Solar and Stellar Astrophysics
Towards a Fully Automated Pipeline for Short-Term Forecasting of In Situ Coronal Mass Ejection Magnetic Field Structure
Hannah T. Rüdisser, Emma E. Davies, Ute V. Amerstorfer et al. (+6 more)
We present an automated pipeline for operational short-term
forecasting of coronal mass ejection (CME)
magnetic field structure at L1, coupling arrival time prediction, in situ detection, and iterative flux rope reconstruction, following near-real-time remote-sensing CME identification. The system is triggered by new entries in the CCMC DONKI database and first applies the drag-based ELEvo model to determine whether an Earth impact is expected and estimate arrival time. This estimate defines a temporal window constraining the search for CME signatures in real-time L1 in situ
solar wind data, where the
magnetic obstacle (MO) is automatically detected using the deep learning model ARCANE. Upon MO onset, iterative reconstructions with the semi-empirical flux rope model 3DCORE are performed, using a Monte Carlo fitting scheme, producing continuously updated forecasts of the remaining
magnetic field profile. We evaluate the pipeline using 3870 archived DONKI entries and archived NOAA real-time in situ data from 2013-2025, assessing forecast performance at different stages of MO observation. For 61 events with an associated ground-truth counterpart in the ICMECAT catalog, forecasts based on initial MO data already achieve performance comparable to full-event reconstructions. Typical errors are ~5 hours in timing of
magnetic field extrema and ~10 nT in field strength metrics, with limited systematic improvement as more of the event is observed. Results show substantial event variability and systematic underestimation of extrema, indicating deviations from ideal flux rope assumptions. These findings demonstrate the potential of fully autonomous real-time
forecasting while highlighting limitations imposed by event complexity and model representational capacity.
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All authors Hannah T. Rüdisser, Emma E. Davies, Ute V. Amerstorfer, Christian Möstl, Eva Weiler, Andreas J. Weiss, Justin Le Louëdec, Martin A. Reiss, Gautier Nguyen
Cosmology and Nongalactic Astrophysics · Cross-listed from hep-ph
Parametric-Resonance Production of QCD Axions
Pirzada, Yu Gao and Qiaoli Yang
Dark matter
axion production can be significantly enhanced through a generic cosmological mechanism:
primordial temperature fluctuations periodically modulate the
axion mass during the QCD phase transition, thereby triggering parametric resonance in
axion field
evolution. This interplay between the resonance and the misalignment mechanism moves the predicted
axion mass window for the observed dark matter abundance to $10^{-4}-10^{-3} \, \text{eV}$, shifting the preferred mass to previously unexplored higher ranges.
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High Energy Astrophysical Phenomena
Optical spectral characterization of OP 313. Constraining the contribution of thermal and non-thermal optical emission
J. Otero-Santos, M. Nievas Rosillo, J. A. Acosta-Pulido et al. (+1 more)
The
quasar OP 313 was discovered in December 2023 in very-high-energy $\gamma$ rays above 100 GeV, enabling for the first time a complete characterization of its emission. However, the lack of updated measurements of its
accretion disk, broad line region and dusty
torus hampers a detailed interpretation of the role of
accretion in the observed $\gamma$-ray production. We intend to characterize, during high-activity states, the external
photon fields contributing to the IR-to-UV emission$-$namely dusty
torus, broad line region and
accretion disk$-$and investigate potential variability and blurring effects on the broad emission lines. We present new spectroscopic observations of OP 313 with the NOT and TNG
telescopes to characterize its optical spectrum and variability with respect to archival observations from SDSS. We measure the luminosity of different broad emission lines, characterizing the broad line region,
accretion disk and dusty
torus. We measure the Mg II emission line, with an average flux of $F_{\mathrm{Mg \ II}} = (0.85 \pm 0.11)\times 10^{-14}$ erg cm$^{-2}$ s$^{-1}$. Its equivalent width and luminosity are consistent with a constant line with a variable non-thermal continuum. From the stable Mg II line we derive a constant luminosity of the thermal components, $\log(L_{\mathrm{BLR}} \ \mathrm{[erg \ s^{-1}]}) = 44.91 \pm 0.19$, $\log(L_{\mathrm{disk}} \ \mathrm{[erg \ s^{-1}]}) = 45.91 \pm 0.19$ and $\log(L_{\mathrm{torus}} \ \mathrm{[erg \ s^{-1}]}) = 44.70 \pm 0.16$, and estimated a BH mass of $\log(M_{BH}/M_{\odot})=8.36 \pm 0.18$, in line with with that derived from the C III] line. These characteristics and the indicator of the
accretion rate from the disk/Eddington luminosity ratio $\lambda =L_{AD}/L_{Edd} = 0.23 \pm 0.10$, along with a high Compton dominance, favour a FSRQ-like nature, contrary to the argued changing-look nature.
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All authors J. Otero-Santos, M. Nievas Rosillo, J. A. Acosta-Pulido, R. Clavero
Cosmology and Nongalactic Astrophysics
Non-spherical BUFFALOs: a weak lensing view of the Frontier Field clusters and associated systematics
A. Niemiec, A. Acebron, B. Beauchesne et al. (+15 more)
Galaxy clusters are tracers of the large scale structures of the Universe, making the time
evolution of their mass function dependent on key cosmological parameters, such as the
cosmic matter density or the amplitude of density fluctuations $\sigma_8$. Accurate measurements of cluster's total masses are therefore essential, yet they can be challenging, particularly for clusters with complex morphologies, as simple mass profiles are often adopted to fit the measurements. In this work, we focus on the Frontier Fields
galaxy clusters: a sample of six extremely massive systems, that, in most cases, exhibit highly complex mass distributions. The BUFFALO survey extended the Hubble Space
Telescope observations for the Frontier Fields
galaxy clusters, providing high-resolution multi-band imaging within a few Mpc. Combining this high-quality imaging
dataset with ancillary spectroscopy, we produce weak-
lensing catalogues with very high source densities, about 50 sources/arcmin$^2$. This allows us to robustly estimate the individual weak-
lensing cluster masses and quantify the sensitivity of these measurements on different factors, such as the cluster centring, the uncertainty on the
redshift distribution or the foreground contamination and boost factor correction. This provides a data-driven analysis of the different sources of systematics that can impact such measurements. We find that the largest sources of systematic bias arise for the most disturbed clusters, such as the multi-modal, merging
galaxy cluster Abell 2744. This analysis sets a comprehensive framework for assessing the impact of systematics on the weak-
lensing estimates of cluster masses, and in particular, in the case of unrelaxed clusters. This can play a key role in forthcoming cosmological analyses based on wide-field surveys such as Euclid and the Legacy Survey of Space and Time of the Rubin Observatory.
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All authors A. Niemiec, A. Acebron, B. Beauchesne, M. Jauzac, J. M. Diego, D. Eckert, D. Harvey, A. M. Koekemoer, D. J. Lagattuta, M. Limousin, G. Mahler, N. Patel, S. Tam, J. F. V. Allingham, R. Cen, A. Faisst, D. Perera, M. Sereno
Earth and Planetary Astrophysics
Astrometric follow-up of near-Earth asteroid 2024 YR4 during a Torino scale level 3 alert
Marco Micheli, Maxime Devogèle, Larry Denneau et al. (+38 more)
The discovery of 2024 YR4 presented the planetary defense community with the most significant impact threat in almost two decades, reaching level 3 on the Torino scale. The community, now mature and well-organized, responded with a global observational effort. Astrometric measurements, forming the basis for orbital refinement and impact prediction, were a central component of this response. In this paper, we present the astrometric data collected by the international community, from the time of discovery until the object became too faint for all existing observational assets, including JWST. We also discuss the coordination role played by the International Asteroid Warning Network, and the importance of publicly available image archives to enable precovery searches.
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All authors Marco Micheli, Maxime Devogèle, Larry Denneau, Eileen V. Ryan, William H. Ryan, Petr Pravec, Kamil Hornoch, Hana Kučáková, Petr Fatka, Melissa J. Brucker, Cassandra Lejoly, Nicholas Moskovitz, Mikael Granvik, Zuri Gray, Grigori Fedorets, Anlaug Amanda Djupvik, Carson Fuls, David Rankin, Kacper Wierzchoś, Bill Gray, Tim Lister, Richard J. Wainscoat, Robert Weryk, Olivier R. Hainaut, Federica Spoto, Peter Veres, Andrew S. Rivkin, Bryan J. Holler, Artem Y. Burdanov, Julien de Wit, Davide Farnocchia, Regina Rudawska, Eduardo Alonso Peleato, Francisco Ocaña, John Tonry, Jeroen Audenaert, Laura Faggioli, Francesco Gianotto, Marco Fenucci, Luca Conversi, Richard Moissl
Solar and Stellar Astrophysics
Magnetohydrodynamic instabilities in stellar radiative regions. I. Linear study of shear-driven instabilities
V. Durepaire, L. Petitdemange, K. Belkacem et al. (+4 more)
This paper is the first in a series investigating magnetohydrodynamic instabilities that may contribute to angular-momentum transport and
magnetic-field
evolution in
stellar radiative zones. We focus on shear-driven instabilities, specifically the Goldreich-Schubert-Fricke (GSF) instability and the magnetorotational instability (MRI), which are expected to play key roles in the internal dynamics of radiative regions. We carried out a local linear stability analysis using a numerical approach that extends beyond classical limiting cases and includes stabilizing effects such as stratification and
magnetic tension, allowing the exploration of realistic flow regimes. These results were validated through a global mode analysis in a Taylor-Couette configuration. We recovered the standard MRI and azimuthal MRI stability criteria and quantified the effects of stratification,
magnetic tension, and
diffusion on their growth. In strongly sheared regimes, we derived a new criterion for the magnetised GSF (MGSF) instability and clarified the transition from SMRI to MGSF as stratification and
magnetic effects narrow the unstable domain. We also provided approximate growth-time formulae that identify the dominant instability under given
stellar conditions and can be implemented in 1D
stellar evolution codes. Global Taylor-Couette calculations validate the local WKB analysis. Applied to subgiants and young red
giants, our results show that shear-driven instabilities can grow rapidly for
magnetic fields below 100 kG. Strong axial fields (100 kG) confined to the hydrogen-burning shell suppress instabilities unless the shear is sufficiently distant. These results support incorporating our criteria and growth estimates into
stellar evolution models to assess the efficiency of shear-driven transport.
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All authors V. Durepaire, L. Petitdemange, K. Belkacem, A. Guseva, L. Manchon, R. Hollerbach, F. Daniel
Instrumentation and Methods for Astrophysics
Antenna for the detection of electromagnetic audio-band disturbances on-board LISA
D. Serrano, A. Pérez-Ortega, D. Roma-Dollase et al. (+4 more)
The LISA mission will be the first observatory to detect gravitational waves from space within the millihertz frequency band.
Magnetic forces have an important impact on the instrument's sensitivity below the millihertz. Hence, monitoring the
magnetic environment within each of the LISA spacecrafts is of utmost importance. In this Letter we present the characterization of the coils that were used in LISA Pathfinder (LPF) when operating as
magnetic sensors in the audio frequency band. The necessity of implementing this type of magnetometer is presented in order to monitor high frequency
magnetic signals from the electronics on-board. We show that the LPF coils have a performance one order of magnitude better than the current requirements set by the LISA mission at the low end of the audio-band frequency. The LPF coils are able to measure a
magnetic noise level of 1.45 $\rm pT/\sqrt{\rm{Hz}}$ at 50 Hz and 0.17 $\rm pT/\sqrt{\rm{Hz}}$ at 500 Hz. Additionally, the LPF coils can reach a
magnetic noise floor of 0.1 $\rm pT/\sqrt{\rm{Hz}}$ at frequencies above 1 kHz.
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All authors D. Serrano, A. Pérez-Ortega, D. Roma-Dollase, J. Salvans-Tort, J. Ho-Zhang, J. Ramos-Castro, M. Nofrarias
Solar and Stellar Astrophysics
Asteroseismic ages for 17,000 stars in Kepler, K2 and TESS
Emma Willett, Andrea Miglio, Saniya Khan et al. (+9 more)
The availability of asteroseismic constraints for tens of thousands of red
giant (RG)
stars has opened the door to robust age estimates, enabling time-resolved studies of different populations of
stars in the Milky Way. This study leverages data from Kepler, K2, and TESS, in conjunction with astrometric data from
Gaia DR3 and spectroscopic constraints from APOGEE DR17 and GALAH DR3, to infer parameters for over 17,000 RGs. We use the code PARAM to homogeneously infer
stellar properties considering in detail the sensitivity of our results to different choices of observational constraints. We focus on age estimation, identifying potentially unreliable age determinations, and highlight
stars with unreliable $\Delta\nu$ measurements based on comparisons using
Gaia luminosities. These are particularly relevant in K2 data due to the short duration of the observations of each campaign, and therefore important to characterise for
Galactic archaeology studies where the spatial range of K2 is a benefit. Thanks to the combination of data from different missions we explore trends in age, mass, and orbital parameters such as $R_\mathrm{g}$ and $Z_\mathrm{max}$, and examine time-resolved [$\alpha$/M]-[Fe/H] planes across different
Galactic regions. Additionally, we compare age distributions in low- and high-$\alpha$ populations and chemically selected ex situ
stars. The study also extends known mass-[C/N] ratio relationships to lower masses. The catalogues resulting from this work will be instrumental in addressing key questions in
Galactic archaeology and
stellar evolution, and to improve training sets for machine-learning-based age estimations.
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All authors Emma Willett, Andrea Miglio, Saniya Khan, Yvonne Elsworth, Benoît Mosser, Karsten Brogaard, Giada Casali, Cristina Chiappini, Valeria Grisoni, Amalie Stokholm, Diego Bossini, William J. Chaplin
High Energy Astrophysical Phenomena
Merger Driven or Internal Evolution? A New Morphological Study of Tidal Disruption Event Host Galaxies
Janet N.Y. Chang, Connor Bottrell, Lixin Dai et al. (+7 more)
The host
galaxies of
tidal disruption events (TDEs) show enhanced central
stellar concentration and are preferentially found in poststarburst and green valley populations. This connection has led to the proposal that TDE host
galaxies likely have gone through recent mergers. We conduct a new morphological study of 14 TDE host
galaxies, using the r-band images from the Sloan Digital Sky Survey (SDSS), Dark Energy Camera Legacy Survey, and Ultraviolet Near-Infrared Optical Northern Survey, with the images from the latter two surveys having much higher depth and resolution than SDSS. We examine
galaxy structures using conventional methods and also apply diagnostics of merger activity from a suite of machine learning models. Consistent with previous studies, our results show that TDE host
galaxies are ~16% more centrally concentrated when compared to non-TDE-host controls. However, surprisingly, TDE hosts lack any indication of significant recent merger activity from both morphological analysis and the machine learning merger classifier. Instead, our results reveal that TDE host
galaxies in the green valley are approximately 1.5-3 times more likely to have bar-like or ringlike structures compared to their controls. Based on these results, we propose that bar-driven secular
evolution, instead of mergers, likely dominates the recent
evolution of the TDE hosts found in the green valley, which can simultaneously explain their distinctive
nuclear properties and enhanced TDE rates.
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All authors Janet N.Y. Chang, Connor Bottrell, Lixin Dai, Rudrani Kar Chowdhury, Meng Gu, Renbin Yan, Leonardo Ferreira, Sara L. Ellison, Scott Wilkinson, Thomas de Boer
High Energy Astrophysical Phenomena · Cross-listed from nucl-th
Many-body effects on dense matter with hyperons at finite temperature
Rafael Bán Jacobsen, Ricardo Luciano Sonego Farias and Veronica Dexheimer
In this work, we present the first extension of the Many-Body Forces (MBF) Model to finite temperature. The MBF Model describes
nuclear matter in a relativistic
quantum hadrodynamics formalism that takes many-body forces into account through a field dependence of the
nuclear interaction coupling constants. Assuming
nuclear matter to be charge neutral, beta-equilibrated, and populated by the
baryon octet, electrons,
muons, and
neutrinos, we explore the parameter of the model that controls many-body forces, three different hyperon coupling schemes (also introduced here for the first time in the MBF Model), and temperature effects to describe basic properties of
nuclear matter, including the speed of sound, compressibility, and adiabatic index. We also investigate the mass-radius relation of
neutron and protoneutron
stars by solving the Tolman-Oppenheimer-Volkoff equations at zero and finite temperature, including scenarios with fixed
entropy per
baryon and
lepton fraction. We find that different hyperon coupling schemes soften the equation of state to different degrees, requiring different degrees of many-body force effects to reproduce observations, although they are never zero. Multidimensional tables with our results are available in the CompOSE repository, ready to be used in astrophysical simulations.
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Cosmology and Nongalactic Astrophysics
Primordial Black Hole Abundance from Reionization
Ziwen Yin, Hanyu Cheng and Luca Visinelli
We derive robust constraints on the initial abundance of evaporating
primordial black holes (PBHs) using the reionization history of the Universe as a cosmological probe. We focus on PBHs that inject electromagnetic (EM) energy into the intergalactic medium (IGM) after recombination, in the mass range $3.2\times 10^{13}\,\mathrm{g} \lesssim M_{\rm PBH} \lesssim 5\times 10^{14}\,\mathrm{g}$. For each PBH mass, we compute the
redshift-dependent energy injection from Hawking evaporation using BlackHawk, fully accounting for the time
evolution of the PBH mass and the complete spectrum of emitted Standard Model particles and gravitons. The resulting
photons and electrons are propagated through the
primordial plasma using DarkHistory, which self-consistently models EM cascades and determines the fraction of injected energy deposited into ionization, excitation, and heating of the IGM. These modifications to the ionization and thermal histories are incorporated into a Gaussian Process reconstruction of the free-electron fraction based on low-$\ell$ CMB polarization data from the Planck mission. This non-parametric approach allows for a statistically well-defined separation between exotic high-
redshift energy injection and late-time astrophysical reionization, allowing PBH evaporation to be constrained through its contribution to the high-
redshift optical depth. Requiring consistency with current CMB measurements, we obtain upper limits on the initial PBH abundance that are robust against reionization modeling uncertainties and systematically more conservative than existing bounds, reflecting the fully numerical and time-dependent treatment of Hawking evaporation and energy deposition. Our results demonstrate the power of reionization observables as a precision probe of PBH evaporation and other scenarios involving late-time energy injection.
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Astrophysics of Galaxies
The X-ray properties of the most luminous quasars with strong emission-line outflows
Anastasia Shlentsova, Bartolomeo Trefoloni, Matilde Signorini et al. (+7 more)
Strong
outflows from active
galactic nuclei are frequently observed in objects with lower coronal X-ray luminosity. This intrinsic X-ray weakness is considered a requirement for the formation of radiatively driven winds. To obtain an unbiased view on the connection between X-ray emission and the presence of powerful winds in the most luminous
quasar phase, we present an X-ray analysis of a sample of extremely luminous,
radio-quiet
quasars with signatures of strong
outflows in their rest-frame ultraviolet (UV) emission spectra. We study the $Chandra$ X-ray spectral properties of 10 objects, selected from the Sloan Digital Sky Survey Data Release 16
quasar catalogue based on their UV luminosities and ${\rm C}_{\rm IV}$ emission line blueshifts, comparing them to typical optically blue
quasars. Our analysis reveals that seven out of 10
quasars in our sample have
photon indices $\Gamma>1.7$. Only two out of 10 objects exhibiting
outflows with velocities exceeding 1400 km/s are X-ray 'weak', consistent with the fraction of X-ray 'weak' objects generally observed in
quasar populations. Notably, one of the objects identified as X-ray 'weak' is likely an intrinsically X-ray 'normal'
quasar that is heavily obscured. We observe a tentative indication at a $\sim$2$\sigma$ confidence level that the correlation between the excessively low X-ray flux level and the presence of ${\rm C}_{\rm IV}$ emission-line
outflows might emerge at wind velocities greater than 3000 km/s. Our study provides additional evidence that the relationship between X-ray emission and the presence of winds is intricate. Our findings emphasise the need for X-ray observations of a larger sample of UV-selected
quasars with confirmed strong emission-line
outflows to unravel the nuanced interplay between winds and X-ray emission.
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All authors Anastasia Shlentsova, Bartolomeo Trefoloni, Matilde Signorini, Guido Risaliti, Elisabeta Lusso, Emanuele Nardini, Franz E. Bauer, Matthew J. Temple, Amy L. Rankine, Gordon T. Richards
High Energy Astrophysical Phenomena
Forecasting Supermassive Black Hole Binary Gravitational Wave Probes: Prospects for Future Pulsar Timing Array and Space-Borne Detectors
Katsunori Kusakabe, Yoshiyuki Inoue, Daisuke Toyouchi et al. (+1 more)
We present a comprehensive framework for predicting the detection prospects of supermassive black hole binaries (SMBHBs) by future gravitational wave (GW) observatories, examining both space-borne detectors (LISA, Taiji, TianQin) and next-generation
pulsar timing array (PTA) combined with the Square Kilometre Array (SKA-PTA). Leveraging dual active
galactic nucleus (AGN) fractions and AGN X-ray luminosity functions, we systematically evaluate the detectable SMBHB populations with a detection threshold of signal-to-noise ratio $\geq 5$ for each GW observatory. Our analysis reveals that space-borne detectors are expected to identify approximately $\sim 1 \text{--} 2$ to $\sim 20$ events per year, depending on the SMBHB orbital
evolution prescriptions. On the other hand, SKA-PTA demonstrates the potential to reach the first GW detection from individual SMBHBs within a few years of observation and achieve detectable GW source counts of $10^2 \text{--} 10^3$ after about 10 years, depending on PTA configurations. These facilities will significantly improve SMBHB detectability and enable characterization of their properties across different frequency bands.
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All authors Katsunori Kusakabe, Yoshiyuki Inoue, Daisuke Toyouchi, Keitaro Takahashi
Astrophysics of Galaxies
Heavy interstellar scattering toward the near end of the Galactic bar
A. B. Pushkarev, A. Brunthaler, Y. Y. Kovalev et al. (+8 more)
We present results of a pilot observational wide-field VLBI campaign on probing scattering properties of the partly ionized interstellar medium towards the
Galactic plane sky region between $28^\circ<l<36^\circ$ and $|b|<1^\circ$. This covers the region where the
Galactic bar connects to the spiral arms and where a lot of
star formation is currently ongoing. The Very Long Baseline Array (VLBA) observations of the whole region were performed in a special mode with multiple phase centers at L-band (1.4 – 1.8 GHz) during April-June 2022 and a year later complemented by sessions at S (2.2 – 2.4 GHz) and C-band (4.6 – 5.0 GHz) partially covering the pilot region. We found compelling evidence that target sources are subject to scattering. The total detection rate in L, S and C-bands is 1.5, 3.4 and 9.2 per cent, respectively, and approximately scales with the square of the observation frequency. The low rate values imply that scattering is strong. Its power is non-uniform across the
Galactic plane and it can be approximated by a Gaussian with a width of about $2^\circ$ peaking at the
Galactic mid-plane. One of the brightest sources of the field shows anisotropic scattering, with a $\lambda^2$ dependence of its observed angular size, along a position angle of $26^\circ$ aligned with the line of constant
Galactic latitude. We estimate the
turbulence dissipation scale $r_\text{in}\approx1500$ km toward the source J1833+0015.
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All authors A. B. Pushkarev, A. Brunthaler, Y. Y. Kovalev, M. M. Lisakov, I. N. Pashchenko, A. V. Plavin, N. Roy, P. A. Voitsik, S. A. Dzib, T. A. Koryukova, A. Y. Yang
High Energy Astrophysical Phenomena
Sensipy: simulate gamma-ray observations of transient astrophysical sources
Jarred G. Green, Barbara Patricelli, Antonio Stamerra et al. (+1 more)
We present sensipy, an open-source Python toolkit for simulating observations of transient astrophysical sources, particularly in the high-energy (HE, keV-GeV) and very-high-energy (VHE, GeV-TeV) gamma-ray ranges. The most explosive events in our universe are often short-lived, emitting the bulk of their energy in a relatively narrow time window. Due to often rapidly fading emission profiles, understanding how and when to observe these sources is crucial both to test theoretical predictions and efficiently optimize available
telescope time. The information extracted from the tools included in sensipy can be used to help astronomers investigate the detectability of sources considering various theoretical assumptions about their emission processes and mechanisms. This information can further help to justify the feasibility of proposed observations, estimate detection rates (events/year) for various classes of sources, and provide scheduling insight in realtime during gamma-ray and multi-messenger observational campaigns.
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All authors Jarred G. Green, Barbara Patricelli, Antonio Stamerra, Monica Seglar-Arroyo
Solar and Stellar Astrophysics
Dilution of accreted planetary matter in hot DA white dwarfs according to their mass
M. Deal, S. Vauclair, S. Charpinet et al. (+1 more)
A large proportion of observed white
dwarfs (WDs) show evidence of debris disks, remnants of the former planetary systems, and/or signatures of heavy elements in their atmospheres, induced by the
accretion of planetary matter onto their surfaces. The observed abundances are the result of the balance between the
accretion flux and the dilution of this planetary material by internal transport processes. A recent study showed that more massive DA WDs are less polluted than smaller mass ones. It was suggested that the reason could be related to the formation of planetary systems when these
stars were on the main sequence. The aim of this work is to test how internal dilution processes, including thermohaline convection, change with WD masses, and whether such an effect could account for variations in the observed pollution. We computed the efficiency of atomic
diffusion and thermohaline convection after the
accretion of heavy elements onto WDs using static DA models with various masses, effective temperatures, and hydrogen contents. We confirm that thermohaline convection is always more efficient in diluting accreted elements than atomic
diffusion, as previously shown in the literature. However, we find that element dilution by thermohaline convection is less efficient in massive WDs than in smaller mass ones, due to their larger internal density. We showed that the differences in observed heavy element pollution in WDs according to their masses cannot be explained by the dilution induced by atomic
diffusion and thermohaline mixing alone. Indeed, the pollution by planetary system
accretion should be more easily detectable in massive WDs than in low-mass ones. We discuss other processes that should be taken into account before drawing any conclusion about the occurrences of planetary systems according to the mass of the
star on the main sequence.
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All authors M. Deal, S. Vauclair, S. Charpinet, G. Vauclair
Earth and Planetary Astrophysics · Cross-listed from cs.GR
Real time, cross platform visualizations with zero dependencies for the N-body package REBOUND
Hanno Rein
Visualizations have become an indispensable part of the scientific process. A vibrant ecosystem of visualization tools exists, catering to a wide variety of different needs. Real-time visualizations of numerical simulations offer scientists immediate feedback about the status of their simulations and can also be valuable educational and outreach tools. Developing a visualization tool with support for different operating systems, CPU/GPU architectures, and programming
languages can be a challenge. It is common to use one or more graphics or UI libraries to act as abstraction layers and hide the underlying complexity. Whereas external libraries greatly simplify the initial programming effort, we argue that relying on them introduces new dependencies and problems, such as a higher entry barriers for new developers and users, and uncertainty regarding long-term support. In this paper we present a new approach for real time visualizations which we have implemented for the N-body package REBOUND. We propose to use a web browser to handle GPU accelerated rendering. This enables us to offer 3D, interactive visualizations on all major operating systems. What makes our new approach unique is that we achieve this without the need for any external libraries. We utilize WebAssembly to reuse existing OpenGL visualization code. Using communication via HTTP and a custom built-in web server, we are able to provide both local and remote real time visualizations. In addition to the browser based real time visualization, our approach offers other additional operating modes, including simulations running entirely within the browser, visualizations within jupyter notebooks, and traditional standalone visualizations using OpenGL. We focus on the implementation in REBOUND but the concepts and ideas discussed can be applied to many other areas in need of scientific and non-scientific real time visualizations.
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Instrumentation and Methods for Astrophysics · Cross-listed from gr-qc
Accelerating TTL noise post-processing via combined coefficients and alternative TDI configuration
Xue Wang and Gang Wang
Tilt-to-length (TTL) noise induced by angular jitter of spacecraft and test masses can affect the sensitivity of space-based gravitational-wave detectors such as LISA, Taiji, and TianQin. Such angular jitter can be measured using the differential wavefront sensing technique, enabling the modeling and subtraction of TTL noise from the data. However, owing to the multiple degrees of freedom of the detector constellation, a linear TTL model requires at least 24 parameters, while a higher-fidelity quadratic model involves up to 60 coefficients, rendering parameter estimation computationally expensive. To accelerate parameter determination, we propose a modified parameter set obtained via a linear transformation of the original angular coupling coefficients, which effectively reduces correlations among TTL noise components. In addition, we perform parameter fitting using an alternative second-generation time-delay interferometry configuration, PD4L, rather than the fiducial Michelson configuration. These two improvements enhance the convergence speed of the fitting procedure by a factor of approximately 10 for the linear model and approximately 18 for the quadratic model. The proposed approach can therefore substantially improve the efficiency of TTL noise calibration in space-based gravitational-wave detectors.
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Earth and Planetary Astrophysics
The effect of JWST/NIRSpec data reduction on the retrieval of WASP-39b atmospheric properties
J. Roy-Perez, S. Pérez-Hoyos, N. Barrado-Izagirre et al. (+1 more)
The JWST provides
exoplanet transit observations with unprecedented spectral coverage, enabling detailed atmospheric characterisation. However, systematics introduced during data reduction can lead to small but significant uncertainties that propagate into atmospheric
retrievals, making it essential to assess their impact on inferred properties. We aim to quantify the impact of different JWST/NIRSpec PRISM data-reduction processes as well as the relevance of saturation on the retrieved atmospheric properties of WASP-39b. We also assess whether or not these biases are comparable to those introduced by assumptions made in atmospheric modelling, particularly in the treatment of aerosol extinction. We perform nested-sampling
Bayesian retrievals using MultiNest and forward models generated with the Planetary Spectrum Generator. Six independently reduced spectra are analysed, considering both the full wavelength range and versions excluding the saturated region. We further test the effect of including three different cloud-opacity parameterisations. Differences among JWST/NIRSpec data-reduction pipelines lead to substantial variations in retrieved atmospheric properties of WASP-39b, often exceeding one order of magnitude, comparable to uncertainties from modelling assumptions. Excluding the saturated region reduces inter-pipeline dispersion but increases parameter degeneracies. This highlights the need for robust and homogeneous calibration strategies. The results also confirm that JWST data possess the sensitivity required to probe aerosol spectral behaviour, although such constraints remain strongly dependent on the adopted data-reduction strategy.
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All authors J. Roy-Perez, S. Pérez-Hoyos, N. Barrado-Izagirre, H. Chen-Chen
Astrophysics of Galaxies
Galaxies caught in transition: the role of group environment in shaping the mass-size relation in the local Universe
Gissel P. Montaguth, Claudia Mendes de Oliveira, Ciria Lima-Dias et al. (+8 more)
The
stellar mass-size relation is a sensitive probe of how environment shapes
galaxy structure. We analyse this relation in the local Universe for
galaxies in compact groups (CGs), low-mass groups ($M_{\rm vir} \leq 10^{13}~M_{\odot}$), and high-mass groups, comparing them to field
galaxies using data from the Southern Photometric Local Universe Survey.
Galaxies are classified as early types (ETGs; $n \geq 2.5$, $(u-r)_0 \geq 2.3$), late types (LTGs; $n < 2.5$, $(u-r)_0 < 2.3$), transition
galaxies (TGs; $n < 2.5$, $(u-r)_0 \geq 2.3$), and others (OGs; $n \geq 2.5$, $(u-r)_0 < 2.3$). We find that ETGs and OGs show no significant environmental dependence: their mass-size slopes and intercepts are statistically consistent across CGs, groups, and the field. LTGs also follow similar relations in the field and in most groups, with only a modest tendency for LTGs in CGs to be smaller at fixed
stellar mass. By contrast, TGs display a clear environmental signal: in groups the slope steepens to $\alpha \sim 0.4$ (versus $\alpha \sim 0.2$ in the field) and their sizes are smaller than in the field, with non-overlapping 95% posterior intervals. These trends suggest that TGs in denser environments are more structurally evolved, likely owing to enhanced bulge prominence and fading of the outer disc, consistent with the Sérsic-index distributions, which show an excess of TGs with $n_r \gtrsim 1.5$ in groups and CGs. Our findings highlight TGs as an environmentally sensitive population, providing insight into the structural transformation of
galaxies in group environments.
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All authors Gissel P. Montaguth, Claudia Mendes de Oliveira, Ciria Lima-Dias, Antonela Monachesi, Sergio Torres-Flores, Eduardo Telles, Fábio R. Herpich, Yolanda Jiménez-Teja, Antonio Kanaan, Tiago Ribeiro, William Schoenell
High Energy Astrophysical Phenomena · Cross-listed from hep-ph
Spin Light of neutrino in polarized matter
Alexander Grigoriev and Alexei Ternov
The
Spin Light of
neutrino ($SL\nu$) is an electromagnetic radiation of the
neutrino magnetic moment emitted when
neutrino moves in external conditions (fields or matter). The effect can be of significance in the extremely dense matter of compact astrophysical objects such as
neutron stars (NS). If detected, this radiation could provide a fair opportunity to study the properties of
neutrinos and the medium through which they move, since the properties of the radiation depend on both. Motivated by the possibility of the
nuclear matter
spin-polarization, in this paper, we study the new properties to $SL\nu$ obtained under the influence of net matter polarization. We demonstrate that the polarization can enhance or completely suppress the radiation. Also, it introduces a characteristic asymmetry into the total radiation from the compact object, which could be an observable feature dependent on the matter polarization and the
magnetic field inside the
stellar (if the field is connected to the
stellar matter polarization). The research may have implications for the physics of NS and magnetars, bringing us closer to the possibility of studying their internal structure.
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High Energy Astrophysical Phenomena · Cross-listed from nucl-th
Bayesian Constraints on the Neutron Star Equation of State with a Smooth Hadron-Quark Crossover
Xavier Grundler and Bao-An Li
We perform a
Bayesian inference of the dense-matter equation of state (EOS) within a unified framework that incorporates hadronic matter,
quark matter, and a smooth
hadron-to-
quark crossover. The EOS is constrained using physical consistency conditions, gravitational wave data from GW170817, NICER mass versus radius measurements, and hypothetical future high-precision radius observations. In contrast to most previous studies that assume a sharp first-order phase transition or fix part of the EOS, we simultaneously infer hadronic,
quark, and crossover parameters within a single statistical framework. We find that current observations strongly constrain the density dependence of the
nuclear symmetry energy, particularly its slope and
curvature. In contrast, the highest density hadronic parameters and
quark-matter properties remain only weakly constrained. We further show that the trace anomaly exhibits a remarkably universal behavior across the accepted EOS ensemble and remains largely insensitive to current observational constraints. This indicates that the present data primarily probe the low to intermediate density EOS. At the same time, robust inference of
quark matter and genuinely high-density physics will require next-generation precision radius measurements or complementary observables.
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Cosmology and Nongalactic Astrophysics · Cross-listed from gr-qc
Gravastars on the brane with a timelike extra dimension
Shounak Ghosh, Rikpratik Sengupta and Kazuharu Bamba
We construct a gravastar configuration within the Shtanov-Sahni (SS) braneworld scenario, characterized by a timelike extra dimension and negative brane tension. Unlike classical black holes, which inevitably culminate in central
curvature singularities, our model demonstrates that the SS braneworld dynamics naturally regularize the interior geometry and prevent singularity formation. By solving the modified Einstein field equations induced on the brane, we obtain explicit interior, shell, and exterior solutions without invoking the idealized thin-shell approximation. The gravastar core is modeled as a Bose–Einstein condensate, while the intermediate shell consists of ultra-dense stiff matter. Bulk Weyl corrections induce anisotropic effective pressures on the brane, a feature that emerges intrinsically in this scenario and supports stability. We analyze the active gravitational mass, energy,
entropy, and proper thickness of the shell, and establish the junction conditions at the interfaces. Our analysis reveals that the SS gravastar exhibits suppressed or even negative effective mass, reflecting the repulsive nature of the interior condensate, and admits stable
equilibrium solutions consistent with energy conditions. This highlights the SS braneworld gravastar as a physically viable compact object and a compelling alternative to black holes. A key novelty of our construction is that the stabilizing pressure anisotropy and suppressed effective gravitational mass arise dynamically from higher-dimensional Weyl corrections, rather than being imposed through ad hoc matter sources or thin-shell idealizations. This provides the first fully analytic realization of a finite-thickness, stable gravastar in the Shtanov-Sahni braneworld, highlighting a genuinely
geometric mechanism for singularity avoidance in compact objects.
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Instrumentation and Methods for Astrophysics
Introducing a new generation Adaptive Optics simulation framework: from PASSATA to SPECULA
Fabio Rossi, Alfio Puglisi and Guido Agapito
Numerical end-to-end simulation in Adaptive Optics (AO) is a key tool in the development of complex systems, from the initial design to the commissioning phase. Based on our previous experience with PASSATA, we decided to develop a new AO simulation framework in Python
language, naming it SPECULA (short for: Scalable Parallel Execution of Computations Upscaling Large Adaptive optics simulations). Following an object-oriented approach, the physical entities are modeled as processing objects connected to each other to exchange data objects. A simulation is run by providing its description instead of writing and executing a specific script. The Python
language and its library flexibility allowed us to write one single code that can be run on CPU and GPU platforms. We put a strong focus on computational efficiency, relying on CuPy and its interface to access the CUDA-stream mechanism. Moreover, SPECULA is capable of distributed computations over multiple processing nodes, making it suitable to run in an HPC environment, as tested on the Italian supercomputer Leonardo. SPECULA can also be used in laboratory environment to implement a hybrid simulation, allowing us to interface simulated and concrete objects: this feature was demonstrated in the Adaptive Optics laboratories at Arcetri Observatory. In this paper, we describe the main characteristics of SPECULA, show some relevant examples of its use, and finally draw our goals for the future.
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High Energy Astrophysical Phenomena · Cross-listed from hep-ph
Chiral phase transition with primordial black holes: Distinct phase structure and catalysis
Masanori Tanaka, Jun-Chen Wang and Jing-Jun Zhang
We study the impact of
primordial black holes (PBHs) on the
chiral phase transition and its associated
stochastic gravitational-wave (GW) signals. Using the three-
flavor Nambu-Jona-Lasinio model, we construct the
chiral effective potential in a Schwarzschild spacetime background. We find that PBHs promote
chiral symmetry restoration and induce a nontrivial local phase structure in the vicinity of the event horizon simultaneously. In particular, this structure exhibits a novel
chiral symmetry breaking pattern involving both second- and first-order phase transitions, a feature absent in flat spacetime. We further demonstrate that PBHs act as genuine catalysts for the
chiral phase transition by analyzing the bounce solution in curved spacetime. The presence of PBHs substantially enhances the inverse duration parameter $\beta/H$ while leaving the overall transition strength comparable to that in flat spacetime. As a consequence, even a small population of PBHs can induce $\mathcal{O}(1)$ shifts in both the peak frequency and the peak amplitude of the GW spectrum generated by the first-order dark
chiral phase transition.
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High Energy Astrophysical Phenomena
Rotational Behaviour of Exotic Compact Objects
Zakary Buras-Stubbs and Ilídio Lopes
We construct exotic compact objects composed entirely of self-interacting asymmetric fermionic dark matter governed by a repulsive Yukawa potential with massive dark interaction
boson. By considering the structural,
tidal, and rotational properties of
solar mass self-gravitating dark matter systems, and contrasting them against purely baryonic
neutron stars, described by the well understood SLy4 equation of state, we hope to shed some light on the place of dark compact systems in the context of gravitational wave astronomy, specifically due to the difficulty parsing mass and radius data from events with no electromagnetic counterpart. Here we consider systems composed of 1 GeV and 10 GeV dark matter. Relevant compact objects are then analysed and simulated as both static bodies, and rotating systems governed by the Hartle-Thorne formalism to second order. Here within we highlight the differences in key
tidal and rotational properties encoded in gravitational wave signals, and analyse how dark objects may mimic or distinguish themselves to current and future gravitational wave observatories.
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High Energy Astrophysical Phenomena
Studies on the spin and magnetic inclination evolution of magnetars Swift J1834.9-0846 under wind braking
Biaopeng Li, Zhifu Gao, Wenqi Ma et al. (+3 more)
The magnetar Swift J1834.9-0846 presents a significant challenge to
neutron star spin-down models. It exhibits two key anomalies: an insufficient rotational energy loss rate to power its observed X-ray luminosity, and a braking index of $ = 1.08\pm 0.04$, which starkly contradicts the canonical
magnetic dipole value of $n=3$. To explain these anomalies, we develop a unified
spin-
evolution model that self-consistently integrates
magnetic dipole radiation, gravitational wave emission, and wind braking. Within this framework, we constrain the wind braking parameter to $\kappa \in [13, 37]$ from the nebular properties, finding it contributes substantially (17%-51%) to the current
spin-down torque.
Bayesian inference reveals that the birth period is poorly constrained by present data and is prior-dependent, indicating a millisecond birth is allowed but not required. Furthermore, we constrain the number of precession cycles to $\xi \sim 10^{4}$–$10^{5}$, and our analysis favors a toroidally-dominated internal
magnetic field configuration as the most self-consistent explanation for the low braking index. Finally, we assess the continuous gravitational-wave detectability. The present-day signal is undetectable. However, the early-time signal might have reached the projected sensitivity of next-generation gravitational-wave observatories, such as the Advanced
Laser Interferometer Gravitational-Wave Observatory (aLIGO) and the Einstein
Telescope (ET), although a confident detection would require exceptionally stable rotation, an assumption considered highly optimistic for a young magnetar. This work establishes a unified framework that links magnetar
spin-down with their interior physics and multi-messenger observables, providing a physically consistent interpretation for Swift J1834.9-0846 and a new tool for understanding similar extreme
neutron stars.
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All authors Biaopeng Li, Zhifu Gao, Wenqi Ma, Weifeng Zhang, Quan Cheng, L.C. Garcia de Andrade
Instrumentation and Methods for Astrophysics
Mobile neutron monitor for latitude cosmic ray monitoring
Kobelev P.G., Maurchev E.A. and Yanke V.G
Neutron monitors are a standard tool for high-precision continuous monitoring of
galactic cosmic ray flux variations arising from variations in heliospheric conditions and
solar activity for space weather applications. These measurements form the basis for solving the inverse problem of determining the
cosmic ray anisotropy vector beyond the magnetosphere. To support such studies, periodic latitude measurements are necessary to determine the coupling functions of primary and secondary
cosmic rays variations. The aim of this work is to develop and characterize a modernized standard
neutron monitor based on a CHM-15 boron thermal
neutron counter and a data acquisition system designed for marine expeditionary studies of
cosmic ray variations. Modern
nuclear physics experimental methods and the principles of microprocessor-based data acquisition systems were used to solve this problem. The results of test trials and of continuous monitoring showed that the characteristics of the upgraded and standard
neutron monitor are similar, and the ease of use, compactness, and stability allow us to conclude that the mobile
neutron detector can be used in expeditionary conditions with limited access for maintenance personnel.
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Instrumentation and Methods for Astrophysics
SF2A Environmental Transition Commission: Summary of the 2025 workshop
Faustine Cantalloube, Jack Berat, Naïs Fargette et al. (+12 more)
During its annual conference in 2025, the French Society of Astronomy & Astrophysics (SF2A) hosted, for the fifth time, a special session dedicated to discussing the environmental transition within the French A&A research community. During the 2025 workshop, the goal was to review four contemporary topics within the context of environmental transition actions and discussions: (1) institutional actions, (2) the early-career researchers singularity, (3) research infrastructures and tools, and (4) the geopolitical conditions under which A&A research remains possible. The workshop concluded with a round-table discussion that brought together the various speakers so that every participant could express their ideas.
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All authors Faustine Cantalloube, Jack Berat, Naïs Fargette, Pierre Larue, N. Pourré, Sarah E Anderson, Julien Milli, Jean-François Gonzalez, Olivier Berné, Didier Barret, Angèle Mouinié, Clarisse Picard, Karine Dassas, Jürgen Knödlseder, David Redon
Cosmology and Nongalactic Astrophysics
Universality of Primordial Anisotropies in Gravitational Wave Background
Boyuan Jiang, Ryo Saito and Ying-li Zhang
We investigate the general structure of
primordial anisotropies in the
stochastic gravitational-wave background (SGWB). Many mechanisms generating
primordial SGWB anisotropies, including fossil and propagation effects, exhibit similar multipole dependences despite their distinct physical origins, implying the presence of a common underlying structure. To characterize this structure, we introduce a model-independent framework, the Cosmological Form Factor (CFF), that describes how long-wavelength perturbations modulate short-scale SGWB statistics. Within this broad class of mechanisms, we show that the allowed angular and polarization structures of SGWB anisotropies are universally determined by general principles, including statistical isotropy, locality, and the basic properties of long-wavelength perturbations. In contrast to these universal structures, observables such as amplitudes and frequency dependence retain information about the origin. Our results provide a unified and effective description of
primordial SGWB anisotropies, clarifying which aspects are universal and which are model dependent, and therefore offer a theoretical foundation for interpreting future gravitational-wave observations.
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