Solar and Stellar Astrophysics · Cross-listed from nucl-th
Confining density functional approach to the QCD phase diagram at low temperatures and thermal twin stars
David Blaschke and Oleksii Ivanytskyi
We present a density functional-based equation of state for warm, dense
nuclear matter with a transition to deconfined
quark matter for applications to simulations of
supernova explosions and
neutron star mergers, but also for the cosmological
evolution of Q-balls. For the
quark matter equation of state, we employ a recently developed confining density functional approach while
nuclear matter is described within a relativistic density functional model of the DD2 class. The phase transition is obtained by a Maxwell construction at constant
entropy per
baryon. We discuss the solutions of TOV equations for isentropic hybrid
stars for two hybrid equation of state models: DDf-SFM without and DD2-$\chi$CDF with color superconductivity. We find that at finite temperatures above a critical value of
entropy per
baryon sequences of disconnected third family branches ("thermal twin
stars") may appear for the DDf-SFM model, while they are absent for the color superconducting model and at $T=0$. We discuss the relation of this critical
entropy per
baryon to the Seidov criterion of gravitational instability for $T=0$ and find that it is a good guide. We suggest that the presence of thermal twin
stars may be regarded as an indicator for the core-collapse
supernova explodability of massive blue supergiant
stars with
solar metallicity and thus serve as a new criterion for the reliability of hybrid equation of state models. By this argument, strong color superconductivity shall be excluded and it remains to be shown whether models with moderate diquark pairing could fulfill the thermal twin constraint. For the case of symmetric matter, we compare the resulting hybrid EOS with the flow constraint by Danielewicz et al. and find a a sensitivity of the onset density for deconfinement to the presence or absence of color superconductivity.
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Solar and Stellar Astrophysics
The instantaneous mass accretion rate of novae in quiescence: - an archival ultraviolet optical spectral analysis
Patrick Godon, Edward M. Sion, Tim Naylor et al. (+1 more)
Based on archival spectra, we derive the quiescent instantaneous mass transfer rates in novae using synthetic disk spectra generated with tlusty,
Gaia parallax-derived distances, and updated color excess values. Our results for nine novae, based on ultraviolet spectra and on a number of optical spectra, yield mass
accretion rates that are higher than those derived from simple integration of the UV and optical luminosity. HR Del, 20 years after its eruption, has a mass transfer rate of $4\times 10^{-7}M_\odot$/yr, and is likely burning the accreting H-rich material. V842 Cen, thought to be a low mass transfer system, has a comparable mass
accretion rate. For both novae, the enhanced mass transfer must be self-sustained by a feedback loop. RR Pic, with $\dot{M}\approx 3\times 10^{-8}M_\odot$/yr, is better fitted with an
accretion disk where the outer region is heated up to 12,000 K, in agreement with H and He emission lines coming from the outer disk and a large emission region on the leading side of the disk. Such a heated disk also gives a good fit to the spectra of CP Lac, and DI Lac with $\dot{M}\sim4.5$ and $9\times 10^{-9}M_\odot$/yr. V1974 Cyg and V533 Her, with an
accretion rate of $\sim 3\times 10^{-9}M_\odot$/yr, have a rather flat spectrum. V446 Her and BK Lyn, caught in a state of low
accretion, have the lowest mass
accretion rates with $\dot{M} \sim 10^{-9}$ and $\sim 10^{-10}M_\odot$/yr respectively. The higher mass transfer rate systems, with $\dot{M}\approx \sim 10^{-7}M_\odot$/yr, agree with the standard disk model; the remaining systems are better fitted when the outer disk is heated to $\sim 12,000$~K. We suggest that irradiation from the heated WD, inner disk, together with
tidal interaction, the bright spot, and material overflowing the disk edge, can increase the temperature of the outer disk.
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All authors Patrick Godon, Edward M. Sion, Tim Naylor, Frederick A. Ringwald
Cosmology and Nongalactic Astrophysics
Imprints of Mass Accretion History on Galaxy Cluster Morphology
Kabelo Tsiane, Camille Avestruz, Elena Rasia et al. (+6 more)
Variations in dynamical states of
galaxy clusters can introduce biases and scatter in observable-mass relations. The dynamical state of a cluster is an emergent feature of its mass
accretion history (MAH), it is therefore useful to constrain the MAH of the cluster. In this work, we characterize 305 massive clusters from The300 project by connecting features from their projected
stellar distributions to their mass
accretion histories (MAH). As a baseline, we first correlate host dark matter
halo dynamical state indicators at $z=0$ with their MAH via the Spearman rank correlation coefficient $\rho_{\mathrm{sp}}$. Both substructure mass fraction and center-of-mass offset measurements correlate strongly with the MAH measured between $0.1\lesssim z\lesssim 1$. We repeat this exercise with morphological measurements of projected
stellar density maps, many of which exhibit moderate correlation strength with different times in the MAH. Broadly, core morphological measurements ($r \leq 30\,\mathrm{kpc}$) correlate better with early-time MAH. Core-excised ($50\,\mathrm{kpc} \leq r \leq 1\,\mathrm{Mpc}$) morphological measurements correlate better with late-time MAH. We further quantify the MAH prediction power of both traditional dynamical state indicators and morphological parameters using Multivariable Conditional Abundance Matching (MultiCAM). MultiCAM employs simple rank-ordering operations, making it straightforward to translate to observed
datasets. We find reasonable ($\rho_{\mathrm{sp}} \geq 0.6$) performance for predictions of the mass fraction between $1\lesssim z\lesssim 0.1$, though with notable information loss when using projected quantities. In one example application of our methodology, we use the coefficients of the MultiCAM models to select subsamples of
galaxy clusters that have accreted more (or less) of their $z = 0$ mass budget over a given time frame.
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All authors Kabelo Tsiane, Camille Avestruz, Elena Rasia, Roan Haggar, Jesse B. Golden-Marx, Guillaume Mahler, Elizaveta Sazonova, James Taylor, Massimo Meneghetti
Instrumentation and Methods for Astrophysics
The Roman Coronagraph Community Participation Program: data reduction pipeline astrometric calibration
Amanda Chavez, Jason Wang, Vanessa P. Bailey et al. (+5 more)
The Nancy Grace Roman Space
Telescope will be equipped with a Technology Demonstration Coronagraph Instrument that will push the current limits of high contrast imaging for
exoplanets ($10^{-9}$ contrast). The Roman Coronagraph Community Participation Program has developed corgidrp, a python-based data reduction pipeline for the Roman Coronagraph Instrument that will perform essential data processing and calibration steps for coronagraphic observations. The astrometric calibration function within corgidrp allows us to understand the on-sky angular size and distance scale of science observations by characterizing essential detector parameters: boresight, plate scale, north angle, and optical distortion. Measuring these astrometric calibration products not only helps us understand the science output of our data, but it is what allows us to point the Roman coronagraph accurately at our science target in the first place. Here, we describe the techniques used within the astrometric calibration and demonstrate that our
algorithm meets Technology Demonstration Threshold Requirements: (1) compute the on-sky location of the center of CGI EXCAM detector to better than 30 [mas] and (2) compute the on-sky position angles of the camera axes to within 0.3 [deg].
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All authors Amanda Chavez, Jason Wang, Vanessa P. Bailey, Maxwell Millar-Blanchaer, Julien Girard, John Krist, Julia Milton, Marie Ygouf
Astrophysics of Galaxies
The Spin Angular Momentum and Black Hole Mass Components of Sagittarius A*
Ruth A. Daly
The dimensionless
spin angular momentum, dimensionless
spin function, and blackhole mass components of Sagittarius A* (Sgr A*) were obtained by Daly et al. (2024) by applying the
outflow method to six independent sets of simultaneously or contemporaneously obtained X-ray and
radio data. Here, results obtained for Sgr A* with the
outflow method are reviewed. Consistent results were obtained with each data set. Set I (the preferred data set) indicates that Sgr A* has a dimensionless
spin angular momentum $a_* = (0.90 ~\pm~ 0.06)$ and a dimensionless
spin function $F = (0.62 ~\pm~ 0.10)$. The results are consistent with the value of $a_* = (0.93~\pm~ 0.15)$ obtained with the
outflow method applied to an independent data set (Daly 2019). The application of the
outflow method to a weak compact
radio source such as Sgr A* in its current state is most accurately determined with simultaneous or contemporaneous
radio and X-ray measurements.
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High Energy Astrophysical Phenomena
Evidence of self-organized criticality in the prompt emission of a bright gamma-ray burst
Wen-Long Zhang, Wen-Jun Tan, Hao-Tian Lan et al. (+18 more)
Gamma-ray bursts (GRBs) are the most energetic explosive events in the Universe, yet the physical mechanism of their
prompt emission remains a mystery. Especially, it is unclear whether the energy dissipation mechanism in the GRB jet is dominated by kinetic energy or
magnetic energy. Here, we studied the pulses in the
prompt emission of the second brightest GRB to date, GRB 230307A, which was accurately measured by the Gravitational wave high-energy electromagnetic counterpart all-sky monitor (GECAM), with focus on the cumulative distributions of peak counts and duration of pulses as well as the waiting time between pulses. We find that these cumulative distributions show scale-invariant behavior, well consistent with the prediction of the self-organized criticality (SOC) theory. This is the first robust evidence of an SOC feature in the
prompt emission of a single GRB. Moreover, the statistical properties of pulses in the
prompt emission of GRB 230307A are very similar to those of
solar flares. Our findings suggest that the
prompt emission of GRB is powered by the dissipation of
magnetic energy in the ultra-relativistic jet, supporting the Poynting-flux-dominated
prompt models.
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All authors Wen-Long Zhang, Wen-Jun Tan, Hao-Tian Lan, Shuang-Xi Yi, Shao-Lin Xiong, Chen-Wei Wang, Shuang-Nan Zhang, C. Guidorzi, R. Maccary, R. Moradi, Cheng-Kui Li, Sheng-Lun Xie, Wang-Chen Xue, Jia-Cong Liu, Zheng-Hang Yu, Yue Wang, Peng Zhang, Yan-Qiu Zhang, Chao Zheng, Jin-Peng Zhang, Fa-Yin Wang
Solar and Stellar Astrophysics
Observations of Disrupted CME Material Falling Back Into the Low Corona
Brian E. Wood and Jason E. Kooi
We present an empirical study of a disrupted CME, parts of which fall back to the Sun, using observations from SOHO, STEREO-A, and SDO. At UT 18:00 on 2024 August 16, a slow CME is overtaken by a faster CME. A leg of the second CME carries part of the slower CME out with it, resulting in an unusually well-defined flux rope leg for this CME. This second CME is observed in
radio by the VLA, with Faraday rotation measurements showing a clear
magnetic flux rope signature. A strong response is also later seen when the
radio-observed line of sight enters the CME leg enriched by material from the disrupted CME. Outside this leg, the rest of the disrupted CME simply disappears and is replaced by a large number of small jet-like downflows. We see clear evidence of this
plasma falling back to the low corona in EUV images from SDO, roughly 6-17 hours after the CME is disrupted, with an inferred downward velocity of V=-30 km/s. There is a clear temperature dependence, with the downflows seen first in the 211 bandpass, followed successively by responses at 193, 171, and 304. The downflows are much slower than would be expected for a ballistic descent, so we model the downflows using a kinematic drag model. In the 304 bandpass, coronal rain activity is triggered by the downflowing CME material, suggesting that downflows from the upper corona could be contributing to coronal rain more generally.
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Instrumentation and Methods for Astrophysics
Vera C. Rubin LSST Synthetic Magnitudes derived from Gaia XP Spectra
Oleksandra Razim, Krešimir Tisanič and Lovro Palaversa
Context. In the context of Milky Way studies, the Vera C. Rubin Observatory's Legacy Survey of Space and Time is often described as a deep extension of the
Gaia survey. In the future, joint analysis of the
Gaia and LSST data promises to bring new insights into our understanding of the
Galaxy's structure and formation history. However, the relatively small overlap in the magnitude ranges of the two surveys raises the question of how to perform a joint calibration of these
datasets. Aims. In this paper, we produce high-quality synthetic LSST photometry from
Gaia XP low-resolution spectra, using SDSS and DES observed photometry to calibrate the spectra. Methods. We develop a method of empirical correction of
Gaia XP spectra using SDSS Stripe 82 photometry. We project sources for which
Gaia XP data are available onto a magnitude-magnitude grid and calculate residuals between uncorrected synthetic and observed SDSS magnitudes, which are then used to derive correction coefficients across spectral regions corresponding to each photometric band. Results. The correction significantly reduces systematic trends and scatter in the synthetic magnitudes: the median residuals decrease by an order of magnitude (e.g., for the u band the improvement is from 0.038 to 0.002 mag), and the standard deviation of residuals typically becomes up to factor of two smaller (e.g., for the u band from 0.2 to 0.07 mag). Conclusions. Our correction approach improves the reliability of synthetic photometry derived from
Gaia XP spectra and enables joint analysis of
Gaia and LSST data for studies of
Galactic structure and
stellar populations.
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Earth and Planetary Astrophysics
Hydrodynamics modeling of the water snow line in young protoplanetary disks with dust-size-dependent opacities
Eduard I. Vorobyov, Anastasiia Topchieva, Aleksandr Skliarevskii et al. (+2 more)
Aims. We investigated the properties of the water snow line during the early stages of disk
evolution, paying particular
attention to the effects of gravitational instability and
dust growth on the snow line's shape and position. Methods. We used the FEOSAD numerical hydrodynamics code to simulate the disk formation and
evolution in the thin-disk limit. The simulations incorporate the coevolution of gas,
dust, and volatiles, including
dust growth, volatile phase transitions, and
dust-size-dependent opacities. Results. The position of the water snow line is highly nonsteady during the considered disk
evolution period, first moving outward during the disk build-up and then retreating back as the disk cools. Its form in the disk midplane deviates strongly from a circular shape in the early gravitationally unstable phase of disk
evolution. An increase in the amounts of grown
dust and water ice as well as in the maximum
dust size just beyond the snow line, as is readily observed in one-dimensional viscous disk
evolution models, in our hydrodynamic models occurs only after gravitational instability diminishes.
Dust-growth-induced opacity changes have a profound effect on the position of the water snow line, shifting it closer to the
star by almost a factor of two compared to models that do not take this effect into account. Conclusions. The shape, position, and properties of the water snow line in young, gravitationally unstable disks differ from those of older, axisymmetric disks. Our results highlight the importance of taking into account the dependence of opacity on
dust size when studying disk
evolution.
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All authors Eduard I. Vorobyov, Anastasiia Topchieva, Aleksandr Skliarevskii, Yaroslav Pavlyuchenkov, Konstanze Zwintz
Astrophysics of Galaxies
The segmented spiral structure of the Solar neighbourhood traced by young clustered populations
M. Carmen Sánchez-Gil and Emilio J. Alfaro
The Milky Way spiral pattern remains poorly constrained, and the youngest tracers in the
solar neighbourhood do not always follow a few smooth, continuous logarithmic arms. We analyse young open clusters, both independently and combined with young
stellar object (YSO)-based groups, to test whether they define continuous spiral-arm ridges or shorter, partially connected structures. In the (theta_G, ln R_G) plane, we identify local overdensities using a density-supported
Bayesian Gaussian Mixture Model (BGMM), introducing published Perseus, Local, Sagittarius, and Scutum arm tracks only afterwards as reference curves. We then apply a Minimum Spanning Tree (MST) analysis in the heliocentric (X,Y) plane to examine spatial connectivity. The open-cluster sample already resolves into several local components, while the addition of YSO-based groups highlights branches and intermediate regions without producing continuous arms. The MST likewise shows distinct local branches at small
pruning scales that progressively merge as the linking scale increases. The Local–Sagittarius region provides the clearest agreement between both diagnostics: the BGMM identifies an intermediate component between the reference arms, while the MST connects neighbouring branches through the same region. Overall, young structures near the Sun appear as fragmented, spiral-like segments with partial links rather than smooth continuations of a few grand-design arms. Determining whether this morphology reflects spiral-arm formation mechanisms or subsequent
evolution will require additional age, vertical, and kinematic information.
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Astrophysics of Galaxies
Concerns regarding recurrent fluorescence's impact on smaller diffuse ISM aromatics
Daniel Majaess, Cercis Morera-Boado, Tina A. Harriott et al. (+1 more)
Recent research implied that recurrent fluorescence (RF) could bolster smaller aromatics against fragmentation in the diffuse ISM, yet that hypothesis is contested by timescales for unrelenting dissociative recombination (electrons), and unceasing dissociating
photons. Specifically, neutral cyanonaphthalene can sustain $13.6$ eV photoionization, and the ensuing cation's excess energy is channeled through intramolecular vibrational redistribution (IVR), with RF providing the radiative stabilization pathway ($\simeq7$ eV negligible survival limit). However, that cation endures dissociative recombination every $\tau\approx0.5^{+5.6}_{-0.4}$ years, which deposits $\simeq 8.6$ eV and exceeds the limit. Moreover, that is paired with $7-13.6$ eV photodestruction each $\tau\approx16^{+223}_{-14}$ years (total visual
dust extinction $A_V=0-1$, and $\tau\approx4^{+7}_{-2}$ years for $A_V\approx0$). Recent laboratory characterizations of RF were seminal, but the mechanism may not overturn models indicating a gap in smaller $N_C\approx7-11$ diffuse ISM aromatics, nor support those molecules as viable diffuse interstellar band carriers.
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All authors Daniel Majaess, Cercis Morera-Boado, Tina A. Harriott, Cherif F. Matta
Cosmology and Nongalactic Astrophysics · Cross-listed from hep-th
A compact analytic formula for the one-loop triangle cosmological correlator
Johannes Henn, Jiajie Mei and Qinglin Yang
We derive a compact analytic formula for the one-loop triangle correlator of conformally coupled scalars in de Sitter space. The result is organised as six leading-singularity prefactors multiplying pure weight-two functions of the six energy variables. It contains forty-two dilogarithms, compared with approximately one hundred and twenty in the previously known closed-form representation, and requires no auxiliary regulator. The dilogarithms occur in Galois-conjugate pairs, making each contribution separately real throughout the physical region. We validate the result numerically. Moreover, we show that its symbol can be derived directly from the dressed integral representation or, independently, bootstrapped from Landau singularities and general consistency conditions. Finally, we show that the correlator (in a suitable normalization) is a Stieltjes function of each squared energy separately and is jointly completely monotone in all six squared energies. These structures suggest a route towards higher-point one-loop cosmological correlators.
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Astrophysics of Galaxies
The Stellar Population of NGC 346 in the Small Magellanic Cloud with JWST
J. Jaspers, P. Kavanagh, G. De Marchi et al. (+13 more)
NGC 346 is a massive
star-forming region located at a distance of $\sim$62 kpc, in the Small Magellanic Cloud (SMC). Due to its low
metallicity (Z $\sim$1/5 Z$_{\odot}$), it is an ideal environment to study
star formation and
stellar population analogues to those at
Cosmic Noon. In this work, we produce a combined JWST NIRCam and MIRI photometric catalogue of NGC 346. We characterise different
stellar populations in the region: the upper main sequence (UMS), red
giant branch (RGB), and red clump (RC), as well as pre-main sequence (pre-MS)
stars and young
stellar objects (YSOs). We performed point-spread function (PSF) weighted photometry in 11 wavelength bands across NIRCam and MIRI and utilised multiple colour-magnitude-diagrams to identify the various
stellar populations in the field. Our final photometric catalogue of NGC 346 comprises 249,519 unique sources, including 2,024 UMS
stars, 2,755 RGB
stars and 742 RC
stars. In addition, we identified 6,274 candidate pre-MS
stars, 7,350 candidate YSOs and 23,819 IR-excess sources. Combining these three categories, we characterised 1,583 strong and 3,761 likely pre-MS/YSO candidates. By utilising the F115W-F200W vs F115W-F187N colour-colour diagram, we found 239 non-spurious sources with Pa$\alpha$ excess, indicating
accretion and
star formation in NGC 346. Using JWST NIRCam and MIRI observations, we produced the deepest catalogue to date of the
star formation region NGC 346 in the near- and mid-IR range (1-21$~\mu$m). Our catalogue and characterisations of the young and old populations will provide the basis for detailed follow-up studies.
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All authors J. Jaspers, P. Kavanagh, G. De Marchi, C. Nally, O. Jones, N. Habel, P. Zeidler, M. Meixner, E. Sabbi, A. Hirschauer, K. Biazzo, L. Lenkic, O. Nayak, M. Roberto, C. Rogers, B. Sargent
Solar and Stellar Astrophysics
3D simulations of magnetospheric accretion in T Tauri stars: I. Disk truncation, stellar torques, and application to observations
George Pantolmos, Claudio Zanni and Jérôme Bouvier
Young
stars accrete material from their circumstellar disk through their magnetosphere and undergo contraction; these two processes impact their rotational
evolution. We investigate stable and unstable
accretion regimes (due to the interchange instability) and examine the associated
stellar torques to assess the
spin evolution of young
stars. We performed 3D MHD simulations of disk
accretion onto an inclined
stellar dipole. We ran 21 simulations with varying
stellar rotation rates, dipole field strengths and obliquities, and mass
accretion rates. We find that
stars with a ratio of truncation to corotation radius $R_t/R_{co} \gtrsim 0.80-0.85$ accrete via a stable regime, while
accretion becomes unstable otherwise. In addition, our $R_t/R_{\ast}$ parametrization weakly depends on the mass
accretion rate and the dipolar intensity, while strongly depending on the
stellar rotation rate. We derive torque formulae for each flow component affecting the
stellar rotation, i.e.,
accretion, magnetospheric ejections and
stellar winds. Finally, we apply our results to a sample of young
stars with measured
magnetic fields, mass
accretion rates, and rotational periods and find that most of them should currently accrete in an unstable regime and undergo
spin-up torques. Our study confirms and expands upon previous results. Unstable
accretion should lead to a net
spin-up torque on the central
star, while stable
accretion can lead to
stellar spin-down. When applying our truncation radius and torque prescriptions to observational data, we find that most young
stars in our sample should be in a
spin-up state. Thus, the angular momentum problem for young
stars remains.
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Earth and Planetary Astrophysics
Triggered Fragmentation in Self-Gravitating Protoplanetary discs: Cooling, Mass Movement and Instability
Pratishtha Rawat, Farzana Meru and Rebecca Nealon
Previous three-dimensional hydrodynamical simulations of gravitationally unstable discs have shown that the formation of a single fragment can trigger the formation of subsequent fragments. This behaviour was attributed to changes in the surface mass density caused by the interaction between the first fragment and the disc material. This study reanalyses those simulations to see if the surface mass density was the sole driver. Our results reveal that both surface mass density and sound speed can contribute to the formation of additional fragments. Beyond the general cooling typical of such discs, the inwards movement of cool material from the outer disc, driven by the formation of the first fragment, can enhance fragmentation in the inner regions. We also identify that interactions between the midplane gas and the cooler upper layers of the disc can facilitate additional cooling. Triggered fragmentation can create a unique
planet-formation environment by redistributing material across the disc, potentially leading to chemically distinct fragments from those formed in-situ.
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Instrumentation and Methods for Astrophysics
Accurately simulating gain and clock-induced charge production in the EMCCD gain register
Kevin J. Ludwick
An electron-multiplying charge-coupled device (EMCCD) is capable of precise detections in low-signal environments, able to detect a single
photon through electron multiplication. It has many applications, such as faint-target astronomy,
quantum optics, molecule tracing, and others, and it will be used for faint companion detection in the Roman
Telescope's coronagraph instrument. In an EMCCD,
photons hit the pixels, and photo-electrons are created; these are multiplied via impact ionization as they travel through the gain register from one gain stage to the next. A high gain means a high multiplication factor, and this is achieved through a high voltage difference across a gain stage. If the gain is high enough, the chance of clock-induced charge (CIC) production in the gain register increases. The probability distribution function governing the gain process typically used only accounts for charge multiplication if one or more electrons enter the gain register. I discuss my implementation of the simulation of this effect and its customization in emccd_detect, the EMCCD detector simulator used for the Roman
Telescope. In addition, the simulator has been updated to use the exact binomial distribution for EM gain instead of the approximate Gamma distribution usually used in the literature, which is only valid for large counts. I also examine some EMCCD data and show through maximum likelihood estimation with CIC_gain_register that the data conform better to the binomial distribution versus the approximate Gamma/Erlang distribution. The use of the modified distribution would in principle improve the fidelity of Roman's testing and lead to better EMCCD calibration and more accurate signal extraction from a frame.
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Instrumentation and Methods for Astrophysics
Simulation tools for realistic high-order wavefront correction with the Roman Coronagraph
A. Lau, A. J. Riggs, S. F. Redmond et al. (+9 more)
The Roman Space
Telescope Coronagraph Instrument (Roman CGI) will demonstrate high-contrast imaging from space using coronagraphic masks, deformable mirrors, and high-order wavefront sensing and control (HOWFSC). After the baseline technology demonstration, the Roman Coronagraph Community Participation Program (CPP) will pursue science and engineering studies that require realistic predictions of instrument behaviour, observing efficiency, and wavefront control performance. This paper describes corgihowfsc, a configurable simulation framework for repeatable Roman CGI HOWFSC studies. The framework preserves the Roman ground-in-the-loop (GITL) workflow represented by the NASA cgi-howfsc package, while allowing the images to be generated by the higher-fidelity corgisim model. In this configuration, cgi-howfsc remains the reference implementation for estimation, control, and compact-model Jacobian generation; corgisim can supply more flight-like images for studies of instrument performance and robustness. corgihowfsc also coordinates exposure planning, camera settings, expected iteration timing, and contrast normalisation of the HOWFSC loop through cgi-eetc, calibration-related workflows through cgi-coralign, structured diagnostics, and local or distributed execution. By exposing observing modes, image models, probe choices,
estimators, controllers, deformable-mirror settings, and runtime options through reusable configuration files, corgihowfsc enables controlled comparisons between reference compact-model simulations and higher-fidelity HOWFSC studies.
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All authors A. Lau, A. J. Riggs, S. F. Redmond, E. Cady, J. Krist, I. Laginja, D. Sirbu, L. Delaye, R. Soummer, S. Noiret, J. C. Lambert, A. Bidot
High Energy Astrophysical Phenomena
The high entropy of the UHECR arrival direction distribution favors a light composition
Nimrod Strasman and Eli Waxman
We analyze the constraints on the composition of ultra-high-energy
cosmic rays (UHECRs), and on the density and distribution of their sources, that may be inferred from their arrival-direction distribution, using a novel semi-analytical description of the propagation energy loss of atomic
nuclei ($A>4$) with energy $>2\times10^{19}~\text{eV}$, that allows generating UHECR arrival maps faster than by using detailed propagation simulations and yields insights to the impact of propagation energy loss. We show that the anisotropy of the UHECR arrival direction distribution due to the large-scale structure (LSS) of matter distribution is larger for heavy
nuclei composition compared to
protons, despite their larger deflections by
magnetic fields, due to their shorter propagation distance and weaker dependence of
rigidity on observed energy. Identifying the LSS anisotropy signal is hampered for heavy
nuclei due to their large deflections by the uncertain
Galactic magnetic field (GMF). We introduce a new measure of anisotropy, an "
entropy" of the arrival-direction distribution, that is largely independent of the GMF configuration and has strong discriminating power between heavy- and light-composition models. Analyzing the public $>3.2\times10^{19}$~eV Auger data, we show that the correlation with the LSS on large angular scales is weak and requires a low source density, $s_0\le10^{-4}{\rm Mpc}^{-3}$, to allow masking the LSS signature by "
cosmic-variance" ($s_0=10^{-2}{\rm Mpc}^{-3}$ is ruled out at $>99\%$ confidence level (CL)). The high
entropy of the distribution is consistent with
proton models and inconsistent with heavy
nuclei models at $>96\%$ CL for $s_0\ge10^{-5}{\rm Mpc}^{-3}$. Reducing the absolute energy calibration uncertainty may allow detection of the LSS correlation for
proton models (increased exposure alone will not suffice due to the dominance of
cosmic variance).
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High Energy Astrophysical Phenomena · Cross-listed from nucl-ex
Revised $^{45}$V($p,\gamma$)$^{46}$Cr reaction rate and its impact on the production of $^{44}$Ti in core-collapse supernovae
R.S. Sidhu, Y. Luo, C. Sarma et al. (+2 more)
The thermonuclear $^{45}$V($p,\gamma$)$^{46}$Cr reaction is the primary leakage pathway from the $^{44}$Ti–$^{45}$V quasi-
equilibrium cluster during $\alpha$-rich freeze-out in core-collapse
supernovae (CCSN), governing the final abundance of the $\gamma$-ray-emitting isotope $^{44}$Ti. A recent high-resolution $\gamma$-ray study [C. Cousins et al., Phys. Rev. Lett. 136, 252701 (2026)] identified ten previously unknown low-
spin proton-unbound states in $^{46}$Cr, enabling the first experimentally constrained $^{45}$V($p,\gamma$)$^{46}$Cr reaction rate using the AME2020 mass excess, $\text{ME}(^{46}\text{Cr}) = -29472(11)$~keV. Here, we adopt the four-fold more precise CSRe mass excess $\text{ME}(^{46}\text{Cr}) = -29477.2(2.6)$~keV [M.~Wang et al., Phys. Rev. C 106, L051301 (2022)] to recalculate the reaction rate. Including
proton capture on the ground and first two excited states of $^{45}$V alongside new shell-model
proton spectroscopic factors, we reduce mass-related rate uncertainties to a subdominant level. The revised rate is up to 69% higher than that of Cousins et al. at $\alpha$-rich freeze-out temperatures ($T \simeq 1.5$–$2$~GK). CCSN nucleosynthesis calculations show this revised rate increases the ejected $^{44}$Ti yield by $\sim$26% in a $20\,M_\odot$ model compared to The et al. [ApJ 504, 500 (1998)], while causing negligible changes for the SN~1987A trajectory. We demonstrate that $^{44}$Ti production sensitivity is dictated by the ejecta electron fraction ($Y_e$): the reaction significantly affects
proton-rich ejecta ($Y_e \approx 0.50$) but has little impact on
neutron-rich ejecta ($Y_e \approx 0.496$), where lower free-
proton abundances suppress reaction flow. This reconciles conflicting results from past sensitivity studies.
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All authors R.S. Sidhu, Y. Luo, C. Sarma, M. Wiescher, X. Xu
Instrumentation and Methods for Astrophysics
The Roman Coronagraph Community Participation Program: Using the Zernike wavefront sensor for a full characterisation of the Roman Space Telescope and the Coronagraph Instrument
Arthur Vigan, Alexis Bidot, Vincent Chambouleyron et al. (+4 more)
The Roman Space
Telescope Coronagraph Instrument (CGI) will demonstrate a series of technologies and techniques to enable the direct detection of reflected-light
planets with space-based observatories. Among the several available observing modes and coronagraphic devices embarked in CGI, there is the transmissive dual-path Zernike wavefront sensor (ZWFS) that could be used to directly measure optical aberrations in the system. The dual-path ZWFS is currently unsupported, but in this work we advocate for the commissioning of this unique observing mode. We investigate the sensitivity of the ZWFS using CGI simulator and other tools developed and supported by the Roman community participation program (CPP). This type of analysis is crucial for understanding the stability of the Roman observatory and to prepare the path towards HWO.
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All authors Arthur Vigan, Alexis Bidot, Vincent Chambouleyron, Garreth Ruane, Laurent Pueyo, Mamadou N'Diaye, Kjetil Dohlen
High Energy Astrophysical Phenomena
The initial evolution of SN 2011dh: The importance of inhomogeneities
Claes-Ingvar Bjornsson
SN 2011dh is rather unique in that it offered detailed observations of the initial phase in the
radio as well as optical regimes. This makes possible a comparison between models used to deduce properties of the outer envelope of the
supernova ejecta. It is shown that a consistent description suggests the forward shock to have started in the piston phase with constant velocity, and only later, around 50 days, transitioned to the standard model, which is independent of initial conditions. In addition, observations imply that the
radio source is inhomogeneous with a covering factor of, approximately, 50%. It is emphasised that the deduced properties of the synchrotron source are very sensitive to the presence of inhomogeneities; for example, a covering factor of 50% increases the ratio of the energy densities of relativistic electrons and
magnetic field by several orders of magnitude as compared to a homogeneous source. The shallow density gradient in the envelope causes substantial deceleration of the forward shock. This is used to argue that the
magnetic field strength scales inversely with radius rather than inversely with time; this is similar to SN 1993J.
Attention is also drawn to the similarities between the flat spectra of compact, extragalatic
radio sources and the
evolution of
radio supernovae; e.g., the scaling of the
magnetic field and the constant brightness temperature.
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Cosmology and Nongalactic Astrophysics
eROSITA cosmology with galaxy groups: Hot gas budget out to the virial radius
H. Khalil, A. Finoguenov, D. Eckert et al. (+4 more)
Non-gravitational processes that expel hot gas beyond the virial regions of groups and clusters of
galaxies, known collectively as baryonic feedback, play a key role in reshaping the matter distribution of the Universe on Mpc scales. We use eROSITA observations of a complete sample of 25
galaxy groups selected from the first public release of the eROSITA-DE data (eRASS1) and identified with the Two Micron
Redshift Survey optical group catalogue (2MRS). We extract and fit surface brightness (SBx) profiles and present hot gas mass and hot gas fraction profiles out to $R_{200}$. We perform a
Bayesian analysis of $M_{\mathrm{gas}}-M_{\mathrm{tot}}$, $L_{\mathrm{X}}-M_{\mathrm{tot}}$, and $L_{\mathrm{X}}-M_{\mathrm{gas}}$ relations, taking into account the aperture covariance effects. At $R_{500}$, we report uniformly flat SBx profiles with a mean $\beta$ parameter of $0.38 \pm0.04$, steepening to $\beta = 0.76\pm0.19$ beyond $R_{500}$. We measure a sub-
cosmic hot gas fraction at the median mass of our sample $M_{500} = 2.54\times10^{13}M_{\odot}$ of $ f_{\mathrm{gas,500}} = 4.32\pm0.42\%$. Similarly, at $R_{200}$ and the median mass $M_{\mathrm{ 200}} = 3.69\times10^{13}M_{\odot}$, we obtain $f_{\mathrm{gas,200}}=5.78\pm0.69\%$. Our $f_{\mathrm{gas}}-M_{\mathrm{tot}}$ and $L_{\mathrm{X}}-M_{\mathrm{tot}}$ relations show significant deviations from the predictions of the strong feedback variants of the FLAMINGO simulation ($2.5\sigma$ to $8.0\sigma$ tension), while fiducial FLAMINGO and BAHAMAS provide the closest match to our measurements. Using our measured
baryon fractions and the SP(k) model, we infer a $10\%-15\%$ reduction in the matter power spectrum at $k = 5\ h\ \mathrm{Mpc}^{-1}$ relative to a dark matter-only universe, in agreement with fiducial FLAMINGO and BAHAMAS, while revealing a growing tension on smaller scales with the strong feedback variants.
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All authors H. Khalil, A. Finoguenov, D. Eckert, R. Seppi, E. Tempel, L. Lovisari, F. Gastaldello
Solar and Stellar Astrophysics
A Catalog of Homogeneously Derived Stellar Parameters for Spectroscopic Survey Stars
Stefan Y. Stefanov, Evelina Zaharieva, Djemma Ruseva et al. (+9 more)
Uniformly derived
stellar parameters are vital for
exoplanet demographic studies because they directly influence the inferred planetary masses, radii, and bulk densities. This study presents a new homogeneous catalog of physical
stellar parameters for 5533 single
stars observed by the HARPS, HIRES, and CARMENES radial-velocity (RV) surveys.
Stellar parameters are determined using a
Bayesian framework with two independent sets of
stellar evolutionary models: MIST and PARSEC, using published spectroscopic parameter estimates and catalog values as priors. The resulting
stellar effective temperatures, masses, radii, and surface gravities are compared and evaluated for consistency with
stellar parameters listed in major
exoplanet catalogs. While our estimates show consistency with those listed in external catalogs, we identify method-dependent differences in
stellar masses for low-mass and pre-main-sequence
stars, as well as G and K
giants, where isochrone-based solutions may be affected by age-mass degeneracies. For low-mass
stars such as M-
dwarfs, the catalog provides masses derived from established mass-luminosity empirical relations, which tend to be more reliable. This catalog provides the largest uniformly derived
stellar reference sample for Doppler survey targets and also illustrates the applicability and limitations of
stellar-parameter homogenisation methods for future RV
exoplanet demographics studies.
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All authors Stefan Y. Stefanov, Evelina Zaharieva, Djemma Ruseva, Milen Minev, Denitza Stoeva, Volker Perdelwitz, Lev Tal-Or, Jerusalem T. Teklu, Elena Vchkova Bebekovska, Desislava Antonova, Vladimir Bozhilov, Trifon Trifonov
Cosmology and Nongalactic Astrophysics
Large eROSITA X-ray sources as 2MRS galaxy groups
A. Finoguenov, R. Seppi, D. Eckert et al. (+5 more)
We aim to exploit the large area coverage, good sensitivity, and low instrumental background of eROSITA to detect the faint surface brightness emission of
galaxy groups from the Two Micron All Sky Survey
Redshift Survey (2MRS). Using the data from eROSITA-DE Data Release 1, including images, exposure maps, and local background maps, we performed a wavelet decomposition of image mosaics in the 0.6–2.3 keV band at angular scales of 1/8-16'. We adopted 8-16' scales for source detection and 2-4' scales to improve catalog purity. A novel identification method based on the ranked partial Hausdorff distance fully exploits the X-ray image and group membership information. Random catalogs were used to control match purity, and the identification threshold was chosen to maximize the catalog size at a fixed purity. {We present a catalog of 619 X-ray
galaxy groups with 80% purity, and define subsamples with 90% and 97% purity. Bright sources closely match the AXES-2MRS catalog (which is based on ROSAT All Sky Survey data analysis on spatial scales of 12-24'). The X-ray luminosity function of our groups agrees with previous studies down to 5.e41 erg/s. Using dynamical mass estimates, we find that the X-ray counterpart completeness for groups with >=4 members exceeds 60% for masses >2e13 Msun. We modeled the 2MRS group catalog and justify the inclusion of two-member groups in the identification. This study demonstrates that large X-ray sources on spatial scales relevant for cosmological studies of baryonic distributions can be reliably detected and identified using nearby
galaxy group catalogs.
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All authors A. Finoguenov, R. Seppi, D. Eckert, H. Khalil, J. Kosowski, E. Tempel, F. Gastaldello, L. Lovisari
Earth and Planetary Astrophysics · Cross-listed from physics.hist-ph
Astrobiology and the Transformation of Scientific Epistemology
Kristina Šekrst
Astrobiology occupies an unusual position within the philosophy of science. Confronted with the n = 1 problem - having only a single example of life to study - it attempts to investigate life beyond Earth while relying entirely on Earth's biosphere as its reference point, a constraint that creates unique epistemic challenges. Unlike traditional sciences with clear predictive frameworks, astrobiology operates as what we might call a transient science: a discipline functioning without foundational certainties, relying predominantly on abductive
reasoning, and confronting hypotheses that may remain untestable for decades. It is, in essence, a science of absence - of evidence, certainty, and analogy - where progress lies in refining conceptual and experimental tools to recognize unfamiliar forms of life. This positions astrobiology alongside emerging fields like artificial intelligence and cognitive science within a broader transformation of how scientific knowledge is constructed when dealing with phenomena that transcend direct empirical access.
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Cosmology and Nongalactic Astrophysics · Cross-listed from hep-ph
VERaiPHY – Validation & Evaluation for Robust AI in PHYsics
Gaia Grosso, Ramon Winterhalder, Lydia Brenner et al. (+2 more)
Modern machine learning is leading to substantial gains in precision, flexibility, and computational efficiency in fundamental physics. Statistical validation, uncertainty quantification, and robustness assessment are less systematically addressed. The VERaiPHY initiative (Validation & Evaluation for Robust AI in PHYsics) is a series of articles developed within the PHYSTAT programme, aimed at establishing statistical standards for the development, evaluation, and deployment of ML techniques. Each article focuses on a specific methodological domain from a statistics perspective and clarifies statistical questions, tests, and the interpretation of results. This opening article establishes the probabilistic, statistical, and machine learning foundations that the later contributions assume, together with the notation used throughout.
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All authors Gaia Grosso, Ramon Winterhalder, Lydia Brenner, Louis Lyons, Tilman Plehn
Earth and Planetary Astrophysics
Radar observations of Europa in 2011-2024: New insights into radar scattering properties
Tunhui Xie, Jean-Luc Margot, Sebastiano Padovan et al. (+5 more)
Three of Jupiter's Galilean satellites - Europa, Ganymede, and Callisto - are of particular scientific interest due to their icy shells and suspected subsurface oceans. However, the radar properties of the icy satellites have not been measured since observations in 1987-1991. Because
radio waves can penetrate pure ice to considerable depths, radar observations provide a powerful means of characterizing the subsurface properties of the icy shells of these satellites, offering key insights into planetary
evolution. We have observed Europa using the Goldstone 3.5-cm
Solar System Radar and the Green Bank
Telescope (GBT) in 2011-2024 in order to address a longstanding gap in the radar studies of these moons. In this paper, we present the most longitudinally comprehensive set of radar measurements of Europa to date and describe its disk-integrated radar properties. On the basis of monostatic Goldstone data, we find radar albedo values in two circular polarizations of $\hat\sigma_{\rm OC}$ = 0.92 $\pm$ 0.11 and $\hat\sigma_{\rm SC}$ = 1.35 $\pm$ 0.13 (unweighted mean and root-mean-square dispersion), with a circular polarization ratio of $\mu_c$ = 1.44 $\pm$ 0.12 (weighted mean and root-mean-square dispersion). Values obtained bistatically at the GBT are similar. The $\mu_c$ values suggest a leading-vs-trailing side dichotomy in radar scattering properties on Europa. Our results support the existence of the coherent backscatter opposition effect (CBOE), currently the most widely accepted physical mechanism that explains the unusual radar scattering properties of the icy Galilean satellites. Because we observed Europa with a bistatic configuration, we can place a lower bound on the width of Europa's CBOE peak equal to 36 arcsec, which provides an upper bound of 32 m ($\sim$1000 wavelengths) on the penetrating depth of X-band radar waves at Europa.
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All authors Tunhui Xie, Jean-Luc Margot, Sebastiano Padovan, Frank Ghigo, Will Armentrout, Joseph S. Jao, Jon D. Giorgini, Joseph Lazio
Cosmology and Nongalactic Astrophysics · Cross-listed from hep-ph
An axion constraint from the diffuse supernova neutrino background indicated by Super-Kamiokande
Kanji Mori, Tomoya Takiwaki, Kazunori Kohri et al. (+1 more)
Recently, the Super-Kamiokande Collaboration reported an indication of the diffuse
supernova neutrino background (DSNB) with a statistical significance of $2.6\sigma$. Motivated by this possible discovery, we investigate the impact of
axion cooling on the DSNB flux on the basis of long-term
neutrino-radiation hydrodynamic simulations. We compare the observed flux and our models and obtain a $1\sigma$ upper limit $|g_{ap}|<1.3\times10^{-9}$ on the
axion-
proton coupling constant, which is comparable to the conventional limit based on the SN 1987A
neutrino burst. In contrast to the SN 1987A bound, the DSNB constraint does not rely on the properties of a single observed
supernova, because the DSNB represents the cumulative
neutrino emission from a
cosmic population of core-collapse events. More generally, this approach can be applied to other feebly interacting particles that modify protoneutron-
star cooling.
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All authors Kanji Mori, Tomoya Takiwaki, Kazunori Kohri, Masamitsu Mori
Astrophysics of Galaxies
$R_{\rm e}$, or not $R_{\rm e}$: Developing $R_5\equiv R_{-2}$ as a scale radius for galaxy sizes, masses, and mass-to-light ratios
Alister W. Graham
The effective half-light radius $R_{\rm e}$ marks an arbitrary 50-per-cent light boundary, and scaling relations involving such effective radii and their associated surface brightnesses, $\mu_{\rm e}$, systematically (and undesirably) vary as the percentage changes. Here, the projected radius $R_5\equiv R_{-2}$, where the logarithmic slope of the surface-brightness and intensity profile equals $5.00\,\text{mag\,dex}^{-1}$ and $-2$, respectively, and where the luminosity contributed per logarithmic radial interval is maximal, is developed as an alternative. It can be measured non-parametrically or with a parametrized fit. For the Sérsic $R^{1/n}$ family, the exact relation $R_5=(2n/b_n)^n\,R_{\rm e}$ is derived, with $R_5/R_{\rm e}\rightarrow{\rm e}^{1/6}\approx1.181$ as $n\rightarrow\infty$. Reparameterizing the (now $b_n$-free) $R^{1/n}$ model in terms of the observable pair $(R_5,\mu_5)$ removes the non-linear $R_{\rm e}$–$n$ coupling, and because the local slope is $5\,\text{mag\,dex}^{-1}$ at $R_5$, correlated measurement errors in $R_5$ and $\mu_5$ largely cancel when deriving the inferred total magnitude. Additionally, an exact single-integral identity is provided to relate any projected light fraction to the fraction within a sphere of the same radius. The directly observable $R_5$ is shown to be connected, through a weakly $n$-dependent factor to the anisotropy-insensitive intrinsic radius $r_{-3}$, yielding a refined $n$-dependent Wolf-type mass
estimator $M_{-3}$ and spatial mass-to-light ratio $(M_{\rm dyn}/L)_{-3}$. Specifically, $M_{-3}\approx4\,G^{-1}\langle\sigma_{\rm los}^2\rangle\,R_{-2}\approx4.72\,G^{-1}\langle\sigma_{\rm los}^2\rangle\,R_{\rm e}$. Past half-light substitutions in dynamical mass
estimators introduce systematic Sérsic-dependent offsets of 12–18 per~cent in enclosed mass and offsets spanning $>20$ per~cent in the mass-to-light ratio.
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Cosmology and Nongalactic Astrophysics
Infrared Lines from Sterile-Neutrino Transition Magnetic Moments at JWST
Hriditi Howlader, Alekha C. Nayak and Tripurari Srivastava
We investigate infrared line signatures from radiatively decaying sterile-
neutrino dark matter using publicly available JWST/NIRSpec IFU blank-sky observations. The main signal considered is the sterile-to-sterile transition $N_1\to N_2\gamma$, induced by the transition
magnetic dipole coefficient $d_{NN\gamma}$, with $m_1>m_2$. In contrast to ordinary two-
photon decays of
axion-like or Majoron-like particles, the observed
photon energy is not fixed by the full dark matter mass, but by the small mass splitting $\Delta m=m_1-m_2$. Thus, a keV-scale sterile-
neutrino dark matter state can generate an eV-scale infrared
photon line in the JWST band. We construct a $\chi^2$-based line-search analysis using the NIRSpec IFU $\rm F170LP$-$\rm G235M$ blank-sky data toward $\rm GN\text{-}z11$, modelling the smooth continuum with a cubic spline and including the Milky Way
halo decay flux. In the absence of a significant excess, we derive projected limits on $d_{NN\gamma}$ and on the decay width $\Gamma_{N_1\to N_2\gamma}$ for $0.1~{\rm eV}\lesssim\Delta m\lesssim1~{\rm eV}$. For a sterile component saturating the dark matter abundance, the strongest sensitivity reaches $d_{NN\gamma}\lesssim7\times10^{-14}~{\rm GeV}^{-1}$ and $\Gamma_{N_1\to N_2\gamma}\lesssim10^{-25}~{\rm s}^{-1}$. We also include a minimal anomalous-Majoron
benchmark, $\omega\to\gamma\gamma$, obtaining JWST sensitivity to $\lambda_{\omega\gamma\gamma}\sim10^{-11}$-$10^{-9}~{\rm GeV}^{-1}$ for $m_\omega\sim0.6$-$1~{\rm eV}$.
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