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Physics Astrophysics

astro-ph Watch Astrophysics

Tuesday 7 July

High Energy Astrophysical Phenomena

Probing magnetized accretion disk-jet systems: stellar mass to supermassive black holes

Mayank Pathak, Rohan Raha and Banibrata Mukhopadhyay

Ubiquitous nature of accretion disks and associated jets in modern astrophysics is extreme for black holes. The current state-of-the-art of black hole activities lies with modeling of underlying general relativistic magnetohydrodynamic (GRMHD) flows. These simulations have shown the importance of magnetic fields in the generation of outflows/jets and the overall dynamical evolution of the accretion flow. They also reveal critical insights into mechanisms that influence accretion dynamics, jet formation and stability. This further sheds light on the underlying magnetic field configurations based on magnetic field saturation leading to Standard and Normal Evolution: SANE, and Magnetically Arrested Disk: MAD. By employing SKA's high-resolution imaging and sensitivity, we can directly compare simulation outcomes with observational data, validating our models and enhancing our understanding of these phenomena. Key to this investigation is the examination of magnetic fields and their associated polarization signatures. Comparing the observational data from SKA with GRMHD simulations will facilitate a deeper analysis of the polarization properties, which can reveal the magnetic field geometry and dynamics in these extreme environments. The VLBI capabilities of SKA will prove instrumental in understanding jet morphologies and spectra of these systems due to its high spatial resolution. Collating these observations with GRMHD simulations will lead to a better understanding of the jet generation mechanisms and their interaction with ambient medium. By integrating advanced GRMHD simulations with SKA's capabilities, we aim to bridge theoretical predictions and observations, ultimately contributing to a more comprehensive understanding of the behavior of accreting black holes and their jets.
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High Energy Astrophysical Phenomena

Simulating the LOcal Web (SLOW): VII. Intergalactic magnetic field models for multi-messenger applications

Johannes Stoiber, Klaus Dolag, Francesca Capel et al. (+4 more)

Context. The propagation of ultra-high-energy cosmic rays (UHECRs) and ultra-high-energy gamma-rays remains an open question in astroparticle physics, with the intergalactic magnetic field (IGMF) playing a crucial role in deflecting charged particles and shaping electromagnetic cascade spectra. Characterizing the IGMF across cosmic large-scale structure is therefore essential for interpreting multi-messenger observations and constraining the magnetogenesis scenarios that seeded it. Aims. We aim to provide accurate IGMF models to the astroparticle physics community and test their properties and robustness. Methods. We analyze IGMF models derived from the constrained cosmological simulation SLOW alongside a set of rescaled magnetic field models. We further introduce a novel algorithm to determine an "ideal position" for galaxies lying below the constraining power of the initial conditions, enabling accurate line-of-sight magnetic field extraction toward relevant sources. Results. The models span a wide range of filling factors and sample distinct regions of the electron density-magnetic field strength phase space in filaments, while converging in the cores of galaxy clusters; the simulated field from SLOW best reproduces the IGMF derived from the electromagnetic gamma-ray cascade. Models extracted using the introduced "ideal position" yield improved accuracy and may benefit multi-messenger studies more broadly. The large-scale structure drift of simulated clusters exploited by the algorithm also offers a potential route to refining the simulation's constrained initial conditions.
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All authors Johannes Stoiber, Klaus Dolag, Francesca Capel, Benjamin Seidel, Michael Kachelrieß, Ludwig M. Böss, Jenny G. Sorce

High Energy Astrophysical Phenomena

Effects of Rotation on 3D Core-Collapse Supernova Models for Low-Mass Progenitors

Adam Burrows, Tianshu Wang and David Vartanyan

We explore the dependence upon rotation rate alone of various supernova observables simulated to their saturation for the explosion of a 9-$M_{\odot}$ progenitor. We find that the explosion energy is non-monotonic with, and weakly dependent upon, spin across a broad range of initial spins. The asymmetries of the blast depend weakly on spin, with faster spins leading to only slightly greater asymmetries. There is little significant pole-equator neutrino heating asymmetry during explosion, even for rapid rotation, and only for the fastest rotator does the neutrino heating rate diminish noticeably. Hence, the effects of rotation alone on all salient aspects of supernova dynamics are not large. We find that the recoil kick and spin are clearly aligned only for the most rapidly rotating model. Interestingly, for the fastest rotator, we witness a $T/|W|$ corotation instabilities near a value of 0.05 and spiral arm modes emerge. We find that the nucleosynthetic yields depend little upon the rotation rate and determine that the ratio of initial to final core spin period is near $\sim$4000, implying, given the modest inferred radio pulsar periods at birth, that the initial spin periods of most supernova cores are likely quite long. However, we focus on only one progenitor and do not include magnetic fields. Nevertheless, at least for low-mass progenitors which explode early, we find muted consequences of rotation in most major particulars across a wide range of initial spins.
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Astrophysics of Galaxies

J-PLUS: Spectral classification and photometric redshifts for 79 million sources in the fourth data release

A. Hernán-Caballero, H. Vázquez Ramió, C. López-Sanjuan et al. (+20 more)

We present spectral classifications and photometric redshifts for 79.2 million sources up to an r-band magnitude of 22 in Data Release 4 of the Javalambre Photometric Local Universe Survey (J-PLUS). Leveraging the 12-band J-PLUS filter system, we compare a template-fitting approach (LePhare) against LeMoNNADE, a morphology-blind machine learning pipeline that uses spectral mixing augmentation to overcome training set limitations. LeMoNNADE consistently outperforms template fitting in precision, robust scatter, and outlier rates. Including WISE infrared photometry breaks optical degeneracies between stars and quasars, reducing the catastrophic outlier rate for quasars from ~40% to ~23% and constraining systemic redshift bias to <1% up to z = 4. We find LeMoNNADE is also less susceptible to redshift aliasing, particularly when adopting the probability density function median. Because the spectroscopic training samples severely under-represent stars, we apply an Expectation-Maximization Bayesian calibration to recover unbiased class probabilities for the magnitude-limited sample. This reveals that extragalactic counts agree with the literature down to the r ~ 20.5 completeness limit. The inferred redshift distribution for r < 21 extragalactic sources peaks at z ~ 0.3, showing broad agreement with existing literature up to z ~ 0.6. The resulting catalogues represent a significant milestone for local Universe science, offering probabilistically calibrated classifications and distances while explicitly characterising faint-end limits and contamination.
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All authors A. Hernán-Caballero, H. Vázquez Ramió, C. López-Sanjuan, D. Muniesa, T. Civera, J. A. Fernández-Ontiveros, H. Domínguez-Sánchez, A. del Pino, J. A. L. Aguerri, S. Zarattini, V. Marra, A. J. Cenarro, D. Cristóbal-Hornillos, C. Hernández-Monteagudo, A. Marín-Franch, M. Moles, J. Varela, J. Alcaniz, R. A. Dupke, A. Ederoclite, L. Sodré Jr., R. E. Angulo, J. Zaragoza-Cardiel

Instrumentation and Methods for Astrophysics

A comparison of numerical schemes for driven subsonic MHD turbulence

Rüdiger Pakmor, Thomas Guillet, Rebekka Bieri et al. (+3 more)

Turbulence is ubiquitous in astrophysical systems, and since most cosmic gas is ionised, it supports magnetic fields. In turbulent environments, these fields are rapidly amplified through a small-scale dynamo. Multi-scale astrophysical simulations, however, rarely resolve this process adequately. Limited spatial dynamic range makes small-scale amplification sensitive to the numerical choices made in the hydrodynamics and magnetic field solvers. Here, we investigate idealised periodic boxes of driven subsonic turbulence with a weak seed magnetic field. These simulations with purely numerical dissipation provide a simple environment in which an efficient small-scale dynamo is expected. We aim to systematically compare the three widely used magnetohydrodynamics (MHD) codes Arepo, Athena, and Ramses across different divergence-control schemes: constrained transport, Powell cleaning, and Dedner cleaning. To minimise comparison bias, we adopt identical turbulent driving and analysis pipelines across all runs. At sufficient resolution, every code and scheme we test exhibits dynamo-like exponential amplification of the seed field until saturation. The structural properties of the magnetic field in both the kinematic and saturated regimes are consistent across schemes (with the exception of Arepo's constrained transport) and agree with theoretical expectations. Residual differences, particularly in kinematic amplification rates and saturation strengths at fixed resolution, appear attributable to varying levels of numerical diffusion. Notably, we find for this setup no systematic advantage of constrained transport over divergence-cleaning methods. We stress that this comparison, conducted in a highly idealised setting, represents a first step. Future extensions to more complex and physically realistic configurations remain essential.
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All authors Rüdiger Pakmor, Thomas Guillet, Rebekka Bieri, Christoph Pfrommer, Volker Springel, Romain Teyssier

Cosmology and Nongalactic Astrophysics

The Treble Clef radio phoenix and its old nonthermal filaments

A. Botteon, M. Brienza, K. Rajpurohit et al. (+15 more)

By inspecting data from the LOFAR Two-meter Sky Survey (LoTSS), we noticed a peculiar bright and filamentary radio source at low-galactic latitude ($b \approx 0.5 \deg$). This source, detected also in previous radio observations, was originally believed to be a pulsar, but was later suggested to be located in a heavily obscured galaxy cluster behind the Galactic plane. In this paper, we characterize for the first time the main properties of the host cluster (redshift, mass, temperature, X-ray luminosity, and dynamical status) by using X-ray observations performed with Chandra and SRG/eROSITA. In addition, by combining new uGMRT follow-up data with observations from the e LOFAR LBA Sky Survey (LoLSS), we perform a multifrequency, spatially resolved spectral analysis of the filamentary radio source (VLSS J0318.9+5755, nicknamed here the "Treble Clef" due to its morphology). We conclude that this source is a radio phoenix belonging to a massive, merging galaxy cluster in the Zone of Avoidance. We speculate that its complex morphology is shaped by gas motions generated in the intracluster medium during the ongoing merger, which are also likely responsible for the generation of the candidate radio halo tentatively observed in the cluster center. Owing to its highly filamentary morphology, brightness at $\lesssim$1 GHz, and extremely steep spectrum, reaching values of $\alpha > 4$ between 400 and 650 MHz, this source represents an ideal target for high-resolution, very-low-frequency follow-up observations with LOFAR2.0.
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All authors A. Botteon, M. Brienza, K. Rajpurohit, N. Lyskova, E. Churazov, I. Khabibullin, T. Pasini, E. O'Sullivan, G. Brunetti, F. De Gasperin, E. De Rubeis, F. Gastaldello, D. N. Hoang, R. Kraft, G. Schellenberger, R. Sunyaev, R. J. van Weeren, F. Vazza

Instrumentation and Methods for Astrophysics

HDRL Staff Strategy Meeting Report

Brian Thomas, Robert Candey, Jack Ireland et al. (+3 more)

HDRL held its first HDRL wide strategy meeting in January 2026, pulling in a majority of HDRL member staff and selected HDRL grantees. Just over 40 people attended with a few more online to listen to over 30 lightning talks presented by their colleagues and leaders, participate in several breakout and group discussions, and cast 324 votes on over 50 strategic topic ideas contributed by the attendees. The many ideas generated by attendees can be grouped into seven themes which describe the overall breadth of discussion at the meeting. These themes included: Metadata, Standards, and Semantics Discovery, Search, and Recommendation Modernizing HDRL User experience Modernizing HDRL Staff experience Modernized, Scalable, and Dependable Infrastructure for Compute and Storage Metrics and Impact Assessment Community Engagement and Sustainability Considering the gathered information and the interconnections between the prioritized ideas we concluded that several strategic areas for action exist. This document provides an overview of contributed materials and post meeting strategic analysis.
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All authors Brian Thomas, Robert Candey, Jack Ireland, Lan Jian, Rebecca Ringuette, Tressa Helvey-Kalsulke

Instrumentation and Methods for Astrophysics

Fast Graph-based Higher-Order Clustering Statistics on the GPU

Cristiano G. Sabiu

We present a significant update to GRAMSCI (GRAph Made Statistics for Cosmological Information; Sabiu et.al 2019), an algorithm for the fast computation of the general $N$-point spatial correlation function of any discrete point set embedded in $\mathbb{R}^n$. Utilizing the concepts of kd-trees and graph databases, we count all possible $N$-tuples in binned configurations within a given length scale. In this Version 2 update we describe several additions to the original code. We replace the binary-search inner loop, which cost $O(m\log m)$ per hub–spoke pair, where $m$ is the mean neighbor count, with a merge-walk algorithm that reduces the inner loop to $O(m)$. We implement a parity-decomposed 4pCF that separates the signal into even and odd channels, enabling direct tests of parity violation in the galaxy distribution. We estimate the disconnected 4pCF internally on the same graph to return the connected 4pCF. We provide a Python interface so the Fortran engine can be called directly from NumPy arrays. Finally, and principally, we present a GPU port of the full query engine (OpenACC): the 3pCF, 4pCF, and parity-decomposed 4pCF kernels run on a single consumer GPU with measured speedups of $2.6\times$ (3pCF) to $9\times$ (4pCF) over a 64-thread CPU node, and an out-of-core tiling scheme allows graphs far exceeding device memory. We measure a $9\times10^9$-edge BAO-scale 3pCF on a 24\,GB card with ${\sim}20\%$ overhead. We validate the code against its CPU reference, against analytic injection tests, and demonstrate BAO-scale applications on the DESI DR1 LRG sample compared against the EZmock ensemble.
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Cosmology and Nongalactic Astrophysics

Skipping the rungs! Calibrating distance indicators through their clustering with galaxies

Madeline L. Cross-Parkin, Leonardo Giani, Cullan Howlett et al. (+1 more)

We show that angular cross-correlations between distance indicators and galaxy redshift catalogues, when interpreted within an assumed cosmological model, can constrain potential biases in distance measurements induced by calibration systematics. As a test case, we consider a simple scenario in which a constant calibration offset $\Delta M$ shifts all observed distances by a multiplicative factor, and we produce Fisher forecasts for the constraining power on $\Delta M$ and $H_0$ from existing and upcoming surveys. In our most optimistic scenario, based on the expected number of SN Ia observed by LSST and the DESI final data release, we find $\sigma_{\Delta M} \approx 0.05$ and $\sigma_{H_0} \approx 1.81~\mathrm{km~s^{-1}~Mpc^{-1}}$. This has important implications for the Hubble tension, since explaining the discrepancy purely as a calibration systematic in low-$z$ measurements would require $\Delta M \approx 0.13$.
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All authors Madeline L. Cross-Parkin, Leonardo Giani, Cullan Howlett, Tamara M. Davis

High Energy Astrophysical Phenomena

Minimum Energies and Magnetic Field Strengths of Edge-brightened Compact Symmetric Objects

Tirth D. Surti, Martijn S. S. L. Oei, Anthony C. S. Readhead et al. (+1 more)

Compact symmetric objects (CSOs) are subkiloparsec radio sources with two-sided emission about a core resulting from jets that are not relativistically beamed towards the observer. This relative simplicity makes them attractive targets to study the launching and evolution of relativistic jets. We use radio surveys and spatially resolved VLBA observations to estimate the minimum energies and magnetic field strengths of a subset of edge-brightened CSOs (CSO-2s). These are necessary to test models of CSO-2 formation via stellar capture and evolution via synchrotron cooling. By treating the observed X-ray emission of CSO-2s as inverse Compton emission from synchrotron and external photon fields, we estimate a mean departure from the minimum energy magnetic field strengths of ${\sim}2\times$, suggesting that CSO-2 lobes are close to minimum energy. Typical lobal minimum energy magnetic field strengths of $20$ mG suggest that once the jets shut off, luminous CSO-2s should fade at GHz frequencies within ${\sim}10^{3}$ years. We find that CSO-2 minimum energies are systematically larger than previously estimated. If luminous CSO-2s result from tidal disruption events, a majority would require the capture of massive stars $>1 \ M_{\odot}$ assuming jet launching efficiencies less than $100\%$.
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All authors Tirth D. Surti, Martijn S. S. L. Oei, Anthony C. S. Readhead, Andrew G. Sullivan

Instrumentation and Methods for Astrophysics

LUnar-based Survey for Time-domain Exploration and Research network (LUSTER-net)

T. S. Boyajian, R. A. Street, B. Fleming et al. (+7 more)

LUSTER-net is a lunar-surface UVOIR observatory network mission concept for time-domain astrophysics. The concept envisions a scalable array of approximately 6-12 commonly designed telescope nodes, with apertures in the $\sim0.5-1$ m class, distributed across the lunar surface to provide long-duration monitoring, rapid follow-up, and coordinated imaging and spectroscopy of transient and variable sources. By combining continuous observing windows from the lunar surface with adaptive network scheduling, LUSTER-net would provide persistent UVOIR characterization of discoveries from facilities such as Rubin, Roman, ULTRASAT, UVEX, and multi-messenger observatories. The science enabled includes exoplanet atmosphere studies, microlensing parallax, Solar System object characterization, fast transients, electromagnetic counterparts to multi-messenger events, and broader UVOIR variability studies. This white paper outlines the science motivation, notional architecture, implementation trades, and role of LUSTER-net as a step toward future lunar astrophysics facilities.
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All authors T. S. Boyajian, R. A. Street, B. Fleming, F. Marchis, J. Morse, P. Gandhi, J. Turner, G. Rau, A. Tanner, A. Sohani

Astrophysics of Galaxies

High $^{12}$C/$^{13}$C isotopic ratios toward G+0.693-0.027: evidence for gas inflow to the Central Molecular Zone

L. Colzi, O. Sipilä, I. Jiménez-Serra et al. (+4 more)

Isotopic ratios are key tracers of Galactic chemical evolution because different isotopes are synthesized through distinct stellar nucleosynthesis processes. While the $^{12}$C/$^{13}$C ratio increases with galactocentric distance across the Galactic disc, measurements in the Central Molecular Zone (CMZ) have historically yielded low values ($\sim$3-30), often affected by high optical depths. We aim to determine the initial $^{12}$C/$^{13}$C ratio of the parent material of the CMZ molecular cloud G+0.693$-$0.027 using optically thin molecular tracers and correcting for isotopic fractionation. We analyzed an ultra-high-sensitivity spectral survey obtained with the IRAM 30m and Yebes 40m telescopes, detecting single and double $^{13}$C isotopologues of HC$_3$N and HC$_5$N. Column densities and isotopic ratios were derived and compared with astrochemical models including $^{13}$C- and $^{15}$N-isotopologues to quantify isotopic fractionation. We derive $^{12}$C/$^{13}$C ratios of $36.7\pm1.0$ for HC$_3$N (using double $^{13}$C isotopologues) and $38.8\pm1.5$ for HC$_5$N, significantly higher than previous CMZ estimates based on simpler molecules. The models indicate low to intermediate isotopic fractionation at early times ($<3\times10^4$ yr), implying an initial $^{12}$C/$^{13}$C ratio of $\sim$48 for the gas from which present-day CMZ molecular clouds formed. The inferred range (37-48) is consistent with values observed at Galactocentric distances of 3-5 kpc, supporting a scenario in which the CMZ is replenished by gas inflows from the Galactic disc driven by the Galactic bar, with a possible contribution from less chemically processed material accreted from external systems such as dwarf galaxies.
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All authors L. Colzi, O. Sipilä, I. Jiménez-Serra, V. M. Rivilla, M. Sanz-Novo, S. Martín, S. Zeng

Cosmology and Nongalactic Astrophysics

One with HI: Modelling HI Intensity Mapping one-point statistics including systematics

Bernhard Vos-Gines and Cora Uhlemann

Neutral hydrogen (HI) traces the dark matter distribution of the Universe. Upcoming surveys such as the Square Kilometre Array Observatory (SKAO) will trace neutral hydrogen up to z < 6 using several detection techniques including Intensity Mapping, which offers a unique window to explore the post-reionization Universe. Beyond two-point statistics promise to extract additional non-Gaussian information but require an accurate modelling of observational systematics such as foregrounds and the telescope beam. This work develops a theoretical model for the HI one-point probability density function (PDF) in spherical cells based on large-deviation statistics and spherical collapse for dark matter along with a nonlinear tracer bias and stochasticity parameterisation. It incorporates foreground removal and telescope beam effects that are validated against high-resolution simulations. We show that, despite these observational systematics, the HI PDF is able to capture additional non-Gaussian information from HI intensity maps compared to the power spectrum and can thus tighten constraints on cosmological parameters, breaking the degeneracy between the linear bias and the clustering amplitude.
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Earth and Planetary Astrophysics

A parameterised approach to disequilibrium retrievals in the JWST era: Application to NIRCam observations of HD 189733b

Jake Taylor, Shang-Min Tsai, Vivien Parmentier et al. (+2 more)

Atmospheric retrievals are a widely used technique for inferring the physical and chemical properties of exoplanetary atmospheres from observed spectra. A common simplifying assumption in such analyses is that the atmosphere is in thermochemical equilibrium, which allows the use of precomputed chemical abundance grids as a function of pressure, temperature, metallicity ([M/H]), and carbon-to-oxygen ratio (C/O). However, exoplanet atmospheres often deviate from equilibrium, particularly at lower temperatures or in the presence of strong vertical mixing. In this work, we investigate the impact of disequilibrium chemistry on retrieval outcomes by generating synthetic James Webb Space Telescope (JWST) observations of HD\,189733\,b with varying strengths of vertical mixing. We demonstrate that assuming thermochemical equilibrium can lead to significant biases in the retrieved atmospheric parameters, including incorrect estimates of C/O and [M/H]. To address this, we incorporate transport-induced quenching of carbon and nitrogen-bearing species into the retrieval framework by allowing the quench pressures to be free parameters. We show that this approach recovers the correct bulk atmospheric properties in most cases. Finally, we apply our disequilibrium retrieval model to published JWST/NIRCam transmission observations of HD\,189733\,b and find tentative evidence for quenching. We also find tentative evidence for the photochemically active region of the atmosphere via a newly developed H$_2$S parameterisation, this is the first time this has been constrained in a hot Jupiter atmosphere.
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All authors Jake Taylor, Shang-Min Tsai, Vivien Parmentier, Chloe Fisher, Michael Line

High Energy Astrophysical Phenomena · Cross-listed from physics.plasm-ph

Exact 1D Nonlinear Solutions for Proton-Driven Plasma Wakefields

D. Tsiklauri

We extend the classical 1D nonlinear relativistic plasma wakefield paradigm to evaluate the pristine fluid profiles driven by intense relativistic proton trains under the comoving coordinate approximation. Using an intense two-bunch scheme, our adaptive integration model is validated down to machine precision against exact closed-form cold-fluid invariants, confirming that interface boundary corners represent physical step discontinuities in the second potential derivative. Scaling to an $N=100$ micro-bunch train, we resolve macroscopic phase-accumulation and subsequent nonlinear detuning by deriving a closed-form, parameter-free piecewise analytical envelope expression. This solution successfully maps the initial unattenuated quadratic coherent growth alongside the flat asymptotic horizontal saturation horizon governed by nonlinear energy conservation. Furthermore, the framework analytically evaluates the transient envelope overshoot, tracking its decay onto the saturation boundary via an exact phase-slip integration length scale. Providing immediate, ready macro-envelope bounds, this computationally inexpensive tool eliminates empirical adjustments and yields a robust mathematical baseline designed to guide and accelerate complex, multi-dimensional particle-in-cell (PIC) simulations through rapid parameter space exploration before deploying heavy computational assets. It establishes an efficient foundation to optimize asymmetric, custom-shaped driver profiles required to break the fundamental symmetric transformer ratio limit of 2 to make current particle accelerators more efficient.
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Earth and Planetary Astrophysics

Size, shape, density, and atmospheric limit of (50000) Quaoar revealed from 14 years of stellar occultation

Giuliano Margoti, Felipe Braga-Ribas, José Luis Ortiz et al. (+173 more)

We present results from 28 stellar occultations by the large Trans-Neptunian Object (50000) Quaoar registered between 2018 and 2025. By performing a joint analysis of this occultation data-set, along with other 9 published events, we were able to fit an oblate ellipsoid shape, with equatorial semi-axes, a and b of 566.1+2.5-2.2 km, and a polar semi-axis, c, of 511.2+3.6-3.7 km. It provides an equivalent volumetric diameter of 1094.4 +/- 4.6 km and polar oblateness of 0.097 +/- 0.011. Considering an absolute magnitude of H = 2.79 +/- 0.35, we derive a geometric albedo of pV = 0.125 +/- 0.038. We have derived new upper limits to the surface pressure of a CH4 atmosphere of 0.15 nbar (1-sigma) and 0.65 nbar (3-sigma). We also provide a table with the 36 new astrometric positions for Quaoar. Using the new system mass derived from Weywot's orbit around Quaoar, we calculated a density of 1.760 +/- 0.109 g/cm3. Moreover, from the derived size and rotation period (8.8394 +/- 0.0002 hours (Ortiz et al. 2003)), we calculate that, if Quaoar is in Maclaurin hydrostatic equilibrium state, it would have a density of 1.859 +/- 0.200 g/cm3. This result, within the error bars, is compatible with the value we found. Therefore, this work shows that Quaoar can be a Maclaurin object, being eligible as a dwarf planet.
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All authors Giuliano Margoti, Felipe Braga-Ribas, José Luis Ortiz, Bruno Sicardy, Josselin Desmars, B. E. Morgado, Eros de Oliveira Gradovski, Chrystian Luciano Pereira, Pablo Santos-Sanz, Altair Ramos Gomes-Júnior, Julio Ignacio Bueno de Camargo, Marcelo Assafin, Vieira-Martins Roberto, Yucel Kilic, Damya Souami, René Duffard, Gustavo Benedetti-Rossi, Tiago Pinheiro, Maísa Poiani, Eduardo Rondón, Marcelo Emilio, Dave Herald, Rafael Sfair, Nicolas Morales, Francois Colas, Frédéric Vachier, Mónica Vara Lubiano, Rodrigo Boufleur, Mert Acar, Francisco J. Aceituno, Miguel R. Alarcon, Sinan Alis, Sergio Alonso, Javier Alonso-Santiago, Flavia Amadio, Laerte Andrade, Pascal André, Jonatã Arcas-Silva, Alper K. Ateş, David Lafuente Aznar, Michael Backes, Mehmed Naim Bagiran, Nelson Balcar, M. A. Barry, Khalid Barkaoui, Wolfgang Beisker, Kirk Bender, Zouhair Benkhaldoun, Svetlana Boeva, Eberhard H. R. Bredner, Richard Busuttil, A.~Y.~Burdanov, Oscar Canales, Javier Zaragoza-Cardiel, V. Casanova, Matheus Leal Castanheira, Peter Ceravolo, Steven J. Conard, Luciano Negrello Correa, Daniel V. Cotton, V. S. Dhillon, Serena Diamond, Vlad Dumitrescu, Joan Dunham, David W. Dunham, Christopher L. Duston, Eslam Elhosseiny, Orhan Erece, Sila Eryilmaz, Emilio J. Fernandez-García, Suleyman Fisek, R. Scott Fisher, Clyde Foster, Eric Frappa, Antonio Frasca, Jonah Frey, José María Gómez-Limón Gallard, Jose Luis Maestre Garcia, Dave Gault, Kosmas Gazeas, Kai Getrost, Michael Gillon, Alan Gilmore, Robert Glassey, K. D. Green, William Hanna, Nicholas J. Haigh, Dean Hooper, Kamil Hornoch, Dragana Ilic, Cristóvão Jacques, Felix~Jankowsky, Emmanuel Jehin, Selami Kalkan, Roxanne Kamin, Monika K. Kamińska, Shai Kaspi, J. J. Kavelaars, Stephen Kerr, Ulrich Kolb, Richard Komvzik, Dogan T. Koseoglu, Mike Kretlow, Sangeeta Kuchibhotla, Jean Lecacheux, Arnaud Leroy, Alexios Liakos, Luana Liberato, Peter Lindner, S. P. Littlefair, Jose M. Madiedo, Natalio Maícas, Marcio Malacarne, Paul Maley, Jan Mánek, Anna Marciniak, Patrick Martinez, Ramón Iglesias-Marzoa, Graeme McKay, Steve Messner, Zdeněk Moravec, Eduardo Fonseca Morato, Messias Fidêncio Neto, John Newman, Vadim Nikitin, Richard Nolthenius, Peter Nosworthy, Mohammad Odeh, W. Ogloza, Sibel Otken, Sacit Özdemir, Andras Pal, Ashley Pennell, Amauri Pereira, Carles Perello, Jean Perkins, Konstantin von Poschinger, Thiago do Prado, Theodor Pribulla, Sohrab Rahvar, Giovana Ramon, Seth Redfield, Claudine Rinner, Jean-Pierre Rivet, Johannes Antunes Nascimento Ro, rigues Antonio Román-Reche, Flavia Luane Rommel, T. de Santana, T. Santana-Ros, Antoni Selva, Christoph M. Schaefer, Andrew Scheck, Carles Schnabel, Olivier Schreurs, Andreas Schweizer, M. Serra-Ricart, Ned Smith, Colin Snodgrass, Eda Sonbas, A. Sota, Rafael Ribeiro de Sousa, Fabio Augusto Spina, Theodore Swift, Robert Szakats, Ali Takey, Mohammad F. Talafha, Ramachrisna Teixeira, Zahide Terzioğlu, Qiushi Chris Tian, Vagelis Tsamis, Eyüp Kaan Ülgen, Oliver Vince, Marcos Rincon Voelzke, Christian Weber, Julien de Wit, Michal Zejmo

High Energy Astrophysical Phenomena

Finite-Field QED Corrections to Vacuum Birefringence and Magnetar Polarization Transport

S. Abbassi, F. A. Chishtie and S. R. Valluri

We study low-energy photon propagation in a constant magnetic field within the finite-field one-loop Heisenberg–Euler framework and apply the resulting mode-dependent refractive indices to magnetar polarization transport. In a centered-dipole model, the polarization-limiting radius is unchanged to better than $10^{-12}$ because mode decoupling occurs at $\sim10^2R_{\rm NS}$, where $B\ll B_{\rm cr}$. Near the surface, however, the weak-field Cotton–Mouton expression overestimates the accumulated birefringent phase by up to a factor $2.9$ at $10^{15}$~G. At the plasma–vacuum resonance, finite-field corrections reduce the resonance density by $32\%$ and raise the adiabatic conversion energy by $14\%$ for 1E~1547.0$-$5408; the corresponding changes are factors $2.6$ and $1.37$ for 1RXS~J1708$-$4009, and factors $9.7$ and $2.13$ for SGR~1806$-$20, the latter controlled by the strong-field asymptote. The parallel-mode magnetic response remains positive and exhibits a broad maximum near $17B_{\rm cr}$. Its strict $\mathcal O(\alpha)$ expansion is monotonic, indicating that the detailed position and profile of the maximum are not controlled beyond the present approximation and require higher-loop assessment. These results identify vacuum-resonance observables as the most sensitive channel for testing finite-field QED in magnetars.
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Instrumentation and Methods for Astrophysics

slicersim: A python package to simulate image slicer spectroscopic observations – application to the Lazuli Spectrograph

M. Rigault, Y. Copin, G. Aldering et al. (+8 more)

Integral Field Spectroscopy (IFS) is a key technique to study galaxies, stellar and planetary systems, and transients, by spatially splitting the scene and dispersing this light onto the detector. This technique is now central for many modern telescopes, including the Lazuli Space Observatory which will host a low spectral-resolution image slicer spectrograph. To prepare for future IFS-equipped instruments and to better understand the systematics of current ones, realistic simulations are needed. We present slicersim, a Python package designed to simulate IFS observations. slicersim is a modular and flexible tool that allows the user to build a scene, define a telescope, a spectrograph, and a detector, and to simulate the resulting observation, including various sources of noise and instrumental effects. The package is designed to be easily extensible to any IFS, with a current focus on that from the Lazuli Space Observatory. In this paper, we present the structure and logic of the package, detailing its main components, and providing an example of its usage. Using slicersim we demonstrate the feasibility of a large cosmology campaign on Lazuli – a sample of 8000 Type~Ia Supernovae uniformly distributed between $z=0$ and $z=1.5$, observed within the first few years of its operations for a typical average signal-to-noise of 25 per resolution element rest-frame optical wavelengths.
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All authors M. Rigault, Y. Copin, G. Aldering, J. Edelstein, G. Furesz, J. Lasker, T. Miller, S. Perlmutter, A. Roy, E. Schlawin, G. Stefansson

Earth and Planetary Astrophysics

A generalised microbial cell model for methane biosignature predictions

Arwen E. Nicholson and Nathan J. Mayne

The majority of potentially habitable planets detected to date are likely quite different to Earth, for example, being larger in radius and mass, differing rotation rates and with host star spectra unlike the Sun. Therefore the first alien life detected will potentially be living in conditions not found on our planet. This necessitates a generalised approach to modelling biology that can be applied to numerous planetary scenarios, built on fundamental knowledge of life on Earth, but not limited by it. Here, we explore a generalised model of a microbial cell, whose metabolic rate is governed by thermodynamics and substrate diffusion across its cell wall. We model a single-species biosphere consisting of methane producing microbes and determine how changing the cell size, cell death rate and biomass synthesis cost influence the biosignature on the planet - in this case methane. We discuss approaches to predicting upper estimates for the biosignature gas abundance and the applicability of the model to other metabolisms. This tool adds to the body of work attempting to grapple with the complexity of potential alien biospheres.
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High Energy Astrophysical Phenomena

The link between extreme particle acceleration and X-ray binary jets

Laura Olivera-Nieto, Fraser J. Cowie, Sera Markoff et al. (+2 more)

The detection of multi-TeV radiation from a handful of black-hole X-ray binaries (BHXRBs) has positioned the source class as promising candidate to explain the cosmic-ray flux in the PeV energy range. To determine what distinguishes the systems detected in the gamma-ray range from the rest of the population, we build on existing catalogues of BHXRBs by including information on the radio and gamma-ray emission from these systems. We then compare the $>100$ TeV gamma-ray luminosity to different properties of the systems and evaluate the strength of the (rank) correlation between them. Additionally, we compare the distribution of BHXRBs with the positions of unassociated gamma-ray sources in the 1LHAASO and 1HGPS catalogues. We find no correlation with the mass of the compact object, the companion mass or the inclination angle. Instead, we find evidence for a strong correlation between the gamma-ray luminosity and the radio and hard-state X-ray luminosities in our sample. The limited number of gamma-ray detections means that this correlation cannot yet be claimed as statistically significant. We find indications that a high (>20%) duty cycle (defined as fraction of time spent in outburst) might be a requirement for $>100$ TeV gamma-ray loudness. We find significant evidence ($>3\sigma$) that BHXRBs are located near unassociated gamma-ray sources in the region of the sky not covered by LHAASO. This evidence is only significant when comparing to BHXRBs with a reported detection in the radio band. We conclude that radio-bright BHXRBs with a high duty cycle are more likely to be detected as gamma-ray sources than sources which are not detected in the radio band or those with low duty cycles. This result suggests that the particles responsible for the gamma-ray emission are associated with the jets, either accelerated within them or via their interaction with their surroundings.
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All authors Laura Olivera-Nieto, Fraser J. Cowie, Sera Markoff, Rob Fender, Justine Crook-Mansour

Solar and Stellar Astrophysics

White dwarfs within 13 pc: insights from ultraviolet spectroscopy

Mairi W. O'Brien, Pier-Emmanuel Tremblay, Boris T. Gänsicke et al. (+10 more)

We present a comprehensive multi-wavelength spectroscopic and photometric analysis of the 44 confirmed white dwarfs within 13 pc of the Sun. Combining flux-calibrated ultraviolet spectroscopy from the Hubble Space Telescope (STIS and COS) with ground-based optical spectroscopy, as well as photometry from Gaia, 2MASS, and WISE, we employ a combined fitting method to calculate atmospheric parameters. Each white dwarf is fitted with a bespoke model depending on its detailed atmospheric composition. Two strongly magnetic stars could not be fitted due to the complex splitting of their spectral lines. We find a systematic discrepancy in hydrogen-atmosphere white dwarfs with effective temperatures below 10,000K, where fits incorporating ultraviolet spectra result in effective temperatures that are 1 - 5 per cent higher than those derived from optical and infrared photometry alone. We re-classify three helium-atmosphere white dwarfs as metal enriched following a magnesium detection in their near-ultraviolet spectra: WD 0435-088, WD 1132-325 and WD 1917+386. In total, we identify five stars in the sample for which metals are only detected in the ultraviolet. Overall, we find that 30 per cent of the 13 pc white dwarfs show spectroscopic evidence of evolved planetary systems. Our analysis reveals no measurable difference between the hydrogen content of DQ and DC white dwarfs, although the upper limits of carbon in DCs are significantly below that of the DQ population. We find a multiplicity fraction of 33 per cent for the 13 pc white dwarfs.
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All authors Mairi W. O'Brien, Pier-Emmanuel Tremblay, Boris T. Gänsicke, Mark A. Hollands, Detlev Koester, Snehalata Sahu, Antoine Bédard, Andrew M. Buchan, Tim Cunningham, John H. Debes, Jay Farihi, J. J. Hermes, Piotr M. Kowalski

High Energy Astrophysical Phenomena

Unravelling Turbulence and Magnetic Fields in Galaxy Clusters with SKA and XRISM

Kohei Kurahara, Takuya Akahori, Amit Seta et al. (+5 more)

This chapter proposes a research framework to quantitatively investigate non-thermal components in the Intracluster Medium (ICM) of galaxy clusters, which are critical ingredients for governing energy transport, structure formation, and particle acceleration. Turbulence, primarily driven by cluster mergers, is the leading mechanism for re-accelerating cosmic ray electrons (forming radio halos) and amplifying magnetic fields (via the turbulent dynamo). Observational understanding of both the turbulence and magnetic fields is rapidly evolving: the high-resolution X-ray spectrometer XRISM is directly measuring the velocity properties of the thermal ICM, providing insights into the kinetic energy of turbulence. Concurrently, high-sensitivity low-frequency radio observations, including SKA pathfinders, are mapping non-thermal components and magnetic structures through diffuse synchrotron emission and high-density Faraday Rotation Measure (RM) grids. The synergy between XRISM and SKA offers a decisive paradigm shift. XRISM's velocity maps, with its high energy resolution (<7 eV FWHM), combined with SKA-Mid's capability to deliver high-resolution RM grids ($\sim 100$–$200~\rm deg^{-2}$) and high-dynamic-range imaging, will allow for the first direct, multi-wavelength comparison of the turbulent energy properties (from X-ray) and the magnetic field properties (from radio). This joint analysis will validate Magnetohydrodynamic (MHD) simulation predictions, clarify the process of turbulent energy cascade and decay, and ultimately lead to a comprehensive understanding of the co-evolution of turbulence, magnetic fields, and cosmic rays in the largest laboratories of the Universe.
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All authors Kohei Kurahara, Takuya Akahori, Amit Seta, Kosuke Nishiwaki, Kazuhiro Nakazawa, Yuki Omiya, Daisuke Ito, Kosei Sakai

Solar and Stellar Astrophysics

Spectral Ratio Analysis: probing of a new suite of stellar activity indicators as a tool for astrophysical noise mitigation

Jean C. Costes, Christopher A. Watson, Ernst de Mooij et al. (+6 more)

Stellar activity is the main barrier to detecting and/or confirming low-mass/long-period (and Earth-analogue) planets using radial-velocity (RV) measurements. Searching for reliable indicators that better trace magnetic activity may be key for both distinguishing more clearly between stellar and planetary signals, and for probing the underlying physics occurring on the stellar surface. In this work we have compared observations taken for magnetically active and inactive stellar phases over multiple time scales to study the spectral imprint due to varying stellar activity. This serves as a proof-of-concept demonstration of a technique (named Spectral Ratio Analysis, SRA) that can be used to isolate activity-driven changes directly in the stellar photospheric absorption lines where RVs are measured. Using 14 relatively quiet and well sampled G- and K-type stars that show stellar activity cycles, we identified hundreds of activity-sensitive spectral features. Reducing this variability information into two global metrics – amplitude and velocity shift – uncovers potential evidence of a decoupling of the photospheric and chromospheric responses to stellar activity in earlier-type stars. Additionally, potential signatures of the variations in the magnitude of the suppression of the convective blueshift throughout the activity cycle were observed via SRA. Finally, we show that these SRA indicators better capture RV variability than classical activity proxies, such as the chromospheric logR'HK index and other cross-correlation function-based parameters such as BIS and FWHM, by up to a factor of two. The direct link between photospheric line behaviour and stellar-induced RV variability offers a promising path for improving astrophysical noise mitigation.
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All authors Jean C. Costes, Christopher A. Watson, Ernst de Mooij, Katlyn L. Hobbs, Dana Clarice S. Yaptangco, Yvonne C. Unruh, Megan Bedell, Nadège Meunier, Thomas D. Mitchell

High Energy Astrophysical Phenomena

SN 2022erq: A Superluminous Thermonuclear Supernova with Escalating Preexplosion Mass Loss

Qian Zhai, Jujia Zhang, Xiaofeng Wang et al. (+51 more)

We present a photometric and spectroscopic study of the superluminous Type Ia supernova SN 2022erq. Its early spectra, dominated by iron-group elements with weak intermediate-mass features, might indicate highly efficient nuclear burning, broadly similar to that inferred for some overluminous SNe Ia. The rapid emergence and persistence of narrow Balmer emission lines superposed on this iron-rich spectrum provide clear evidence of long-lived interaction with a hydrogen-rich circumstellar medium (CSM), establishing SN 2022erq as a member of the rare Ia-CSM class. SN 2022erq reached a peak bolometric luminosity of about 8 x 10^43 erg/s and exhibited an exceptionally slow post-peak decline, indicating that its light curve is dominated by long-duration ejecta-CSM interaction. By combining H-alpha diagnostics with bolometric light-curve modeling, we reconstruct the pre-explosion mass-loss history of the progenitor. The mass-loss rate escalated by one order of magnitude over the final decades, rising from about 0.04 to about 0.6 solar masses per year. This surge produced a massive, extended CSM shell of about 3 solar masses out to about 3.5 x 10^16 cm. The young stellar environment (about 100 Myr) together with this substantial, extensive CSM points to a progenitor system consisting of a white dwarf and an intermediate-mass companion that underwent increasing mass loss prior to explosion.
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All authors Qian Zhai, Jujia Zhang, Xiaofeng Wang, A. Pastorello, Alexei V. Filippenko, József Vinkó, Thomas G. Brink, Yunkun Han, G. Valerin, N. Elias Rosa, Yongzhi Cai, Weili Lin, Yi Yang, WeiKang Zheng, Xiangcun Meng, Chengyuan Wu, Liping Li, Zeyi Zhao, J. Craig Wheeler, Jose L. Prieto, Jialian Liu, Gaici Li, Shengyu Yan, Fangzhou Guo, C. P. Gutiérrez, E. Kankare, Peter Lundqvist, S. Moran, A. Reguitti, I. Salmaso, M. D. Stritzinger, S. Williams, J.-W. Zhao, D.-D Shi, Jianrong Shi, Z.-H. Peng, Tengfei Song, Yongyuan Xiang, Attila Bódi, Borbála Cseh, Ágoston Horti-Dávid, Csilla Kalup, Levente Kriskovics, Réka Könyves-Tóth, András Pál, Bálint Seli, Ádám Sódor, Róbert Szakáts, P. A. Mazzali, T. Kravtsov, K. Matilainen, T. M. Reynolds, L. Galbany, Bo Wang

Solar and Stellar Astrophysics

The Best Guess: Testing new and old formalisms for the common envelope against observations

Riley Thai, Amanda Karakas, Zara Osborn et al. (+4 more)

We present a systematic test of formalisms for common envelope evolution by forward-modelling observable post-common envelope binaries. We compare predictions from the $\alpha$-formalism, and the Two-stage and SCATTER formalisms against observed post-common envelope binaries, including wide binaries with ultra-massive white dwarfs and central binaries of planetary nebulae. The angular momentum-based SCATTER formalism does not predict populations which match the complete observed population, even with adjustments to its parameters. We take this as indicative of fundamental challenges with using the orbital angular momentum balance to predict common envelope outcomes. The energy-based $\alpha $ and hybrid Two-stage formalisms both well-replicate the observed population. $\alpha_{\rm CE} \sim 0.2\text{--}0.3$ can match current observations, in agreement with previous works. Recombination energy is necessary, but only a fraction of it ($\sim\! 10\text{--}40\%$) can contribute in order to predict IK Peg-like binaries with ultra-massive white dwarfs at the correct orbital periods. Our work suggests energy-based formalisms remain the most accurate for predicting common envelope outcomes, but more observations can constrain the recombination contribution and how these outcomes systematically vary with the donor mass.
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All authors Riley Thai, Amanda Karakas, Zara Osborn, Robert Izzard, Ryosuke Hirai, Alex Kemp, Simon Campbell

Instrumentation and Methods for Astrophysics

Long-term performance of SiPMs in space environment measured by GRBAlpha, GRBBeta, and VZLUSAT-2 CubeSats

Jakub Ripa, Filip Munz, Marianna Dafcikova et al. (+46 more)

In this work, we report the successful application of silicon photomultipliers (SiPMs) in gamma-ray burst (GRB) detectors used in CubeSats operating in the low Earth orbit (LEO) radiation environment. It is known that SiPMs are susceptible to radiation damage, leading to an increase in the dark count rate. This results in an increase in the low-energy threshold in detectors combining SiPMs and scintillators. Despite this drawback, they became popular in gamma-ray detectors on CubeSats due to their low operating voltage, small size and fast response. Therefore, it is important to characterise their long-term performance in the space environment. Here, we describe the changes in the dark count rate and low-energy threshold of S13360-3050PE multi-pixel photon counters (MPPCs) by Hamamatsu Photonics K.K., using measurements from the GRBAlpha, GRBBeta, and VZLUSAT-2 CubeSats. In the case of GRBAlpha, the measurement of SiPM performance in space lasted over 4 years. GRBAlpha was a 1U CubeSat launched on 2021/03/22 to a 550 km altitude polar orbit carrying a CsI(Tl) scintillator GRB detector employing eight MPPCs and sensitive in the range of ~30-900 keV. GRBAlpha de-orbited on 2025/06/09. VZLUSAT-2 was a 3U CubeSat launched on 2022/01/13 to a 535 km altitude polar orbit and de-orbited on 2025/11/30. GRBBeta was launched on 2024/07/09 to a 580 km altitude, 62{\deg} inclination orbit. Both VZLUSAT-2 and GRBBeta carry detectors similar to the one on GRBAlpha. We have flight-proven the Hamamatsu MPPCs S13360-3050 PE and demonstrated that SiPMs, shielded by 2.5 mm of PbSb alloy, can be used in a LEO environment on a scientific mission lasting beyond 4 years. This shows the potential for SiPMs to be employed in future satellites.
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All authors Jakub Ripa, Filip Munz, Marianna Dafcikova, Andras Pal, Norbert Werner, Masanori Ohno, Laszlo Meszaros, Balazs Csak, Pavel Kosik, Michaela Duriskova, Lea Szakszonova, Martin Kolar, Tomas Vitek, Nikola Husarikova, Filip Hroch, Michal Pazderka, Yasushi Fukazawa, Hiromitsu Takahashi, Tsunefumi Mizuno, Jean-Paul Breuer, Masato Yokota, Kazuhiro Nakazawa, Hirokazu Odaka, Yuto Ichinohe, Tomas Urbanec, Ales Povalac, Miroslav Kasal, Miroslav Smelko, Peter Hanak, Gabor Galgoczi, Martin Topinka, Hsiang-Kuang Chang, Tsung-Che Liu, Chih-Hsun Lin, Chin-Ping Hu, Che-Chih Tsao, Kaustubha Sen, Chih-En Wu, Jakub Kapus, Jan Hudec, Marcel Frajt, Maksim Rezenov, Vladimir Daniel, Petr Svoboda, Juraj Dudas, Martin Sabol, Ivo Vertat, Robert Laszlo, Martin Koleda

Astrophysics of Galaxies

Low-Frequency Recombination Lines from Galaxies and AGN over Cosmic Time

Kimberly L. Emig, Sergei Balashev, Francoise Combes et al. (+10 more)

Radio recombination lines (RRLs) at low frequencies (<10 GHz) can provide a multi-phase view of interstellar gas in nearby galaxies, absorption-line-systems, and AGN. Hydrogen RRLs arise in fully ionized gas and carbon RRLs trace elusive cold-HI and CO-dark molecular gas. Low frequency RRLs are typically stimulated by the radio continuum and thus may be observable within or against radio bright sources out to cosmological distances (z ~ 6). Although long sought after, RRLs were only recently detected outside of the local universe (z ~ 1; Emig et al., 2020, 2023). Such detections have been made possible by the advancement of wide-bandwidth spectral-line surveys on next-generation low-frequency telescopes. Precursors and pathfinders to the SKA have opened up this field of research and will make significant advancements over the next years by enabling surveys over large source samples. The SKA will provide access to the crucial frequency ranges where RRL line intensity is brightest. Furthermore, multi-band SKA measurements will fully characterize gas physical conditions. Key extragalactic science of low frequency RRLs will focus on (i) the conversion of baryonic material into stars across cosmic time, (ii) the evolution of the ISM and its physical conditions in galaxies, and (iii) how gas drives and inhibits AGN activity.
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All authors Kimberly L. Emig, Sergei Balashev, Francoise Combes, Lucie Cros, Bjorn Emonts, Neeraj Gupta, Antoine Gusdorf, Emmanuel Momjian, Sébastien Muller, Elaine M. Sadler, Pedro Salas, Alexander G. G. M. Tielens, Ilsang Yoon

Cosmology and Nongalactic Astrophysics

Kinetic structure of the intracluster medium across nearby clusters observed with XRISM

Naomi Ota, Erwin T. Lau, Satoshi Yamada et al. (+2 more)

XRISM/Resolve is building a sample of galaxy clusters with directly measured ICM gas motions, revealing diverse projected dynamical states. We compile 45 XRISM/Resolve measurements in 19 nearby galaxy clusters and place them on a common, emission-weighted effective line-of-sight scale, $\ell_{\rm eff}$. We compare the line-of-sight velocity dispersion $\sigma_v$, bulk velocity amplitude $|v_{\rm bulk}|$, their ratio $R_v \equiv |v_{\rm bulk}|/\sigma_v$, and non-thermal pressure proxies. Disturbed non-cool-core systems are not simply higher-dispersion counterparts of relaxed cool-core regions. Instead, differences among cool-core centers, cool-core outer regions, and non-cool-core systems are driven mainly by coherent line-of-sight motion relative to unresolved line broadening: $R_v$ tends to remain below unity in cool-core regions but often exceeds unity in non-cool-core systems, with the mean $R_v$ rising from 0.45 in cool-core centers to 1.6 in non-cool-core systems. These diagnostics help separate local central line broadening, likely associated with AGN feedback in some cool cores, from larger-scale coherent motions associated with sloshing, mergers, and halo assembly. Comparison with forward-modeled TNG-Cluster predictions suggests that many cool-core measurements occupy the lower part of the predicted non-thermal pressure range, consistent with small hydrostatic-mass corrections in relaxed systems and larger corrections in disturbed ones. XRISM is thus beginning to resolve the projected kinetic structure of the ICM across cluster environments, rather than tracing a single sequence of increasing turbulence.
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All authors Naomi Ota, Erwin T. Lau, Satoshi Yamada, Yuki Omiya, Hiroya Yamaguchi

Instrumentation and Methods for Astrophysics

Instrument response generation using high-resolution 3D voxelization of GRBAlpha and VZLUSAT-2 satellites with MEGAlib

Jean-Paul Breuer, Masato Yokota, Yasushi Fukazawa et al. (+24 more)

Pathfinder gamma-ray burst (GRB) detecting CubeSat missions such as GRBAlpha and VZLUSAT-2 have demonstrated the successful application of scintillator detectors with silicon photomultipliers in low Earth orbit (LEO). To produce more comprehensive scientific analysis of the data, the effective area of the detector needs to be characterised at different energies. A large part of this process requires a thorough understanding of the detectors response matrices based on the satellite mass model typically performed through Geant4 and MEGAlib simulations. We use a novel voxelization and binning methodology to turn complex 3D geometries into MEGAlib-compatible versions, and we validate these experiments by showing that the simulation results with Geant4 agree within an order of 10%. We use MEGAlib simulations from various angles around the spacecraft to generate instrumental response matrices for both simple and complex geometries, in the case of GRBAlpha and VZLUSAT-2, respectively.
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All authors Jean-Paul Breuer, Masato Yokota, Yasushi Fukazawa, Hiromitsu Takahashi, Norbert Werner, Jakub Ripa, Marianna Dafcikova, Filip Munz, Masanori Ohno, Balazs Csak, Laszlo Meszaros, Andras Pal, Marcel Frajt, Jan Hudec, Jakub Kapus, Maksim Rezenov, Vladimir Daniel, Juraj Dudas, Petr Svoboda, Hsiang-Kuang Chang, Hao-Min Chang, Chin-Ping Hu, Chih-Hsun Lin, Tsung-Che Liu, Kaustubha Sen, Che-Chih Tsao, Chih-En Wu

Earth and Planetary Astrophysics

The deep atmosphere of Jupiter

Keren Duer-Milner

Jupiter, a rapidly rotating gas giant, features over 20 atmospheric jet streams that penetrate thousands of kilometers into the planet. This work discusses recent progress, identifies key uncertainties regarding the jets' driving and dissipating mechanisms, and suggests future research avenues.
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