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Physics Astrophysics

astro-ph Watch Astrophysics

Tuesday 3 March

Solar and Stellar Astrophysics

Accretion onto the Embedded Protostar L1527 IRS: Insights from JWST NIRSpec and MIRI Observations

W. Blake Drechsler, John J. Tobin, Patrick D. Sheehan et al. (+12 more)

Accretion is the primary driver of protostellar evolution, regulating mass assembly and shaping the physical and chemical environments of young stellar objects. Quantifying accretion in the Class 0 protostellar phase is particularly important, yet remains observationally challenging due to high extinction toward the central protostars. In this paper, we present JWST NIRSpec and MIRI/MRS IFU data towards the Class 0 protostar L1527 IRS. We extract one-dimensional spectra and find emission from atomic and molecular hydrogen, water, OH, and several ionic species. The atomic hydrogen lines, Br$\alpha$, Pf$\alpha$, and Pf$\gamma$ are the most critical to this study since they can be used as accretion diagnostics. The existence of these atomic hydrogen lines viewed in scattered light indicates that accretion is likely occurring magnetospherically rather than through a boundary layer. Moment 0 emission maps show that the hydrogen emission is co-spatial with the scattered light continuum with a strong east-west asymmetry which is not due to outflow shocks. We additionally present moment 0 maps of other detected species and discuss their emission morphology. By primarily analyzing the Br$\alpha$ line, the strongest of our detected atomic hydrogen lines, we characterize the accretion onto L1527 IRS by estimating the accretion luminosity to be $0.4~\text{L}_\odot$ and the accretion rate to be around $1\times10^{-7}~ \text{M}_\odot \text{yr}^{-1}$. We lastly discuss the implications of our results with respect to both non-steady and asymmetric accretion possibly occurring in L1527 IRS.
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All authors W. Blake Drechsler, John J. Tobin, Patrick D. Sheehan, Leslie W. Looney, S. Thomas Megeath, Ewine F. Van Dishoeck, Valentin J. M. Le Gouellec, Thomas P. Green, Logan Francis, R. Devaraj, Martijn Van Gelder, Lee Hartmann, Lukasz Tychoniec, Nuria Calvet, William J. Fischer

Astrophysics of Galaxies

Discovery of a $z\simeq 4.9$ Lyman-$\alpha$ Emitter Protocluster: Wavelength-Dependent Environmental Effects on Galaxy Structure

Ronaldo Laishram, Yusei Koyama, Haruka Kusakabe et al. (+3 more)

We report the discovery of a Lyman-alpha emitter (LAE) protocluster at z = 4.90 in the COSMOS field, comprising four distinct overdensity peaks spanning ~65 x 36 cMpc$^2$, with the primary concentration exhibiting a 4-fold surface density enhancement relative to the field within a 1.5 proper Mpc (pMpc) radius. Using SILVERRUSH narrowband survey data combined with JWST COSMOS-Web imaging, we perform a first systematic rest-frame optical and UV morphological comparison of protocluster versus field LAEs at this redshift using JWST NIRCam rest-frame UV (F150W, ~2540 Angstrom) and optical (F277W, ~4700 Angstrom) imaging. Sersic profile fitting for 16 protocluster members and 23 field LAEs reveals a size difference: protocluster LAEs are $\sim$40% larger in rest-optical (median $R_e = 0.81_{-0.04}^{+0.26}$ kpc vs. $0.58_{-0.04}^{+0.11}$ kpc, $p = 0.041$) with no significant difference in rest-UV ($p = 0.51$) or Sersic index. At fixed stellar mass, protocluster LAEs are offset by $+0.12$~dex ($\simeq$31%) in rest-optical size from the field size-mass relation (68% CI: $[+0.08, +0.21]$; Mann-Whitney $p = 0.033$), with 75% exhibiting positive size residuals compared to 44% of field LAEs. This wavelength-dependent environmental signature suggests that protocluster environments at $z \simeq 5$ preferentially affect extended stellar populations, possibly through tidal interactions, with no significant environmental difference detected in rest-UV sizes, providing observational evidence for environmental influences on the structure of LAEs during the early build-up phase of cosmic star formation.
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All authors Ronaldo Laishram, Yusei Koyama, Haruka Kusakabe, Satoshi Kikuta, Shunta Shimizu, Tadayuki Kodama

Cosmology and Nongalactic Astrophysics

Observational constraints on Luciano-Saridakis entropic cosmology

Matías Leizerovich, Susana J. Landau, Giuseppe Gaetano Luciano et al. (+2 more)

A recently proposed generalized entropy by Luciano and Saridakis extends the standard Boltzmann-Gibbs and Bekenstein-Hawking framework through a microscopically motivated construction involving two independent entropic exponents. When applied within the gravity-thermodynamics correspondence, this entropy leads to a modified cosmological dynamics that can be interpreted as an effective dark energy sector of entropic origin, while recovering $\Lambda$CDM in appropriate limits. In this work, we perform the first observational confrontation of the resulting entropic cosmology at the background level. Focusing on the case $\alpha_\delta=0$, we constrain the model using Cosmic Chronometers, Pantheon$^+$ Type Ia supernovae calibrated with SH0ES, BAO measurements from DESI DR2 and compressed Planck 2018 CMB information. We find that the model yields a statistically robust fit to the combined data sets and can simultaneously satisfy Pantheon$^+$, SH0ES and CMB shift-parameter constraints, unlike $\Lambda$CDM. Although the entropic parameters remain close to their standard values, the $\Lambda$CDM limit is excluded at the $2\sigma$ level within the restricted parameter space considered. These results indicate that the Luciano-Saridakis entropic cosmology offers a viable extension of the standard model with the potential to alleviate the Hubble tension at the background level.
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All authors Matías Leizerovich, Susana J. Landau, Giuseppe Gaetano Luciano, Andreas Papatriantafyllou, Emmanuel N. Saridakis

Earth and Planetary Astrophysics

The multi-wavelength vertical structure of the archetypal $\beta$ Pictoris debris disk

Yinuo Han, Mark C. Wyatt, Marija R. Jankovic et al. (+4 more)

Thermal imaging of debris disks is resolving the vertical height in an increasing number of systems, enabling the use of the vertical structure to decode the dynamical state of the planetary system. In this study, we examine the multi-wavelength structure of the archetypical edge-on debris disk of $\beta$ Pic, extensive imaging of which across mid-infrared to millimeter wavelengths makes it the prime system to study the vertical height across different grain size populations. We non-parametrically modelled the radial profiles and constrained the vertical height at each wavelength while taking into account the vertical warping, finding the disk to be on average 1.5 times thicker vertically in the mid-infrared compared to the millimeter and the scale height to be relatively constant across radius. The decreasing scale height with wavelength is in contrast to predictions from collisional damping, and could be a result of the combined effect of radiation pressure and random collisions. We also show that the disk is warped at millimeter wavelengths and find tentative evidence for clumps in ALMA images which will require follow-up observations to confirm. The millimeter vertical warping is consistent with findings in scattered light and the secular perturbation interpretation due to the inner giant planets, which could also explain the relatively constant apparent scale height across radius, and potentially earlier findings of a non-Gaussian vertical profile which this study confirms.
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All authors Yinuo Han, Mark C. Wyatt, Marija R. Jankovic, Andrew Zhang, William R. F. Dent, A Meredith Hughes, Luca Matrà

Solar and Stellar Astrophysics

A Catalogue of Orbital Periods of Cataclysmic Variables and Candidates from TESS Observations

Meryem K. Dağ, Simone Scaringi, Kieran O'Brien et al. (+21 more)

We present a systematic analysis of 2544 cataclysmic variable systems and related candidates observed by the Transiting Exoplanet Survey Satellite (TESS), with the aim of compiling a comprehensive catalogue of orbital periods. Using 2-minute photometric time-series data, we applied an automated algorithm to generate Lomb-Scargle periodograms and identify the most significant coherent periodic signals, which were subsequently verified through visual inspection. This process yielded a confident sample of 910 sources exhibiting at least one periodic signal, hereafter referred to as the Cataclysmic Variable Confident Catalogue (CCC). For each object, we report the most likely orbital period together with additional periodic features such as spin modulations and/or superhump signals when present. To assess consistency with previously published measurements, we cross-matched the CCC with the Ritter & Kolb catalogue, identifying 300 overlapping systems, of which 215 showed full agreement with the R&K orbital periods, while 39 displayed discrepancies for which the R&K values were revised based on our TESS measurements and supporting evidence from the literature. Overall, the CCC provides a means to validate known orbital periods, propose corrections where necessary, and offer new determinations for systems with previously unknown periods, thereby supporting a more complete and reliable characterisation of the cataclysmic variable population.
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All authors Meryem K. Dağ, Simone Scaringi, Kieran O'Brien, Martina Veresvarska, Nikita Rawat, Yusuke Tampo, Santiago Hernández-Díaz, Colin Littlefield, Krystian Iłkiewicz, Domitilla de Martino, D. A. H. Buckley, Zackery A. Irving, Liliana E. Rivera Sandoval, Wendy Mendoza, Ryan J. Oelkers, Peter Garnavich, Gavin Ramsay, Yuri Cavecchi, Manuel Pichardo Marcano, J. Kára, Elmé Breedt, Axel D. Schwope, Christian Knigge, N. Castro Segura

Astrophysics of Galaxies

Most open clusters follow the radial acceleration relation (RAR) and the baryonic Tully-Fisher relation (BTFR)

Mark D. Huisjes and X. Hernandez

We test whether parsec-scale stellar systems in the Milky Way follow the galactic radial acceleration relation (RAR) or the baryonic TullyFisher relation (BTFR). We analyse 5646 Gaia DR3 open clusters from the Hunt & Reffert catalogue. Observed accelerations are derived from velocity dispersions and characteristic radii, and baryonic accelerations from stellar masses and characterisitc radii. The clusters are placed on the RAR and BTFR planes and compared with Newtonian and MOND expectations. Approximately 90 per cent of open clusters (those with $N_\star \leq 250$) lie close to the RAR, albeit with significant scatter. In a first-of-its-kind test, a smaller fiducial sample is consistent with a best-fitting acceleration scale $g_\dagger \approx 1.2 \times 10^{-10}\ \mathrm{m\,s^{-2}} \pm 0.5$ dex, compatible with canonical MOND values. More massive clusters approach the Newtonian virial expectation. No correlations are found between RAR residuals and galactocentric radii, distance to the Galactic disk midplane, age, or morphology. Tidal effects and unresolved binaries are insufficient to reproduce the observations without fine-tuning. Interpreted within a MOND framework, the alignment of most open clusters with the RAR and BTFR suggests that low-acceleration dynamics operate on parsec scales within the Milky Way. This implies that the Galactic gravitational field is not smooth on these scales and may include regions where the total gravitational acceleration falls below $a_0$, partially mitigating the external field effect, thereby motivating higher-resolution modelling of the Galactic potential and informing other small-scale gravity tests within the Galaxy.
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Instrumentation and Methods for Astrophysics

Matched Filtering for the Canadian Hydrogen Observatory and Radio-Transient Detector Galaxy Search

Hans S. Hopkins, Dustin Lang, Kendrick Smith et al. (+3 more)

We present the spatial part of the point source signal extraction strategy for the upcoming CHORD galaxy survey. CHORD, the Canadian Hydrogen Observatory and Radio-transient Detector, is an under-construction drift-scanning compact interferometric radio telescope. CHORD comprises 512 six meter dishes and observes in the 300 to 1500 MHz frequency range. One of its science goals is producing a catalogue of galaxies detected by the neutral hydrogen (HI) 21 cm emission line. CHORD's highly redundant dish layout creates the problem of spatial aliasing, the effect where the same signal could be feasibly produced from sources at multiple locations on the sky. The search will be done with a matched filter in the visibility plane. This paper presents the search strategy and a prediction tool that can quickly estimate the matched filter response at a given sky position, allowing a prediction of alias locations and severity. This tool confirms that although aliases are impossible to distinguish in a single snapshot, they become possible to distinguish when combining data over a period of time. It predicts that aliases will be harder to distinguish for observations closer to the celestial equator, but that scanning with offset adjacent strips can remove this degeneracy. It predicts that the optimal strategy for a single offset to disambiguate aliases is to re-point the array in declination by about two degrees. A future paper will combine these findings with realistic noise estimates and galaxy population statistics to make forecasts of the population of galaxies that CHORD will detect.
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All authors Hans S. Hopkins, Dustin Lang, Kendrick Smith, Kristine Spekkens, Simon Foreman, Akanksha Bij

Instrumentation and Methods for Astrophysics

Measuring the Column Dependence of Read Noise in ACS/WFC Bias Frames

Alyssa M. Guzman and Meaghan C. McDonald

The noise in bias frames for all four readout amplifiers in the Advanced Camera for Surveys (ACS) Wide Field Channel (WFC) is dependent on row number. This is because dark current accumulated during readout increases across the detector, influencing and increasing the read noise as a function of row number. In this report, we investigate bias frames taken with the ACS/WFC to explore the column dependence of read noise for each of the amplifiers for different anneal periods. Analyzing the data, we find that there is no column dependence of read noise and that the read noise values for the physical pre-scans are approximately 0.5 e$^-$ lower than in the science arrays because there is no readout dark accumulated in this area. We further investigate 1) the evolution of read noise over an anneal period, 2) a linear decrease in read noise within the initial columns per amplifier, and 3) pixels in elevated read noise columns. We conclude that 1) there is no visual trend of read noise over an anneal period, 2) amplifiers A and C have an initial linear decrease of read noise in the science arrays, and 3) masking unstable hot pixels in a column will decrease its read noise values.
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Earth and Planetary Astrophysics · Cross-listed from eess.SY

Multidisciplinary Design Optimization of a Low-Thrust Asteroid Orbit Insertion Using Electric Propulsion

Yacob Medhin, Tushar Sial and Simone Servadio

Low-thrust electric propulsion missions are often designed under simplifying assumptions such as constant thrust or fixed specific impulse, neglecting the strong coupling between trajectory dynamics, spacecraft power availability, and propulsion performance. In deep-space environments with reduced solar irradiance, these assumptions can lead to suboptimal or infeasible designs, underscoring the need to simultaneously optimize the trajectory and power subsystem. This paper presents a multidisciplinary design optimization (MDO) framework for the simultaneous design of low-thrust trajectories and spacecraft power systems, with explicit coupling to electric propulsion performance. The framework incorporates a high-fidelity variable-specific impulse model of the SPT-140 Hall thruster, in which thrust and efficiency are directly constrained by time-varying solar power availability and solar array degradation, rather than treated as fixed parameters. The coupled problem is posed as a time-optimal control problem and addressed using a framework built on top of OpenMDAO and Dymos toolchains, where Dymos employs a collocation-based direct-transcription approach for trajectory optimization. OpenMDAO provides accurate analytic partial derivatives, enabling efficient gradient-based optimization. A Fast Fourier Series shape-based method is used to generate dynamically feasible initial guess trajectories, and the resulting nonlinear programming problem is solved using IPOPT. The proposed framework is demonstrated through a low-thrust orbit insertion scenario around asteroid 16-Psyche, a regime in which reduced solar irradiance makes power-aware trajectory design particularly critical. Simulation results demonstrate the framework's ability to capture key power-propulsion-trajectory trade-offs, highlighting the importance of integrated power optimization for realistic electric propulsion mission design.
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Cosmology and Nongalactic Astrophysics

Background dynamics and observational constraints of flat and non-flat $\Lambda(t)$CDM models from $H(z)$ and DESI DR2 BAO measurements

Olga Avsajanishvili

In this work, we present comprehensive observational constraints on the time-varying vacuum Lambda(t)CDM cosmology using the latest baryon acoustic oscillation (BAO) data from Dark Energy Spectroscopic Instrument (DESI) Data Release 2 measurements in combination with cosmic chronometer H(z) data. We explicitly quantify the impact of vacuum dynamics on the expansion history, the total effective equation of state parameter of the unified cosmic fluid, the effective dark energy equation of state parameter, and the deceleration parameter in the spatially flat Lambda(t)CDM model. We perform a full Markov Chain Monte Carlo (MCMC) analysis and statistical model comparison, providing a consistent assessment of the Lambda(t)CDM model relative to the standard LambdaCDM framework. Our results demonstrate that H(z) and BAO observations strongly constrain deviations from the LambdaCDM model, driving the vacuum dynamics parameter alpha toward zero, while significantly reducing parameter degeneracies and alleviating the Hubble tension.
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High Energy Astrophysical Phenomena

Discovery of Strong Energy-Dependent X-ray Polarization in the Intermediate State of GS 1354-64

Swati Ravi, Lorenzo Marra, James F. Steiner et al. (+20 more)

We report the discovery of significant X-ray polarization from the dynamically confirmed black hole X-ray binary (BHXB) GS 1354-64 during its 2025-2026 outburst, obtained with the Imaging X-ray Polarimetry Explorer (IXPE). The observation, obtained shortly after a bright X-ray flare, captures the source in an intermediate state following a stalled (failed) state transition. We discover significant 2-8 keV polarization at the ~4% level with high statistical support–14-sigma significance from frequentist analysis and log Bayes Factor 283+/-1 in a Bayesian framework–measuring PD 4.0+/-0.2% and PA-1+/-2 degrees (90% credible interval). The PD exhibits a statistically significant increasing trend with energy–the strongest such increase yet observed by IXPE in a BHXB–going from 2.1+/-0.3% in the 2-3 keV band to 11+/-3% in the 6.5-7 keV band, while the PA appears stable across both energy and time to within statistical uncertainties. Timing analysis of the IXPE data reveals a ~5 Hz Type-C quasi-periodic oscillation. IXPE + NuSTAR spectropolarimetric modeling suggests that the data can be described by polarized thermal disk and Comptonized components with PAs differing by ~90 degrees, or by a dominant Comptonized polarized component whose effective PD increases across the IXPE bandpass–the inferred component-level polarization levels are therefore model-dependent. In either picture, GS 1354-64 retains a strong coronal component during the transitional period observed by IXPE. These results illustrate how X-ray polarimetry can provide a sensitive diagnostic of the accretion state and geometry in black hole X-ray binary accretion flows, exploring a liminal phase at the cusp of state transition.
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All authors Swati Ravi, Lorenzo Marra, James F. Steiner, Guglielmo Mastroserio, Mason Ng, Joey Neilsen, Herman L. Marshall, Fiamma Capitanio, Sudeb Ranjan Datta, Elise Egron, Javier A. Garcia, Adam Ingram, Philip Kaaret, Ole Koenig, Honghui Liu, Romana Mikusincova, Edward J. R. Nathan, P.-O. Petrucci, Jakub Podgorny, Chiara Salvaggio, Jiri Svoboda, Alexandra Veledina, Yuexin Zhang

Solar and Stellar Astrophysics

The Effect of Different Methods for Accounting for $\alpha$-enhancement on the Asteroseismic Modeling of Metal-Poor Stars

Christopher J. Lindsay, J. M. Joel Ong, Sarbani Basu et al. (+2 more)

Constraining stellar models using asteroseismic and spectroscopic observations is a powerful method for precisely determining the fundamental properties of stars in different kinematic components of our galaxy. We use spectroscopy and individual oscillation mode frequencies to perform a homogeneous modeling study of eight evolved metal-poor stars enhanced in $\alpha$-elements. We compare a full treatment of $\alpha$-enhancement against an ad hoc correction to the total metallicity and show that the stellar properties inferred from asteroseismic modeling using both sets of models agree with each other. Additionally, we find that the uncertainties on stellar parameters derived from the both $\alpha$-enhanced modeling methods are comparable. This is in qualitative disagreement with existing works showing red-giant ages constrained by only the global asteroseismic parameters to depend strongly on the opacities and abundances assumed in 1D modeling. We also show that the observed frequency of maximum oscillation power ($\nu_{\text{max}}$) is larger than the value predicted from applying the $\nu_{\text{max}}$ scaling relation to the masses, radii, and temperatures inferred from the detailed modeling. This discrepancy is pronounced at low metallicities, consistent with recent findings indicating a breakdown of the $\nu_{\text{max}}$ scaling relation for metal-poor stars. Understanding the extent to which the $\nu_{\text{max}}$ scaling relation fails for low-metallicity solar-like oscillators through detailed modeling will enable more accurate mass and age determinations for hundreds of giant stars in the Galactic Halo for which only global asteroseismic parameters are available.
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All authors Christopher J. Lindsay, J. M. Joel Ong, Sarbani Basu, Samuel Grunblatt, Marc Hon

Instrumentation and Methods for Astrophysics

Updating the Sensitivity Curves of the STIS Echelles (Post-SM4)

Svea Hernandez, TalaWanda Monroe and Joleen K. Carlberg

The STIS team re-derived on-orbit sensitivity curves for the echelle modes for post-servicing mission 4 observations using the standard DA white dwarf G 191-B2B. These new updates relied on the recent CALSPECv11 models, which introduced improvements in the fluxes of the primary standard stars of the order of~1-3% depending on the wavelength of interest. As part of this effort, the team also released new blaze shift coefficients and echelle ripple tables. We present a detailed description of the procedures followed in the derivation of these new throughputs and the accompanying updates.
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Cosmology and Nongalactic Astrophysics

Illuminating the dark universe in the multi-messenger era

Philippe Brax, Anne-Christine Davis, Md Riajul Haque et al. (+8 more)

The precision era of multi-messenger astronomy, together with modern astrophysical, cosmological, and gravitational wave observations, increasingly points toward the existence of a “dark" sector that cannot be explained within the framework of the Standard Model of particle physics and General Relativity. In this review, we explore extensions of standard physics and examine how observational data can be used to probe new particles and interactions. We consider a wide range of scales, from Solar System tests to galactic and cosmological observations, and investigate both conventional dark matter candidates, such as weakly interacting massive particles, and alternative scenarios including ultralight fields and primordial black holes. We discuss constraints derived from compact objects such as neutron stars, black holes, pulsars, and magnetars observations as well as from high-energy astrophysical phenomena. In addition, we analyze extensions of General Relativity involving additional scalar fields and their impact on gravitational wave signals and stochastic backgrounds from primordial black holes. We also study the capture and accumulation of dark matter in compact objects, which can alter properties such as mass, radius, and tidal deformability, and consider scenarios in which dark matter decays into Standard Model particles. While current observations already place significant limits on dark matter and modified-gravity models, upcoming experiments and observatories are expected to further probe or discover such new physics by improving constraints on particle masses and interaction strengths.
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All authors Philippe Brax, Anne-Christine Davis, Md Riajul Haque, Cédric Jockel, Gaetano Lambiase, Michiru Uwabo-Niibo, Mohsen Khodadi, Tanmay Kumar Poddar, Laura Sagunski, Luca Visinelli, Jun Zhang

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

New Thermal-Relic Targets for sub-GeV Dark Matter Direct Detection

Xu Han and Gordan Krnjaic

Dark matter direct detection experiments involving electron recoils are beginning to test highly-predictive, thermal-relic milestones for sub-GeV dark matter models. Due to the Lee-Weinberg bound, thermal dark matter candidates in this mass range necessarily require comparably-light mediator particles to achieve a suitably large annihilation cross section. Here we present new thermal-relic milestones for sub-GeV dark matter candidates that couple to vector mediators. In these models, the mediators are massive gauge bosons of anomaly-free abelian extensions to the Standard Model, including the dark photon, gauged $L_i - L_j, B-L$, and $B-3L_i$ models, where $B$ is the baryon number, $L$ is the lepton number, and $i,j$ index the lepton families. Since the same interactions that govern cosmological production also govern electron scattering, the targets we present are firmly predictive and allow for these models to be robustly discovered or falsified. Furthermore, since the mediators we study exhaust the minimal anomaly-free U(1) extensions to the Standard Model, our results offer a complete list of predictive milestones for sub-GeV dark matter coupled to vector mediators.
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Cosmology and Nongalactic Astrophysics

The BAO scale – how standard is the standard ruler?

Francisco Asensio-Rivera, Nils Schöneberg, Héctor Gil-Marín et al. (+1 more)

Analyses of baryon acoustic oscillations (BAO) commonly employ template-based methods to extract compressed parameters from the clustering of dark-matter tracers, which are then interpreted in terms of ratios of the sound-horizon scale and cosmological distances relative to a fiducial cosmology. A small mismatch between the sound-horizon scale derived from the standard analytic formulation (integral over the sound speed) and the effective scale imprinted in clustered matter can, however, introduce a systematic bias in cosmological inference. We extend previous work to a broader class of cosmological models, quantify this bias for surveys with DESI-like precision, and propose strategies to correct for the effect. We find that the induced bias becomes a significant fraction of the statistical uncertainty for deviations from the fiducial cosmology, at the level of $|\Delta \Omega_m| = 0.03$ and $|\Delta N_\mathrm{eff}| = 0.3$, and for very precise data corresponding to a forecasted Year-5 DESI survey (or other stage IV dark energy galaxy surveys). We present several ways to correct for this effect, suitable for a variety of applications. We therefore recommend that analyses exploring such parameter regimes either apply the proposed corrections or include an appropriate systematic error budget.
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All authors Francisco Asensio-Rivera, Nils Schöneberg, Héctor Gil-Marín, Licia Verde

Earth and Planetary Astrophysics

Spiral formation caused by late infall onto protoplanetary disks

L.-A. Hühn, C. N. Kimmig and C. P. Dullemond

The classical picture that planet formation occurs in protoplanetary disks that are isolated from their environment is undergoing a major shift toward a more connected picture. An increasing amount of evolved disks are found to be actively interacting with their environment, often showing various types of spiral structures. In this work, we aim to investigate if these spirals can be a direct result of ongoing late infall using the grid-based 3D hydrodynamics code FARGO3D. We perform a detailed analysis of the spiral properties and appearance in scattered light and CO line emission using the radiative transfer code RADMC3D. In scattered light, we find both well-defined spirals with few arms (m=2) and more flocculent structures: The gradual accretion of gas remnants after a major accretion event has the most success in the former, whereas active accretion via streamers favors the latter. The m=2 spirals we find have a very low pattern speed, making them easily discernible from spirals caused by a perturber. We also find spiral patterns in the $^{12}$CO residual motions, but their morphology does not match the one found in scattered light. The disk perturbations are strongest in the upper layers (z>4H), which is reflected by the reduced amplitude of the residual motions in the more optically thin $^{13}$CO emission. Moreover, we find that the formation of m=2 spirals is not promoted in disks with lower mass, despite being more susceptible to deeper kinematic perturbations. While the late-infall streamers impact planet formation directly through the delivery of fresh material, we show that the midplane remains unperturbed unless the infalling mass is of the same order of magnitude as the disk mass. Planet formation can therefore only be impacted by late infall through secondary mechanisms that lead to dust trapping or the generation of turbulence starting from surface-level perturbations.
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Cosmology and Nongalactic Astrophysics

Cosmology with the line-of-sight shear of strong gravitational lenses

Pierre Fleury, Daniel Johnson, Théo Duboscq et al. (+2 more)

Stage-IV photometric galaxy surveys are designed to measure the position and shapes of billions of galaxies. Their aim is to characterise the large-scale distribution of matter in the Universe using galaxy clustering and weak gravitational lensing. As a byproduct, stage-IV surveys are expected to detect more than a hundred thousand strong gravitational lenses. In this article, we propose the use of weak-lensing perturbations to strong lenses, specifically their line-of-sight (LOS) shear, as a cosmological probe. This new observable allows us to define three new correlation functions: the LOS shear with itself, with galaxy positions, and with galaxy shapes, thereby promoting the standard $3\times 2$pt correlation method to a $6\times 2$pt scheme. We design estimators for these new correlation functions and determine their expectation values as a function of the matter power spectrum. We then derive the analytical expression for the full covariance matrix of the $6\times 2$pt correlation scheme. Considering various scenarios for the stage-IV strong-lensing samples, we demonstrate that the cosmological information carried by the LOS shear of strong lenses will be detectable with a very high signal-to-noise ratio, even in the most pessimistic of cases. Strong lenses are thus extremely promising cosmological probes, whose synergy with galaxy positions and shapes should also contribute to mitigating systematics in stage-IV surveys.
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All authors Pierre Fleury, Daniel Johnson, Théo Duboscq, Natalie B. Hogg, Julien Larena

Cosmology and Nongalactic Astrophysics

CHEX-MATE: Are we getting cluster thermodynamics right?

R. Seppi, D. Eckert, E. Rasia et al. (+19 more)

Galaxy clusters offer powerful insights into the large-scale structure of the Universe and the physics of baryons in hot state. Their scientific exploitation, however, hinges on our ability to accurately measure key thermodynamic properties. In this work, we aim to assess the reliability of current analysis techniques in reconstructing these properties, with particular focus on samples similar to those observed in the Cluster HEritage project with XMM-Newton (CHEX-MATE). We develop a suite of dedicated end-to-end simulations of CHEX-MATE-like clusters selected from large scale hydrodynamical simulations, and processed through a newly developed realistic XMM-Newton simulator. We apply a full X-ray data analysis pipeline to the mock datasets, including imaging, spectral fitting, and profile reconstruction. The gas density profiles can be robustly recovered across a wide radial range, when using azimuthal mean surface brightness profiles. Our reconstruction techniques are able to reproduce the intrinsic density profile with the correct scatter, with deviations of at most 10% between 0.1 and 1xR500c. The gas mass is reconstructed with better than 1% accuracy. Accurate measurement of temperature profiles is more challenging and possibly subject to biases, particularly in the presence of azimuthal variations and multi-temperature gas along the line of sight, which dominate over projection effects. Our results highlight the need for caution in interpreting cluster temperature measurements and underscore the value of tailored mock observations for understanding observational systematics. These findings also suggest that biases in X-ray temperature measurements may alter the interpretation of the thermodynamical state of the intra-cluster medium, an outlook particularly relevant in light of recent low velocity measurements from the XRISM mission.
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All authors R. Seppi, D. Eckert, E. Rasia, S. T. Kay, K. Dolag, V. Biffi, Y. E. Bahar, H. Bourdin, F. De Luca, M. De Petris, S. Ettori, M. Gaspari, F. Gastaldello, V. Ghirardini, L. Lovisari, P. Mazzotta, G. W. Pratt, E. Pointecouteau, M. Rossetti, J. Sayers, M. Sereno, G. Yepes

Astrophysics of Galaxies

Tracing the AGN-Merger Connection: insights from cosmological simulations and JWST mock observations

Hannah Jhee, Ena Choi, Rachel S. Somerville et al. (+6 more)

Galaxy mergers have long been proposed as a mechanism for funneling gas toward galactic centres, potentially triggering accretion onto supermassive black holes (SMBHs) and igniting active galactic nuclei (AGN). While simulations often support this scenario, observational studies have yielded conflicting results regarding the AGN-merger connection. In this study, we analyze 31 galaxies from cosmological zoom-in simulations spanning redshifts $0.5 < z < 3$. We identify mergers using detailed merger trees based on six-dimensional dark matter particle information and identify AGN activity through SMBH accretion histories. To bridge the gap between simulations and observations, we generate mock JWST-like images and extract non-parametric morphological parameters. Employing a $k$-nearest neighbours (KNN) classifier in a five-dimensional space (four morphological parameters and redshift), we identify mergers in the mock-observed dataset. Our analysis reveals a statistically significant enhancement of AGN activity in merging systems, particularly at lower redshifts ($0.5 < z < 0.9$), where central gas reservoirs are more depleted. This supports the view that mergers contribute more significantly to AGN triggering in environments with low internal gas reservoirs, while their impact may be less pronounced in gas-rich systems. However, when relying solely on morphological classifications from mock observations, the observed AGN-merger connection weakens, especially at higher redshifts. This underscores the challenges in detecting merger-induced AGN activity observationally and highlights the importance of combining simulations with realistic mock observations to fully understand the AGN-merger relationship.
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All authors Hannah Jhee, Ena Choi, Rachel S. Somerville, Dale D. Kocevski, Michaela Hirschmann, Thorsten Naab, Desika Narayanan, Intae Jung, Juhan Kim

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

The COSMIC WISPers White Paper: The physics case for Weakly Interacting Slim Particles

Ariel Arza, Deniz Aybas, Shyam Balaji et al. (+124 more)

Axions and other very weakly interacting slim particles (WISPs), with masses below 1 GeV, arise naturally in many extensions of the Standard Model of particle physics. In particular, they could offer a new framework to explain the nature of dark matter and may help address a range of puzzling observations in astrophysics and particle physics. This review provides an overview of ongoing WISP searches and outlines the prospects for the next decade, spanning their theoretical motivation, indirect signatures in astrophysical observations, and dedicated laboratory experiments. It is based on the work carried on by the EU-funded COST Action “Cosmic WISPers in the Dark Universe: Theory, astrophysics, and experiments” (CA21106, https://www.cost.eu/actions/CA21106). This network plays a key role in coordinating and supporting WISP searches across Europe, while also contributing to the development of a roadmap aimed at securing European leadership in this research area. It is emphasized that Europe is currently pursuing a rich, diverse, and cost-effective experimental program, with the potential to deliver one or more transformative discoveries.
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All authors Ariel Arza, Deniz Aybas, Shyam Balaji, Reuven Balkin, Kai Bartnick, Charles F. A. Baynham, Itay M. Bloch, Claudio Bonati, Dmitry Budker, Clare Burrage, Malte Buschmann, Francesca Calore, Francisco R. Candón, Pierluca Carenza, Serkant Ali Cetin, Francesca Chadha-Day, Sreemanti Chakraborti, Kiwoon Choi, Michele Cicoli, Lei Cong, Joseph P. Conlon, Florin Lucian Constantin, José Correia, Claudia De Dominicis, Arturo de Giorgi, Pedro De la Torre Luque, Javier De Miguel, Francesco D'Eramo, Alejandro Díaz-Morcillo, Patricia Diego-Palazuelos, David Díez-Ibáñez, Luca Di Luzio, Amelia Drew, Babette Döbrich, Christopher Eckner, Aldo Ejlli, Sebastian A. R. Ellis, Angelo Esposito, Elisa Ferreira, Nahuel Ferreiro Iachellini, Damiano F. G. Fiorillo, Matteo Galaverni, Michele Gallinaro, Camilo García-Cely, Silvia Gasparotto, Claudio Gatti, Daniel Gavilan-Martin, Maurizio Giannotti, Benito Gimeno, Marco Gorghetto, Giovanni Grilli di Cortona, Jordan Gué, Gerard Higgins, Dieter Horns, Mathieu Kaltschmidt, Marin Karuza, Venelin Kozhuharov, Stepan Kunc, Francesca Lecce, Alessandro Lella, Axel Lindner, Maria Paola Lombardo, Giuseppe Lucente, Olympia Maliaka, Cristina Margalejo, Marios Maroudas, Luca Marsicano, Luca Merlo, Alessandro Mirizzi, Vasiliki A. Mitsou, Guido Mueller, Kai Murai, Toshiya Namikawa, Fumihiro Naokawa, Le Hoang Nguyen, Ciaran O'Hare, Tomas O'Shea, Ippei Obata, Ali Övgün, Francisco Gil Pedro, Giovanni Pierobon, Tanmay Kumar Poddar, Josef Pradler, Pierre Pugnat, Beyhan Puliçe, Raquel Quishpe, Georg G. Raffelt, Maria Ramos, Wolfram Ratzinger, Marco Regis, Mario Reig, Sophie Renner, Alessio Rettaroli, Nicole Righi, Andreas Ringwald, Laura R. Roberts, Keir K. Rogers, Qazal Rokn, Ophir M. Ruimi, Jaime Ruz, Kenichi Saikawa, Marco Scalisi, Andreas Schachner, Joern Schaffran, Kristof Schmieden, Matthias Schott, Javi Serra, Anton Sokolov, Paolo Spagnolo, Konstantin Springmann, Michael Staelens, Stefan Stelzl, Oscar Straniero, Marco Taoso, Elisa Todarello, Claudio Toni, Lorenzo Ubaldi, Federico Urban, Rodrigo Vicente, Luca Visinelli, Edoardo Vitagliano, Julia K. Vogel, Andreas Weiler, Samuel J. Witte, Michael Wurm, Wen Yin, Konstantin Zioutas

Astrophysics of Galaxies

The kinematic imprinting of environmental quenching in $z<0.2$ galaxies

Natan de Isídio, P. Popesso, Y. Bahé et al. (+9 more)

We present the first systematic census of quenching mechanisms using kinematic asymmetries in a large sample of $\sim$6,700 galaxies from the MaNGA survey, providing a unified view of what halts star formation in the local Universe ($z<0.2$). We quantify stellar and nebular gas disturbances through the higher-order terms of a Fourier series expansion. These asymmetries serve as powerful diagnostics, as different quenching mechanisms leave distinct kinematic signatures on gas and stars. Our analysis reveals that the most effective quenching pathways leave minimal kinematic imprints by the time galaxies are fully quenched. This "kinematic regularity" points toward slow-acting processes (>3 Gyr) such as starvation and maintenance feedback. A striking finding emerges from our mass-matched analysis: quenched symmetric satellites are significantly more compact than their asymmetric counterparts ($3.4\sigma$), a trend that is even more pronounced for symmetric centrals ($12.3\sigma$). Our results suggest that environment drives the dominant satellite quenching pathway through rapid gas stripping followed by long-term starvation. These compact, kinematically undisturbed satellites (the most representative case within our sample) have undergone intense gas stripping and central compaction, creating bulge-like structures with old, metal-rich stellar populations. Combined with halo gas cut-off and the prevention of cosmological accretion due to starvation, this creates an irreversible quenching path. Conversely, the larger sizes of disturbed, quenched centrals are consistent with merger-driven growth. Internal processes, likely driven by the AGN cycle over 1-3 Gyr that prevents hot halo gas cooling, sustain quenching maintenance in this population. The absence of asymmetric satellites in the star-forming regime suggests environmental quenching operates without significant kinematic perturbation.
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All authors Natan de Isídio, P. Popesso, Y. Bahé, B. Vulcani, V. Toptun, I. Marini, B. Poggianti, V. Biffi, F. Belfiore, C. Lagos, K. Dolag, D. Mazengo

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

The effects of non Bunch-Davies initial conditions on gravitationally produced relics

Enrico Bertuzzo, Gabriel M. Salla and Andrea Tesi

Typical gravitational production of relics from amplification of inflationary perturbations assumes Bunch-Davies initial conditions, i.e. a vacuum with initially no particles. In this paper we investigate the impact of non Bunch-Davies initial conditions to the final abundance of relics, with particular attention to the parameter space where the total dark matter abundance is reproduced. We present a general framework for any initial condition, through which we show their non-trivial effect on both spectrum and late-time abundance. We argue that for particles whose source of conformal symmetry breaking comes only from a mass term (spin-1/2 fermions and conformally coupled scalars), the choice of initial conditions has little impact on the mass range relevant to dark matter. For other particles, e.g. the longitudinal mode of spin-1, we see a large deviation from the standard computation. We exemplify and quantify our results with an initial thermal state and a two-stage inflation scenario, highlighting that the total dark matter can be obtained for a wide range of masses.
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Astrophysics of Galaxies

Mature but Still Growing: JWST Detection of the Earliest Intracluster Light at z ~ 2

Hyungjin Joo, M. James Jee, Kyle Finner et al. (+6 more)

We present a JWST analysis of intracluster light (ICL) in XLSSC 122 at z = 1.98, currently the most distant known strong lensing galaxy cluster with an evolved member population. Using deep JWST imaging complemented by HST data and careful control of systematics, we robustly detect diffuse emission extending to several hundred kpc from the brightest cluster galaxy (BCG) down to about 29 mag arcsec^-2. Multi component PSF convolved Sersic modeling separates the surface brightness profiles into three components: a BCG core, a BCG envelope, and an ICL component, with stable Sersic indices across wavelengths. Nearly flat color profiles indicate minimal radial variation in the stellar populations of the BCG envelope and the ICL. The median ICL fraction measured across seven bands is about 17 percent, demonstrating that the buildup of intracluster stars in massive halos was already well underway by z about 2. The ICL fraction peaks near 5000 Angstrom in the rest frame, resembling the behavior observed in dynamically active clusters. We also detect a southern excess of ICL relative to the best fit Sersic model and quantify it using wavelet based modeling, providing additional support that this system is dynamically active. The BCG + ICL light distribution and strong lensing mass map show strong morphological agreement within about 100 kpc. These findings establish the ICL as an early forming and dynamically informative component of massive halos.
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All authors Hyungjin Joo, M. James Jee, Kyle Finner, Zachary P. Scofield, Sangjun Cha, Jinhyub Kim, Ranga-Ram Chary, Andreas Faisst, Bomee Lee

Solar and Stellar Astrophysics

Benchmarking pre-main sequence stellar evolutionary tracks using disk-based dynamical stellar masses

Luigi Zallio, Miguel Vioque, Sean M. Andrews et al. (+14 more)

Stellar masses are a fundamental property to understand models of pre-main sequence evolution, but their values derived from Hertzsprung-Russell (HR) diagrams are strongly model dependent. We benchmark pre-main sequence stellar evolutionary tracks using stellar masses dynamically estimated by fitting a parametric model to ALMA observations of the $^{12}$CO $(J=3-2)$ line transition emitted by the disks orbiting 20 sources in the old ($4-14$ Myr) Upper Scorpius star forming region. We derive stellar masses from HR diagram fitting for ten different stellar evolutionary models, which we then compare with their stellar dynamical masses for comparison in the stellar mass range $0.1-1.3 \> M_\odot$. Models with a moderate-to-low fraction of cold stellar spots ($f=17\%$) most accurately reproduce the dynamical stellar masses ($100\%$ of the targets agree within $\pm1\sigma$). While a higher spot coverage ($f=34\%$) provides similar stellar mass predictions similar to magnetic equipartition models, larger fractions ($f\geq51\%$) significantly disagree with dynamical masses. Magnetic equipartition models overestimate stellar masses up to a factor $\sim20\%$, whereas non-magnetic models underestimate them up to $\sim12\%$. For some models, there is evidence that the stellar mass discrepancies are anticorrelated with dynamical stellar masses. When stellar dynamical mass priors are considered in HR diagram fitting, the median age of a single source can change up to $\sim25\%$, while the median ages inferred across different tracks become consistent, with the age scatter decreasing by $\gtrsim77\%$. These results provide strong empirical constraints for testing and developing evolutionary models of pre-main sequence stars.
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All authors Luigi Zallio, Miguel Vioque, Sean M. Andrews, Aaron Empey, Giovanni P. Rosotti, Anna Miotello, Carlo F. Manara, John M. Carpenter, Dingshan Deng, Nicolás T. Kurtovic, Charles J. Law, Cristiano Longarini, Teresa Paneque-Carreno, Richard Teague, Marion Villenave, Hsi-Wei Yen, Francesco Zagaria

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

Lower bound on the radii of black-hole shadows

Shahar Hod

The non-linearly coupled Einstein-matter field equations predict the existence of shadows with well-defined boundaries around black holes. We prove that, in spherically symmetric hairy black-hole spacetimes whose matter fields satisfy the weak energy condition, the radii of these shadows are bounded from below by the dimensionless relation $r_{\text{sh}}/r_{\text{H}}\geq 3\sqrt{3}/2$, where $r_{\text{H}}$ is the horizon radius of the central hairy black hole. The characteristic shadow of the (bald) Schwarzschild black-hole spacetime saturates the analytically derived lower bound.
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High Energy Astrophysical Phenomena · Cross-listed from gr-qc

New symmetry for the imperfect fluid

Alcides Garat

We will address the existence of a new symmetry for an imperfect fluid by introducing local four-velocity gauge-like transformations for the case when there is vorticity. A similar tetrad formulation as to the Einstein-Maxwell spacetimes formalism presented in previous manuscripts will be developed in this manuscript for the imperfect fluids. The four-velocity curl and the metric tensor will be invariant under these kind of four-velocity gauge-like local transformations. While the Einstein-Maxwell stress-energy tensor is locally gauge invariant under electromagnetic gauge transformations, the perfect fluid stress-energy tensor will not be invariant under four-velocity gauge-like local transformations. We will dedicate our analysis to the imperfect fluid stress-energy tensor that will be invariant under local four-velocity gauge-like transformations when additional transformations are introduced for several variables included in the stress-energy tensor itself. We will also pay special attention to the construction of a vorticity stress-energy tensor invariant under local four-velocity gauge-like transformations. An application on neutron stars will be developed in order to show the simplifications brought about by these new tetrads.
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Instrumentation and Methods for Astrophysics · Cross-listed from physics.data-an

Structured generalized sliced Wasserstein distance for keV X-ray polarization analysis with Gas Pixel Detector

Pengcheng Ai, Hongtao Qin, Xiangming Sun et al. (+3 more)

Because of the special angular distribution of excited electrons by the photoelectric effect, the Gas Pixel Detector (GPD) is effective in measuring keV X-ray polarization of astrophysical events (e.g. gamma-ray bursts), by capturing ionization tracks of excited electrons as polarized images. Traditionally, the emission angles of photoelectrons are extracted from polarized images first, and statistics are then performed on these angles to infer the polarization direction and intensity. However, observation with the wide field of view requires the incident angle of X-rays not directly attainable through the traditional analysis process. In this paper, we propose using the generalized sliced Wasserstein (GSW) distance, projected by neural networks with random weights, as a completely data-driven approach to analyze X-ray polarization based on two-dimensional polarized images. We find the structures of the randomized neural networks matter when focusing on different aspects of the polarized images, and take advantage of the discrimination abilities by different neural network structures. The proposed method, named the structured GSW distance, successfully distinguishes polarized images with different configurations of incident angles and polarization directions. Furthermore, we build a simplified statistical model based on the von Mises distribution and the circular Wasserstein distance and compare the model against the proposed method, showing their high consistency. The computational method reported in this paper may benefit GPD-based polarimetry in astroparticle experiments and also pattern analysis on raw data from pixel detectors.
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All authors Pengcheng Ai, Hongtao Qin, Xiangming Sun, Dong Wang, Huanbo Feng, Hongbang Liu

Cosmology and Nongalactic Astrophysics

Neutrino mass limits and decaying dark matter: background evolution versus perturbations

Thomas Montandon, Vivian Poulin, Thomas Rink et al. (+1 more)

We revisit cosmological neutrino mass bounds when a fraction of dark matter is allowed to decay to massless dark radiation. By compensating the late-time increase in the matter density induced by neutrinos becoming non-relativistic, decaying dark matter (DDM) can render datasets solely sensitive to the background density effectively insensitive to neutrino masses. Using data from baryonic acoustic oscillations (BAO) and Type Ia supernovae together with a distance prior from the cosmic microwave background (CMB), we find that neutrino masses as large as ${\cal O}(1\,\mathrm{eV})$ are allowed without degrading the fit. Moreover, the combination of BAO data with the CMB distance prior yields a preference for a non-zero DDM fraction, and alleviates the need for dynamical dark energy with phantom crossing. However, the degeneracy introduced by DDM is decisively broken once perturbation observables are included. Incorporating the full $\textit{Planck}$ CMB likelihood, and in particular CMB lensing, restores strong constraints on the neutrino mass in the DDM scenario, $\sum m_\nu \lesssim 0.079\,\mathrm{eV}$. In contrast, neutrino mass constraints in a smooth dark energy model described by the Chevallier-Polarski-Linder parametrization become merely $\sim 25\%$ stronger compared to background-only analyses. Our results highlight the essential role of structure-growth measurements in assessing extensions of the dark sector and to obtain robust cosmological neutrino mass bounds.
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All authors Thomas Montandon, Vivian Poulin, Thomas Rink, Thomas Schwetz

Instrumentation and Methods for Astrophysics · Cross-listed from physics.flu-dyn

A More Rigorous Test Problem For Viscous Hydrodynamics Codes

Alexander J. Dittmann and Geoffrey Ryan

We advocate for a more stringent test problem for codes that aim to solve the equations of viscous hydrodynamics. Specifically, we discuss a nonuniform-density version of the common (uniform-density) Gaussian velocity shear test, where density gradients transverse to the direction of velocity shear cause the velocity profile to drift over time. By employing a nonunifom density, this test provides a test that the full viscous stress (and velocity shear) tensors are calculated correctly from the conserved variables, and checks the correctness of the fluxes and source terms calculated therefrom. In Appendix A, we present a detailed exposition of the Navier Stokes equations, particularly their fluxes and source terms in a variety of common coordinate systems.
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