRES, with membership derived from the Open Cluster Chemical Abundances and Mapping (OCCAM) survey. From these new Keck/HIRES data, we have derived neutron capture abundances for stars in seven distant outer Galaxy open cluster
Read the full abstract

All authors Natalie Myers, Sarah Loebman, Henrique Reggiani, Peter Frinchaboy

Astrophysics of Galaxies

Probing the magneto-ionic medium of the Milky Way using pulsars

Saakshi Dhakal and Amit Seta

Magnetic fields are fundamental to the dynamics of the interstellar medium (ISM) in spiral galaxies and are often separated into large-scale, regular ($\boldsymbol{B}$) and small-scale, random ($\boldsymbol{b}$) components. The thermal electron density, $n_{\rm e}$, can also be divided into large-scale, diffuse, $\langle n_{\rm e} \rangle$, and small-scale, clumpy, $\delta n_{\rm e}$, components. Estimating the properties of $b$ and $\delta n_{\rm e}$ from observations, even within the Milky Way, has long been challenging. This work addresses the challenge using pulsars, which probe the Milky Way's magneto-ionic medium. Using data of more than 1200 pulsars from the Australia Telescope National Facility pulsar catalogue, we combine dispersion (${\rm DM}$) and rotation (${\rm RM}$) measures with theoretical models to estimate both small- and large-scale properties of the Galactic magnetic field and thermal electron density. We find no significant correlation between the average parallel magnetic field strength, $\langle B_{\parallel} \rangle [\mu{\rm G}] = 1.232\,{\rm RM}\,[{\rm rad\,m^{-2}}]/{\rm DM}\,[{\rm pc\,cm^{-3}}]$, and pulsar distance. For pulsars within $20\,{\rm kpc}$, we estimate $|B| \approx 1.2\,\mu{\rm G}$ and $\langle n_{\rm e} \rangle \approx 0.05\,{\rm cm}^{-3}$. More importantly, we determine correlation lengths of small-scale components, $\ell_{b} \approx 20$ – $30\,{\rm pc}$ and $\ell_{\delta n_{\rm e}} \approx 250$ – $300\,{\rm pc}$. At smaller distances, $B$ remains roughly constant, while $\langle n_{\rm e} \rangle$ increases and both length scales decrease. These results refine our understanding of fundamental scales in the magneto-ionic medium, aiding the interpretation of extragalactic ${\rm RM}$s and providing insights into the role of magnetic fields in galaxies.
Read the full abstract

Cosmology and Nongalactic Astrophysics

When Tiny Halos Stir Spacetime: Gravitational Waves from Fifth-Force Mergers

Xinpeng Wang, Yifan Lu, Zachary S. C. Picker et al. (+2 more)

Dark matter fermions interacting via attractive fifth forces mediated by a light mediator can form dark matter halos in the very early universe. We show that bound systems composed of these halos are capable of generating gravitational wave (GW) signals detectable today, even when the individual halos are very light. The Yukawa force dominates the dynamics of these halo binaries, rather than gravity. As a result, large GW signals can be produced at initially extremely high frequencies, which are then redshifted to frequency bands accessible to current or future GW observatories. In addition, the resulting GW signals carry distinctive features that enable future observations to distinguish them from conventional ones. Notably, even if only a tiny fraction of dark matter experiences strong fifth-force interactions, such effects provide a new avenue to discover self-interacting dark matter through GW observations.
Read the full abstract

All authors Xinpeng Wang, Yifan Lu, Zachary S. C. Picker, Alexander Kusenko, Misao Sasaki

High Energy Astrophysical Phenomena

Galactic X-ray Transients in the First eROSITA All Sky Survey

Vikash Maan, Aman Katira and Kunal. P. Mooley

Although a multitude of studies have focused on targeted observations of Galactic X-ray transients, blind surveys and population studies have been limited. We have used the ROSAT, eROSITA and Gaia source catalogs to find Galactic X-ray transients having timescales $<$30 years. We report the properties of 738 transients found in our search, majority of which are active stars or interacting binaries. We have also found $\sim$40 compact object systems among which are at least 8 newly-identified white-dwarf systems, 3 known X-ray binaries, and one known pulsar. We use eROSITA (soft X-ray) spectra of the Galactic transients to show that two distinct types of flaring systems are prevalent: one having peak around 1 keV, well fit by thermal models, and another having peak below 0.2 keV and requiring a power-law component. Our study also reveals that single star or interacting binary systems (X-ray transients) involving giant stars exhibit significantly higher X-ray luminosities than systems involving only main-sequence stars or young stellar objects. Finally, we discuss the properties of the transients in the context of their putative emission mechanisms, the fraction of transients with respect to the total population, and the rates of Galactic transients expected in blind searches of the X-ray sky.
Read the full abstract

Instrumentation and Methods for Astrophysics

Toward First-Principles Multi-Messenger Predictions: Coupling Nuclear Networks with GR Radiation-MHD in Gmunu

Patrick Chi-Kit Cheong and Christopher L. Fryer

We present a new implementation of nuclear reaction networks in the General-relativistic multigrid numerical (Gmunu) code, a framework for general relativistic radiation magnetohydrodynamics (GRRMHD). The extended code self-consistently evolves nuclear species coupled to hydrodynamics, magnetic fields, and neutrino radiation transport under the conformal flatness approximation to Einstein's equations. Four approximate nuclear networks are included, with stiff source terms integrated using implicit-explicit Runge-Kutta schemes. Validation is performed through benchmarks including conserved-to-primitive recovery with a tabulated stellar equation of state, one-zone silicon burning, and hydrodynamic tests of shock tubes, acoustic pulses, and detonation fronts of Type Ia supernovae. These tests confirm accurate coupling between nuclear reactions and fluid dynamics, conserving electron and nuclear mass fractions to machine precision. As an application, we conduct spherically symmetric core-collapse supernova simulations. The models reproduce the expected non-exploding behavior of standard progenitors, while enhanced neutrino heating revives the shock. Including nuclear burning modifies the post-shock composition and dynamics, converting silicon and oxygen layers into iron-group nuclei and strengthening the explosion. This demonstrates the impact of explosive burning on ejecta composition and shock evolution, and establishes the stability of the coupled GR radiation-MHD-nuclear framework. The implementation is fully compatible with multidimensional GRMHD simulations and represents the first GRRMHD code combining M1 neutrino transport with fully coupled nuclear burning.
Read the full abstract

Solar and Stellar Astrophysics

High-Resolution Modelling of Coronae and Winds in Solar-type Stars with Varying Rotation Rates I. X-ray Coronae

Yue-Hong Chen, Julián D. Alvarado-Gómez, Xin Cheng et al. (+8 more)

Stellar coronae are believed to be the main birthplace of various stellar magnetic activities. However, the structures and properties of stellar coronae remain poorly understood. Using the Space Weather Modelling Framework with the Alfvén Wave Solar Model (SWMF-AWSoM) and dynamo-generated surface magnetic maps, here we model the coronae of four solar-type stars. By incorporating the Sun, our work covers a range of stars with the rotation varying from 1.0 to 23.3 $\Omega_\odot$ (periods of 25 to 1 days). Guided by observations, we scale the magnetic field strength with increasing rotation, covering a range between 6.0 G to 1200 G approximately. In our models, energy release associated with small-scale magnetic flux is a key source of coronal heating and is essential for reproducing realistic coronal structures. Our models capture dense (1$-$2 orders of magnitude higher than solar values) and ultra-hot ($\sim 10\,\mathrm{MK}$) coronae dominated by closed field structures. Using the CHIANTI atomic database, we also compute synthetic X-ray spectra and derive the corresponding X-ray luminosities $(L_X)$, which follow a scaling law to magnetic field $L_X \propto \langle|\mathbf{B}|\rangle^{1.75}$. Furthermore, the coronal X-ray emission is found to be rotationally modulated by the alternating presence of bright active regions and dark coronal holes. These results provide new insights into the extremely high-energy coronae of rapidly rotating solar-type stars, which differ markedly from the Sun.
Read the full abstract

All authors Yue-Hong Chen, Julián D. Alvarado-Gómez, Xin Cheng, Yu Dai, Tong Shi, Katja Poppenhäger, Chen Xing, Shun Inoue, Jörn Warnecke, Maarit J. Korpi-Lagg, Mingde Ding

High Energy Astrophysical Phenomena

Cosmic Ray Transport and Gamma-Ray Signatures in the Interstellar Medium

Lucas Barreto-Mota, Elisabete M. de Gouveia Dal Pino, Siyao Xu et al. (+4 more)

The interaction of cosmic rays (CRs) with magnetic fields and the interstelar medium (ISM) leads to the production of nonthermal radiation. Although this has been a topic of study for many years, it still poses many challenges to the understanding of these processes. In this work we present a short review of recent advances in the understanding of CR propagation in magnetohydrodynamical (MHD) turbulence, in particular the process of mirror diffusion, and how it can help explain recent observational constraints for CR diffusion away from sources. We also present preliminary results from Monte Carlo simulations of CR cascading and propagation within a young massive stellar cluster (YMSC), aimed at probing the origin of very-high-energy (VHE) emission from these sources.
Read the full abstract

All authors Lucas Barreto-Mota, Elisabete M. de Gouveia Dal Pino, Siyao Xu, Alexandre Lazarian, Rafael Alves-Batista, Gaetano Di Marco, Stela Adduci Faria

Instrumentation and Methods for Astrophysics

Simulation-Based Pretraining and Domain Adaptation for Astronomical Time Series with Minimal Labeled Data

Rithwik Gupta, Daniel Muthukrishna and Jeroen Audenaert

Astronomical time-series analysis faces a critical limitation: the scarcity of labeled observational data. We present a pre-training approach that leverages simulations, significantly reducing the need for labeled examples from real observations. Our models, trained on simulated data from multiple astronomical surveys (ZTF and LSST), learn generalizable representations that transfer effectively to downstream tasks. Using classifier-based architectures enhanced with contrastive and adversarial objectives, we create domain-agnostic models that demonstrate substantial performance improvements over baseline methods in classification, redshift estimation, and anomaly detection when fine-tuned with minimal real data. Remarkably, our models exhibit effective zero-shot transfer capabilities, achieving comparable performance on future telescope (LSST) simulations when trained solely on existing telescope (ZTF) data. Furthermore, they generalize to very different astronomical phenomena (namely variable stars from NASA's Kepler telescope) despite being trained on transient events, demonstrating cross-domain capabilities. Our approach provides a practical solution for building general models when labeled data is scarce, but domain knowledge can be encoded in simulations.
Read the full abstract

Astrophysics of Galaxies

Only the Special Survive: Evolution of Long-Lived Star Clusters in Galaxy Simulations

Alessa I. Wiggins, Sarah Loebman and Peter Frinchaboy

In this work, we aim to answer one crucial question behind the discrepancy between chemical trends of field stars and clusters in the Galactic disk: is the chemical gradient mismatch driven by cluster migration and differential survivability as a function of galactic location? To answer this question, we explored the evolution of long-lived (> 1 Gyr) star clusters in Milky Way-galaxy simulations. In particular, we investigated why some star clusters remain bound over billions of years. We have traced the unique trajectories for a sample of open clusters around two FIRE galaxies throughout cosmic time. Additionally, we characterized the small-scale environment surrounding these clusters over their orbital history. We see that clusters across both FIRE galaxies spend the majority of their lives in under-dense regions of gas, except for brief passages where they interact with gas clouds, causing their orbits to be altered.
Read the full abstract

Instrumentation and Methods for Astrophysics

J-PLUS: Turning Off the Bright Stars

Sepideh Eskandarlou, Mohammad Akhlaghi, Johan H. Knapen et al. (+23 more)

Photometric surveys require precise point spread function (PSF) characterization, as it varies across filters and is crucial for accurate photometry and low surface brightness (LSB) studies. However, the small PSF size provided by default pipelines suits only barely resolved objects, making it difficult to analyze regions near bright stars (rendering those regions unusable). These components are then combined to generate a final PSF for each exposure and filter, spanning 15 mag arcsec-2 in surface brightness and 4 arcmin in radius in the broad bands. In narrow-band filters, the J-PLUS PSF exhibits two rings, whereas in broad-band filters, only one ring is observed. Additionally, the position of the ring shifts with filter wavelength: as the filters become redder, the ring radius increases. We find that there is no significant variation in the extended PSF observed as a function of time (within 2.5h) or position in the field of view. The radial profile of NGC 4212 (which is close to a star) is also studied before/after PSF-subtraction. We developed a novel method to determine the central coordinates of saturated stars, and classify stars without using Gaia magnitudes. Additionally, mirror reflections are automatically detected and masked. Furthermore, in combining different stars and various components of the PSF, we avoided the use of a fixed radius by introducing a new method that does not depend on radial measurements. Accurate characterization of the extended PSF and its subtraction improves sky subtraction, increases the effective area of the survey by about 10%, and enables the study of extended large LSB features in wide area surveys like J-PLUS. Our pipeline is published as free software (GNU GPLv3) an can be customized to other surveys such as J-PAS, where its impact will be even greater due to its depth. This paper is fully reproducible and produced from Commit 4860c70.
Read the full abstract

All authors Sepideh Eskandarlou, Mohammad Akhlaghi, Johan H. Knapen, Carlos López-Sanjuan, Raúl Infante-Sainz, Helena Domínguez Sánchez, Zahra Sharbaf, Héctor Vázquez Ramió, Juan Antonio Fernández Ontiveros, César Iñiguez García, Tamara Civera Lorenzo, David José Muniesa Gallardo, Paula R.T. Coelho, Alessandro Ederoclite, Jesus Varela, Fran Jiménez-Esteban, A. Javier Cenarro, Antonio Marín-Franch, Renato A. Dupke, Mariano Moles, Carlos Hernández-Monteagudo, Rahna P.T., David Cristóbal-Hornillos, Jailson Alcaniz, Laerte Sodré Jr., Raul E. Angulo

2510.12940 · 14 Oct · Accepted for publication in A&A. Supplementary data on Zenodo (http://doi.org/10.5281/zenodo.17348653), project source on Gitlab (https://gitlab.com/Sepideh.Esk/psf-j-plus) and archived on Software Heritage (swh:1:dir:fc95ed9ad173de6fa64690e3d71ab041c630f32c; see text for usage). Abstract is summarized to fit arXiv limit

Abstract PDF $STAR ×6$GAIA ×1

Instrumentation and Methods for Astrophysics

Calibration of the ComPair Balloon Instrument

Nicholas Kirschner, Zachary Metzler, Lucas D. Smith et al. (+25 more)

ComPair, the prototype of the All-sky Medium Energy Gamma-ray Observatory (AMEGO) mission concept, is a combined Compton imager and pair production telescope. It consists of four subsystems: a double-sided silicon strip detector (DSSD) Tracker, a virtual Frisch-grid cadmium zinc telluride (CZT) Low Energy Calorimeter, a cesium iodide (CsI) High Energy Calorimeter, and a plastic scintillator Anti-Coincidence Detector (ACD) to reject the charged particle background. These subsystems work together to reconstruct events, by tracking the locations and energies of gamma-ray scatters and pair production events. To quantify ComPair's scientific capabilities prior to a balloon launch in 2023, calibrations were performed to benchmark the instrument's performance in terms of angular resolution, energy resolution, and effective area. In this paper we provide an overview of the ComPair instrument and detail the calibration campaign. Finally, we compare our results to the expected performance based on simulations.
Read the full abstract

All authors Nicholas Kirschner, Zachary Metzler, Lucas D. Smith, Carolyn Kierans, Regina Caputo, Nicholas Cannady, Makoto Sasaki, Daniel Shy, Priyarshini Ghosh, Sean Griffin, J. Eric Grove, Elizabeth Hays, Iker Liceaga-Indart, Emily Kong, Julie McEnery, John Mitchell, A. A. Moiseev, Lucas Parker, Jeremy S. Perkins, Bernard Phlips, Adam J. Schoenwald, Clio Sleator, Jacob Smith, Janeth Valverde, Sambid Wasti, Richard Woolf, Eric Wulf, Anna Zajczyk

High Energy Astrophysical Phenomena

Strategy for identifying Vera C. Rubin Observatory kilonova candidates for targeted gravitational-wave searches

Simon Stevenson, Anais Möller and Jade Powell

Since the observation of the binary neutron star merger GW170817 and the associated kilonova AT2017gfo, the next joint gravitational-wave/optical kilonova has been highly anticipated. Overlapping observations between the Vera C. Rubin Observatory and the international gravitational-wave detector network are expected soon. Wide-field survey facilities, such as Rubin, can serve dual roles in gravitational-wave astronomy: conducting dedicated optical counterpart searches following gravitational-wave triggers and, through surveys such as the Legacy Survey of Space and Time (LSST), providing opportunities for fortuitous kilonova discoveries during routine operations. We use simulations to develop a strategy for identifying kilonova candidates observed by Rubin and processed by the Fink broker. These candidates can be used as astrophysical triggers for a targeted gravitational-wave search. We simulate kilonovae light-curves for the first year of Rubin with the latest observing strategy for the Wide-Fast-Deep and the Deep Drilling Fields. Assuming a kilonova rate of 250 Gpc$^{-3}$ yr$^{-1}$, we find that Rubin brokers should observe $\sim 4$ kilonovae per year with at least one alert above a signal-to-noise ratio of 5 within the gravitational-wave detector horizon ($\sim 350$ Mpc). Most of these will be faint, and detected 1-2 days following the neutron star merger. Photometric and spectroscopic follow-up will be limited to large telescopes. Using archival data from the Zwicky Transient Facility (ZTF) and our proposed selection criteria, we estimate a minimum contamination of at least 30 events per month from other transients and variables, even under our strictest selection criteria. A deep gravitational-wave search targeting Rubin kilonova candidates may lead to the next multi-messenger discovery.
Read the full abstract

Instrumentation and Methods for Astrophysics

InferA: A Smart Assistant for Cosmological Ensemble Data

Justin Z. Tam, Pascal Grosset, Divya Banesh et al. (+3 more)

Analyzing large-scale scientific datasets presents substantial challenges due to their sheer volume, structural complexity, and the need for specialized domain knowledge. Automation tools, such as PandasAI, typically require full data ingestion and lack context of the full data structure, making them impractical as intelligent data analysis assistants for datasets at the terabyte scale. To overcome these limitations, we propose InferA, a multi-agent system that leverages large language models to enable scalable and efficient scientific data analysis. At the core of the architecture is a supervisor agent that orchestrates a team of specialized agents responsible for distinct phases of the data retrieval and analysis. The system engages interactively with users to elicit their analytical intent and confirm query objectives, ensuring alignment between user goals and system actions. To demonstrate the framework's usability, we evaluate the system using ensemble runs from the HACC cosmology simulation which comprises several terabytes.
Read the full abstract

All authors Justin Z. Tam, Pascal Grosset, Divya Banesh, Nesar Ramachandra, Terece L. Turton, James Ahrens

Earth and Planetary Astrophysics

Towards High-Resolution Orbitrap Mass Spectrometry for Next- Generation In-Situ Space Dust Analysis

M. Malečková, I. Zymak, A. Spesyvyi et al. (+7 more)

Cosmic and planetary dust hold vital clues to the chemical evolution of the solar system, yet in situ analysis of their molecular and elemental composition remains technically challenging. Here we present laboratory results from HANKA (High-resolution mass Analyzer for Nano-scale Kinetic Astro materials), a compact Orbitrap-based mass spectrometer developed towards the goal of a universal dust detector for space applications. Using infrared laser ablation and plasma formation under vacuum, we analyzed solid-state samples representative of Lunar, Martian, and Meteoritic material. The resulting mass spectra - recorded at resolving powers of R=60000 - reveal complex, but characteristic element mixtures. These results demonstrate the single event sensitivity of HANKA, and its mass resolution with the ability to resolve complex mass spectra and possibly differentiate geochemical signatures across planetary bodies. The dynamic range of 3-4 orders of magnitude enables even the detection of trace compounds. The minimalistic impact sampling approach enables fast, high-precision compositional mass analysis without complex sample preparation, making the instrument well-suited for orbital, surface, or flyby missions with expected dust impacts. Our system consists of an IR-laser system that simulates impacts of nano to micron sized solid-state dust and ice particles from space. It therefore allows to perform so called analogue experiments in the laboratory. We conclude that IR- laser pulses on a solid-state material are not only well suited for ice particle impact analogues but also a good analogue experiment for solid state particle impacts on a dust detector electrode in space. Moreover, the IR laser is employed only for an optimal analogue experiment simulating the impact event - it is not necessary in space on a spacecraft detecting space dust.
Read the full abstract

All authors M. Malečková, I. Zymak, A. Spesyvyi, M. Polášek, B. Cherville, M. Lacko, M. Ferus, A. Charvat, J. Žabka, B. Abel

High Energy Astrophysical Phenomena

Mean Motion Resonances in AGN Disks

Marguerite Epstein-Martin, Nicholas Stone and Juliette Becker

Mean motion resonances (MMRs) are a generic outcome of convergent migration for bodies embedded in accretion disks around a central mass. Long studied in planetary systems, the same phenomenon should occur for stellar-mass black holes (BHs) in AGN disks. In this work, we derive simple analytic criteria describing when BH pairs are driven out of resonance, and use them to chart MMR stability across AGN parameter space, accounting for disruption from general-relativistic apsidal precession, hydrodynamic turbulence, and stellar stirring. Across plausible AGN disk models, we find three MBH mass regimes: (i) for $M/ M_\odot\gtrsim 10^{7.5}$, first order resonances are generically unstable; (ii) for $M/ M_\odot\lesssim 10^{6.5}$, stable MMRs are always present; (iii) for $10^{6.5}\lesssim M / M_\odot \lesssim 10^{7.5}$, stability depends on disk mass flux, the summed mass of the orbiters, and the nuclear-cusp slope. When present, stable MMRs commonly occur between an inner anti-trap and an outer trap set by thermal torque, a region where embedded objects migrate outward in the disk. These results imply that high-mass AGN allow convergent migration to proceed to LVK-band mergers largely without resonant chains, whereas low/intermediate-mass AGN can host MMRs, with the potential to reshape merger pathways.
Read the full abstract

Astrophysics of Galaxies

ALMAGAL VII. Cataloging Hierarchical Mass Structure from Cores to Clumps across the Galactic Disk

Jennifer Wallace, Taevis Kolz, Cara Battersby et al. (+42 more)

Investigating the multi-scale fragmentation of dense clumps into compact cores is essential for understanding the processes that govern the initial distribution of mass in stellar clusters and how high-mass stars ($>8~M_{\odot}$) form. We present a catalog of the hierarchical continuum structure from 904 clumps observed in the ALMAGAL program, a high resolution ($0.15-0.8$\arcsec) 1.38 mm Atacama Large Millimeter/submillimeter Array (ALMA) large program targeting dense clumps capable of high-mass star formation throughout the Galactic disk. We use \verb|astrodendro|, a dendrogram-based algorithm, on a uniform linear resolution (2000 au) version of the data to extract 5160 continuum structures with effective radii spanning $800-42000$ au and estimated masses between $~0.05-670~M_{\odot}$. With our large sample, we statistically examine differences in clump properties for regions with varying levels of hierarchical complexity. We find that clumps exhibiting the richest hierarchical morphology have distributions with higher dust temperatures, surface densities, luminosity-to-mass (L/M) ratios, and most massive core (MMC) masses, indicating that these regions tend to be at later evolutionary stages. We find a positive correlation between the mass of cores from the ALMAGAL core catalog and the surface density of their surrounding structures identified in this work. However, this correlation is weaker for cores in more evolved clumps, where lower mass cores can be found at higher local surface densities. This could indicate that some cores accrete mass less efficiently from the intra-clump reservoir than others, despite the total available mass increasing over time, a scenario that is congruent with a clump-fed core accretion model.
Read the full abstract

All authors Jennifer Wallace, Taevis Kolz, Cara Battersby, Aleksandra Kuznetsova, Álvaro Sánchez-Monge, Eugenio Schisano, Alessandro Coletta, Qizhou Zhang, Sergio Molinari, Peter Schilke, Paul T. P. Ho, Rolf Kuiper, Tianwei Zhang, Thomas Möller, Ralf S. Klessen, Maria T. Beltrán, Floris van der Tak, Stefania Pezzuto, Henrik Beuther, Alessio Traficante, Davide Elia, Leonardo Bronfman, Pamela Klaassen, Dariusz C. Lis, Luca Moscadelli, Kazi Rygl, Milena Benedettini, Chi Yan Law, Jofre Allande, Alice Nucara, Patrick M. Koch, Won-ju Kim, Patricio Sanhueza, Gary Fuller, Georgie Stroud, Beth Jones, Crystal Brogan, Todd Hunter, Aida Ahmadi, Adam Avison, Katharine Johnston, Sheng-Yuan Liu, Chiara Mininni, Yu-Nung Su, Hans Zinnecker

Cosmology and Nongalactic Astrophysics · Cross-listed from hep-ph

Gravity and the Hierarchy Problem

Thede de Boer, Jisuke Kubo, Manfred Lindner et al. (+1 more)

We propose a mechanism where the dynamical generation of the Planck mass in scale invariant gravity leads to Einstein gravity, successful inflation and an explanation of the hierarchy problem of the Standard Model. We will discuss the scale generation by dynamical symmetry breaking and phenomenological consequences.
Read the full abstract

All authors Thede de Boer, Jisuke Kubo, Manfred Lindner, Markus Reinig

Cosmology and Nongalactic Astrophysics

Revealing evolution of Dark Energy density from observations

José Blanco, Víctor H. Cárdenas and Cuauhtémoc Campuzano

We present a model–independent reconstruction of the normalized dark energy density function, $X(z) \equiv \rho_{\mathrm{de}}(z)/\rho_{\mathrm{de}}(0)$, derived directly from the DES-SN5YR Type~Ia supernova sample. The analysis employs an inversion formalism that relates the derivative of the distance modulus, $\mu^{\prime}(z)$, to the expansion history, allowing the data to determine the shape of $X(z)$ without assuming a specific equation–of–state or dark energy density parameterization. A statistically optimized binning of the supernova sample (using 17 intervals following the Freedman–Diaconis criterion and 34 following Scott's rule) ensures a stable estimation of $\mu^{\prime}(z)$ and a controlled propagation of uncertainties throughout the inversion process. The resulting $X(z)$ remains statistically consistent with a constant value within one standard deviation across the entire redshift range, showing no significant evidence for an evolving dark energy component at present. In a direct comparison among $\Lambda$CDM, CPL, and the quadratic $X^2(z)$ parameterization – where CPL and $X^2(z)$ each introduce two additional free parameters relative to $\Lambda$CDM – the CPL model attains the best statistical agreement with the data, albeit only marginally and strictly within this restricted model set. These outcomes indicate that current observations are compatible with an almost constant dark energy density ($w \simeq -1$), while the inversion framework remains sensitive to subtle departures that forthcoming high–precision surveys could resolve.
Read the full abstract

Cosmology and Nongalactic Astrophysics · Cross-listed from hep-ph

Dark Matter-Electron Interactions Alter the Luminosity and Spectral Index of M87

Abdelaziz Hussein and Gonzalo Herrera

We investigate the possibility that cosmic-ray electron cooling through dark matter-electron scatterings contributes to the low radiative efficiency observed in radio-loud galaxies such as M87. Light dark matter can scatter efficiently off electrons in M87, lowering the observed bolometric luminosity compared to astrophysical expectations. This consideration allows us to probe previously unexplored regions of the parameter space of dark matter-electron interactions. We further model the cosmic-ray electron distribution by numerically solving a diffusion equation along the jet and find that efficient dark matter-electron interactions can induce a flattening of the spectral index at different distances from the central supermassive black hole, in better alignment with radio observations from M87.
Read the full abstract

High Energy Astrophysical Phenomena · Cross-listed from hep-ph

New Spallation Background Rejection Techniques to Greatly Improve the Solar Neutrino Sensitivity of JUNO

Obada Nairat, John F. Beacom and Shirley Weishi Li

While the potential of the Jiangmen Underground Neutrino Observatory (JUNO) to measure solar neutrinos is known, realizing this potential requires new techniques to reduce detector backgrounds. One of the most serious backgrounds is due to the beta decays of unstable nuclei produced through muon breakup (spallation) of nuclei. This background is much more significant in JUNO compared to Super-Kamiokande due to JUNO's shallower depth and its lack of directional information. We present the first detailed theoretical calculations of spallation backgrounds in JUNO, showing the underlying physical processes and new ways to cut backgrounds while preserving signals. A key point is showing the importance of neutron tagging to identify hadronic showers, which are rare but produce almost all of the dangerous isotopes. With our new techniques, JUNO will be able to reduce deadtime (signal loss) by a factor of about 4.5 and to reduce the running time needed to meet sensitivity goals by a factor of two. This will give JUNO greatly improved sensitivity to $^8$B and $hep$ solar neutrinos, as we will explore in a separate paper.
Read the full abstract

Earth and Planetary Astrophysics

Eccentric Disks With Self-Gravity

Yoram Lithwick, Eugene Chiang, Leon Mikulinsky et al. (+1 more)

Can a disk orbiting a central body be eccentric, when the disk feels its own self-gravity and is pressureless? Contradictory answers appear in the literature. We show that such a disk can be eccentric, but only if it has a sharply truncated edge: the surface density $\Sigma$ must vanish at the edge, and the $\Sigma$ profile must be sufficiently steep at the point where it vanishes. If either requirement is violated, an eccentric disturbance leaks out of the bulk of the disk into the low density edge region, and cannot return. An edge where $\Sigma$ asymptotes to zero but never vanishes, as is often assumed for astrophysical disks, is insufficiently sharp. Similar results were shown by Hunter & Toomre (1969) for galactic warps. We demonstrate these results in three ways: by solving the eigenvalue equation for the eccentricity profile; by solving the initial value problem; and by analyzing a new and simple dispersion relation that is valid for any wavenumber, unlike WKB. As a byproduct, we show that softening the self-gravitational potential is not needed to model a flat disk, and we develop a softening-free algorithm to model the disk's Laplace-Lagrange-like equations. The algorithm is easy to implement and is more accurate than softening-based methods at a given resolution by many orders of magnitude.
Read the full abstract

All authors Yoram Lithwick, Eugene Chiang, Leon Mikulinsky, Zhenbang Yu

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

On the maximum compactness of neutron stars

Luciano Rezzolla and Christian Ecker

The stellar compactness, that is, the dimensionless ratio between the mass and radius of a compact star, $\mathcal{C} := M/R$, plays a fundamental role in characterising the gravitational and nuclear-physics aspects of neutron stars. Yet, because the compactness depends sensitively on the unknown equation of state (EOS) of nuclear matter, the simple question: “how compact can a neutron star be?” remains unanswered. To address this question, we adopt a statistical approach and consider a large number of parameterised EOSs that satisfy all known constraints from nuclear theory, perturbative Quantum Chromodynamics (QCD), and astrophysical observations. Next, we conjecture that, for any given EOS, the maximum compactness is attained by the star with the maximum mass of the sequence of nonrotating configurations. While we can prove this conjecture for a rather large class of solutions, its general proof is still lacking. However, the evidence from all of the EOSs considered strongly indicates that it is true in general. Exploiting the conjecture, we can concentrate on the compactness of the maximum-mass stars and show that an upper limit appears for the maximum compactness and is given by $\mathcal{C}_{\rm max} = 1/3$. Importantly, this upper limit is essentially independent of the stellar mass and a direct consequence of perturbative-QCD constraints.
Read the full abstract

High Energy Astrophysical Phenomena

Unified kinetic theory of induced scattering: Compton, Brillouin, and Raman processes in magnetized electron and positron pair plasma

Rei Nishiura, Shoma F. Kamijima and Kunihito Ioka

We extend a unified theoretical framework for induced (stimulated) scattering-parametric instabilities of electromagnetic waves, including induced Compton, stimulated Brillouin, and stimulated Raman scattering (SRS) in strongly magnetized electron-positron pair plasma. By solving the dispersion relations derived from kinetic theory, taking into account the ponderomotive force due to the beat of incident and scattered waves, we obtain analytical expressions for the linear growth rates of the ordinary, neutral, and charged modes of density fluctuations. Our results clarify which type of scattering dominates under different thermal coupling, resonance, and density conditions. In strong magnetic fields, scattering of perpendicularly polarized waves is generally suppressed, but by different powers of the cyclotron frequency. Moreover, SRS, which is forbidden in unmagnetized electron and positron pair plasma, becomes possible in the charged mode. This framework enables a comprehensive evaluation of induced scattering in extreme astrophysical and laboratory plasma, such as fast radio burst (FRB) emission and propagation in magnetar magnetospheres.
Read the full abstract

Cosmology and Nongalactic Astrophysics

Probabilistic Inference of Cosmological Density Parameters from Synthetic Hubble Expansion Data of Varying SNR Using Diverse Artificial Neural Network Architectures

Zijian Jin and Jaehyon Rhee

This paper builds upon ParamANN's novel approach (S. Pal & R. Saha 2024) of using ANNs to infer cosmological density parameters by determining optimal architecture for varying synthetic Hubble data SNRs in estimating the density parameters $\Omega_{m, 0}$ and $\Omega_{\Lambda, 0}$ across redshift values $z \in [0, 1]$. To generate the synthetic data, this study randomly sampled initial free parameter values at $z=0$ from theoretically motivated priors and evolved them backwards using the first Friedmann Equation to generate clean $H(z)$ curves. Then, this paper adds realistic noise of high, normal, and low SNR by sampling relative uncertainties from a Gaussian KDE on 47 real data observations compiled by A. Bouali et al. (2023). In the end, this study found that a RNN that uses BiLSTM is the most effective for high and normal SNR data across four quantitative metrics. On the other hand, a combination of convolution and recurrent layers that uses GRU performed the best for low SNR data across the same four metrics. A comparison between the results of this paper's ANN predictions and those of ParamANN shows that all architectures tested in this paper regardless of training SNR are statistically consistent within 1 standard deviation of ParamANN. However, most ANN results are not statistically consistent within 3 standard deviations of Planck Collaboration et al. (2020), showing a significant difference between ANN and the more traditional MCMC methods used by Planck collaboration.
Read the full abstract

Instrumentation and Methods for Astrophysics

Simulation of Time-dependent Karhunen-Loeve Phase Screens: an Ergodic Approach

Richard J. Mathar

Time-dependent phase screens in ground-based astronomy are typically simulated in the so-called frozen-screen approximation by establishing a static phase screen on a large pupil and dragging an aperture equivalent to the size of the actual input pupil across this oversized phase screen. The speed of this motion sweeping through the large phase screen is equivalent to a wind speed that changes the phase screen as a function of time. The ergodic ansatz replaces this concept by constructing the structure function in a three-dimensional volume – a sphere for reasons of computational efficiency – , sampling phase screens by two-dimensional planar cuts through that volume, and dragging them along the surface normal at some speed which generates a video of a phase screen. This manuscript addresses the linear algebra of populating the three-dimensional volume with phase screens of the von-Karman model of atmospheric turbulence.
Read the full abstract

Astrophysics of Galaxies

Spatial Variations of Polarized Synchrotron Emission in the QUIJOTE MFI Data using Neural Networks

J. M. Casas, L. Bonavera, J. González-Nuevo et al. (+7 more)

Polarized synchrotron emission from ultra-relativistic electrons spiraling the Galactic magnetic field has become one of the most relevant emissions in the Interstellar medium these last years due to the improvement in the quality of low-frequency observations. One of the recent experiments designed to explore this emission is the QUIJOTE experiment. We aim to study the spatial variations of the synchrotron emission in the QUIJOTE MFI data, by dividing the sky into physically separated regions. For such task, we firstly use a novel component separation method based on artificial neural networks to clean the synchrotron maps. After training the network with simulations, we fit both $EE$ and $BB$ spectra by assuming a power-law model. Then, we give estimations for the index $\alpha_{S}$, the amplitude, and the ratio between $B$ and $E$ amplitudes. When analyzing the real data, we found a clear spatial variation of the synchrotron properties along the sky at 11 GHz, obtaining a steeper index in the Galactic plane of $\alpha_{S}^{EE} = -3.1 \pm 0.3$ and $\alpha_{S}^{BB} = -3.10 \pm 0.28$ and a flatter one at high Galactic latitudes of $\alpha_{S}^{EE} = -3.05 \pm 0.16$ and $\alpha_{S}^{B} = -2.98 \pm 0.23$. We found average values at all sky of $\alpha_{S}^{EE} = -3.04 \pm 0.18$ and $\alpha_{S}^{BB} = -3.00 \pm 0.26$. Furthermore, after obtaining an average value of $A_{S}^{EE} = 3.31 \pm 0.17$ $\mu K^{2}$ and $A_{S}^{BB} = 0.93 \pm 0.04$ $\mu K^{2}$, we estimate a ratio between $B$ and $E$ amplitudes of $A_{S}^{BB}/A_{S}^{EE} = 0.28 \pm 0.06$. Based on the results we conclude that, although neural networks seem to be valuable methods to apply on real ISM observations, combined analyses with Planck, WMAP and/or CBASS data are mandatory to reduce the contamination from QUIJOTE maps and then improve the accuracy of the estimations.
Read the full abstract

All authors J. M. Casas, L. Bonavera, J. González-Nuevo, J. A. Rubiño-Martín, R. T. Génova-Santos, R. B. Barreiro, M. M. Cueli, D. Crespo, R. Fernández-Fernández, J. A. Cano

Instrumentation and Methods for Astrophysics

Diffusion models for polarimetric reconstruction of circumstellar environments

Quentin Villegas, Laurence Denneulin, Simon Prunet et al. (+5 more)

In this paper, we propose an approach combining diffusion models and inverse problems for the reconstruction of circumstellar disk images. Our method builds upon the Rhapsodie framework for polarimetric imaging, substituting its classical prior with a diffusion model trained on synthetic data. Our formulation explicitly incorporates stellar leakage while efficiently handling missing data and high level noise inherent to high-contrast polarimetric imaging. Experiments show significant improvement over conventional methods within our framework of assumptions, opening new perspectives for studying circumstellar environments.
Read the full abstract

All authors Quentin Villegas, Laurence Denneulin, Simon Prunet, André Ferrari, Nelly Pustelnik, Éric Thiébaut, Julian Tachella, Maud Langlois