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Physics Astrophysics

astro-ph Watch Astrophysics

Tuesday 24 March

Astrophysics of Galaxies

How Massive Can a Population III Starburst Be? Simulating the First Galaxies with High Lyman-Werner Background

Tae Bong Jeong, Alessandra Venditti, Volker Bromm et al. (+4 more)

Observing the first generation of Population~III (Pop~III) stars is one of the most demanding challenges in astronomy. Indeed, Pop~III stars are expected to predominantly form within faint minihalos at early times with a top-heavy initial mass function, resulting in efficient metal enrichment and a fast transition to Pop~II-dominated systems. However, recent surveys with JWST have identified galaxies at the end of the Epoch of Reionization (EoR) with possible signatures of significant Pop~III star formation even at these later times. We here explore the physical conditions required to produce massive Pop~III starbursts during the EoR, using cosmological radiation-hydrodynamic zoom-in simulations. We specifically focus on galaxies with a virial (dynamical) mass of $M_{\rm vir}\approx10^{8}M_{\odot}$ at $7\lesssim z\lesssim8$, i.e., the atomic-cooling halos that could be potential sites for such maximal Pop~III starbursts. In particular, we vary the strength of Lyman-Werner (LW) background radiation up to $J_{\rm LW}\leq10^4J_{21}$, further imposing a high star formation efficiency ($\epsilon_{\rm ff}=1.0$). Our results show that Pop~III starbursts, observable in strongly-lensed survey fields like GLIMPSE, can occur in the presence of a sufficiently high LW flux (with $\gtrsim10^3J_{21}$), leading to delayed, but intense Pop~III star formation. However, even for such high LW fluxes, the Pop~III starburst mass is limited to $M_{\star,\rm Pop~III}<10^6M_{\odot}$, as strong internal metal enrichment occurs after the first Pop~III supernova explosions within the simulated galaxies. While the conditions favoring observable Pop~III starbursts are expected to be rare, we anticipate that future and ongoing large-volume surveys leveraging gravitational lensing will detect multiple cases of Pop~III starbursts in the EoR.
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All authors Tae Bong Jeong, Alessandra Venditti, Volker Bromm, Myoungwon Jeon, Tiger Yu-Yang Hsiao, Steven L. Finkelstein, John Chisholm

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

Astrophysical aspects of string compactifications

Mario Ramos-Hamud

A generic aspect of low-energy effective field theories (EFTs) coming from string compactifications is the appearance of moduli fields. Among these moduli, the axion and dilaton are present as (pseudo-) Goldstone bosons from the spontaneous breaking of an exact (or approximate) global symmetry. These moduli have a different microscopic coupling to matter but appear kinetically coupled in such a way that their interaction can compete with gravity at low energies and have an important effect in strong gravity environments. In this talk, we will discuss some of the astrophysical implications of a stringy-inspired multi-scalar-tensor theory. In particular, we show the numerical solution of the Tolman-Oppenheimer-Volkov (TOV) system of equations, necessary to probe the existence of a screening mechanism that reduces the Brans-Dicke dilaton coupling to macroscopic matter sources such as a neutron star.
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Solar and Stellar Astrophysics

Impact of stellar rotation on type II supernova progenitor masses from pre-explosion imaging

L. Martinez, O. G. Benvenuto and M. A. De Vito

The initial masses of red supergiant (RSG) type II supernova (SN II) progenitors are commonly inferred from pre-explosion imaging by converting the progenitor luminosity into an initial mass estimate using non-rotating stellar evolution models. However, stellar rotation affects the evolution and may influence these estimates. We investigate how the observed distribution of rotational velocities in massive stars influences the progenitor initial masses of SNe II inferred from pre-SN imaging. We compare initial mass estimates obtained from non-rotating models with those derived from rotating models, where the initial rotational velocities of the stellar models are sampled from the observed distribution. We analyse the inferred progenitor initial masses by (i) comparing the results for each SN individually, (ii) examining the overall probability density function, (iii) constructing the cumulative distribution function, and (iv) determining the upper initial-mass boundary. In all cases, the distributions obtained from rotating models are slightly shifted towards lower masses, although the differences remain smaller than the typical uncertainties. When using the observed distribution of initial rotational velocities for massive stars, we infer an upper initial-mass limit for SN II progenitors of 20.4$^{+2.3}_{-1.9} M_{\odot}$. Taken together, these analyses demonstrate that stellar rotation has only a modest impact on progenitor mass estimates from pre-SN imaging within the current observational and model uncertainties when the observed distribution of initial rotational velocities is taken into account. Therefore, adopting this distribution leads to small differences compared to non-rotating models.
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Cosmology and Nongalactic Astrophysics

Identification of low redshift groups and clusters of galaxies in the X-CLASS survey and the X-ray luminosity-temperature relation

Q. Moysan, F. Sarron, N. Clerc et al. (+16 more)

Properties of the hot intracluster and intragroup medium are mostly set by the underlying gravitational potential well, although complex astrophysical processes at play during their buildup may leave a significant imprint. Observational constraints on the degree and scales of such non-gravitational processes require well-selected samples of objects and deep observations of their gas content. We aim to study the scaling relation between two global properties of the hot gas, namely its soft-band X-ray luminosity ($L_X$) and its temperature ($T$), by studying a sample of low-mass systems associated with precise redshifts, simultaneously accounting for sample selection biases and associated measurement uncertainties. This work takes as input a large catalogue of X-ray-selected galaxy clusters (X-CLASS). We perform a thorough revision of the redshifts of sources using deep photometric data from the Legacy Surveys and our own tailored spectroscopic follow-up of 52 low-redshift systems. We devise a spectroscopically complete sample of 155 low-redshift ($0.07<z<0.2$) systems, and we measure properties of their X-ray emitting gas, with median $\overline{T}=1.7$ keV and median $\overline{L_X}=10^{43}$ erg s$^{-1}$. We infer the relation between $L_X$ and $T$ in a Bayesian framework. Our sample of groups and clusters with median total mass $\sim 6 \times 10^{13}M_\odot$ reveals a relation $L_X-T$ steeper than predicted by the self-similar model, with a slope $B=3.2 \pm 0.1$. This result fits well within recent studies that together indicate a trend of increasing slope with decreasing median halo mass. This work supports a scenario of a stronger decrease in luminosity with decreasing mass in the group regime than for massive galaxy clusters. This effect is possibly due to strong and sustained feedback expelling gas efficiently from their relatively shallower potential wells.
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All authors Q. Moysan, F. Sarron, N. Clerc, G. Soucail, C. Adami, B. Altieri, R. Cabanac, M. Chira, J. Comparat, D. Coia, E. Drigga, E. Gaynullina, A. Khalikova, E. Koulouridis, K. Migkas, M. Molham, L. Paquereau, T. Sadibekova, I. Valtchanov

2603.23195 · 24 Mar · 12+5 pages, 9 figures, Accepted by A&A 20th March 2026, The list of updated redshifts (photometric and spectroscopic) for the full X-CLASS sample and the gas properties of the low redshift sample will be available online. The cluster photometric redshift code presented in the paper photXclus is made publicly available at https://codeberg.org/fsarron/photXclus

Abstract PDF $RDSH ×5$GLXY ×3$BAYS ×1$HALO ×1

Solar and Stellar Astrophysics

Unlocking accretion rate diagnostics for high-mass protostars using JWST/MIRI HI lines

S. D. Reyes-Reyes, H. Beuther, E. F. van Dishoeck et al. (+14 more)

While many aspects of high-mass star formation have been investigated, the accretion onto the central protostars is one of the most fundamental but less explored physical properties. JWST/MIRI offers a unique opportunity to explore tracers of accretion at less-extincted wavelengths (5 to 27 um) than those studied so far. We probe the MIRI (MRS/IFU) capability to detect and resolve atomic Hydrogen (HI) emission lines in such embedded objects, to subsequently estimate accretion luminosities (Lacc) and accretion rates (Macc) for the first time in a sample of high-mass star forming regions at different evolutionary stages. We use dereddened HI line luminosities as tracers of accretion by applying existing line-to-accretion-luminosity relations (Lacc-calibrations). As they were originally established for low-mass Class II objects, we assess their applicability on our sample prior to estimating Macc. The infrared continuum reveals, at much higher spatial resolution than before, the location of new protostars, toward which we detect a handful of HI lines. While a few lines are secure detections, many are tentative. The most commonly detected line is HI 7-6, followed by HI 8-6 and HI 6-5. Assuming that their line fluxes are dominated by accretion, we find that two of the three existing Lacc-calibrations predict excessively high Lacc that largely exceed the corresponding L_bol, and that the third Lacc-calibration still overpredicts Lacc for some sources. Considering the given uncertainties, estimated accretion rates are only tentative. This work demonstrates the great potential of JWST/MIRI to probe HI line emission originated in the innermost regions of high-mass protostars, setting the ground floor for further investigations into accretion. While this project had the ambitious goal of robustly quantifying Macc, we have shed light on what outstanding methodological challenges remain.
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All authors S. D. Reyes-Reyes, H. Beuther, E. F. van Dishoeck, C. Gieser, A. Caratti o Garatti, Ł. Tychoniec, P. J. Kavanagh, P. D. Klaassen, K. Justtanont, L. Francis, V. J. M. Le Gouellec, R. Devaraj, T. P. Ray, Y. Chen, M. G. Navarro, W. R. M. Rocha, M. L. van Gelder

Astrophysics of Galaxies

Tentative Detection of the Glycine Isomer Glycolamide in Hot Molecular Core

Chunguo Duan, Fengwei Xu, Qian Gou et al. (+6 more)

Understanding whether prebiotic molecules can endure and reform through the energetic stages of star formation is essential for tracing the continuity of interstellar chemistry toward life. Glycolamide, an isomer of glycine, was recently detected in the molecular cloud G+0.693-0.027. However, establishing its presence in warm, high-density environments is crucial to evaluate the chemical continuity of amides. Here we report the tentative detection of glycolamide in a hot molecular core, G358.93-0.03 MM1, using ALMA 1 mm observations. Seven unblended or only mildly blended emission lines were identified, yielding an abundance of (1.7$\pm$0.2)$\times 10^{-10}$ relative to H$_{2}$. The comparable formamide/glycolamide and acetamide/glycolamide abundance ratios in both sources suggest a chemically connected amide network across different environments. These results demonstrate that amides can persist and chemically evolve during massive star formation, tracing the chemical continuity from interstellar to protostellar environments.
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All authors Chunguo Duan, Fengwei Xu, Qian Gou, Xuefang Xu, Donghui Quan, Laurent Pagani, Xi Chen, Jun Kang, Jiaxin Du

Astrophysics of Galaxies

Intracluster light is a close tracer of the dark matter halo shape

Adela Fernandez, Yannick Bahé, Nina Hatch et al. (+4 more)

We investigate whether the intracluster light (ICL) can serve as a reliable tracer of the shape of the underlying dark matter (DM) haloes in galaxy clusters. Using the cosmological Hydrangea cluster simulations, we measure the 3D and projected shapes of both components with a shape tensor computed in concentric ellipsoidal shells, out to the virial radius $R_\mathrm{200c}$ for each cluster. The ICL and DM are closely aligned, with their major axes typically offset from each other by $\lesssim$10 degrees. Their axis ratios also match closely, with a typical difference of only $\approx\! 0.07$ for both the major-to-minor and major-to-intermediate axes, the DM being slightly rounder than the ICL. These trends are consistent across 2D and 3D measurements and agree well with results from isophotal fitting of mock images. In detail, the axis ratio offset is sensitive to the method used to remove satellites, and may also depend on the choice of subgrid physics models. We demonstrate that the ICL traces the DM shape better than the distribution of satellite galaxies, which exhibits larger scatter in the axis ratio and misalignment angle and is overall more elliptical. Together, these results indicate that the ICL can act as a useful proxy for DM halo ellipticity and orientation.
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All authors Adela Fernandez, Yannick Bahé, Nina Hatch, Joseph Butler, Tutku Kolcu, Garreth Martin, Mireia Montes

High Energy Astrophysical Phenomena

The Persistent Radio Sources and Multi-wavelength Counterparts of Fast Radio Bursts in Massive Binary Systems

Z. Y. Zhao, Q. Wu, F. Y. Wang et al. (+1 more)

Fast radio bursts (FRBs) are millisecond-duration pulses originating from cosmological distances. Multi-wavelength counterparts associated with FRBs are important for unveiling their physical origins. Recent observations provide strong evidence that the sources of some active FRBs are residing in massive star binaries. In this paper, we study the electromagnetic counterparts of FRBs, including persistent radio sources (PRSs) and multi-wavelength emission from magnetar wind nebulae (MWNe) or bow shocks in massive binary systems. We find that the PRSs with luminosity $10^{38}-10^{39}$ erg s$^{-1}$ can be generated by young MWN. The age of magnetars is a few decades. The observed long-term variation of flux density for PRSs can be explained by the internal magnetic field decay of magnetars. The bow shock radiation can account for the less luminous PRS with the luminosity $\lesssim 10^{36}$ erg s$^{-1}$. Magnetically powered nebulae may yield detectable keV synchrotron self-Compton (SSC) X-rays out to $\lesssim 20$ Mpc, whereas rotation-powered systems mainly produce GeV SSC emission detectable only within $\lesssim 0.1$ Mpc. For active magnetars in massive binaries, enhanced wind interaction can generate synchrotron X-rays detectable within $\lesssim 50$ Mpc and GeV-TeV inverse-Compton emission detectable within $\lesssim 1-0.1$ Mpc.
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All authors Z. Y. Zhao, Q. Wu, F. Y. Wang, Z. G. Dai

Solar and Stellar Astrophysics

Anomalously Strong Localized First Ionization Potential Effect Associated with a Solar Subflare

Man-Hei Ng, Xiaoping Zhang and P. F. Chen

Plasma composition in the solar corona commonly differs from that of the photosphere, with the enhancement of low–first-ionization-potential (FIP) elements referred to as the FIP effect. This phenomenon provides important diagnostics of energy and mass transport between different layers of the solar atmosphere. In this work, we analyze an anomalously strong, localized FIP effect observed in active region 13486 associated with a subflaring episode on 2023 November 17, using multiwavelength observations combining high energy-resolution soft X-ray disk-integrated spectra obtained by the Macao Science Satellite-1B with spatially resolved EUV/UV and H$\alpha$ imaging from Hinode/EIS, SDO/AIA and HMI, and CHASE/HIS. By investigating the temporal evolution of plasma composition in response to changes in magnetic field orientation, we provide new insight into the physical processes linking magnetic reconnection, ponderomotive force fractionation, and coronal abundance anomalies. This work reveals that the anomalously strong enhancement of low-FIP elements is localized in regions with strongly inclined magnetic fields despite a subflare. We interpret these observations within the framework of the ponderomotive force fractionation model and propose that the inclined magnetic geometry enhances the transmission of upward-propagating magnetohydrodynamic waves by reducing reflection near the plasma-$\beta$$\simeq$1 layer, enhancing FIP fractionation associated with a consequential upward-directed ponderomotive force. In addition, sustained chromospheric heating associated with chromospheric reconnection and flux cancellation appears to maintain the enhanced FIP effect for tens of minutes following the event.
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Instrumentation and Methods for Astrophysics

A High-frequency Geodetic VLBI Experiment for Optical Clock Comparison

Monia Negusini, Myoung-Sun Heo, Cecilia Clivati et al. (+40 more)

An intercontinental metrological clock comparison between Italy and the Republic of Korea was performed by means of geodetic K-band VLBI observations. The comparison involved the hydrogen masers (H-masers) used at Medicina and Sejong radio telescopes. The same clocks were simultaneously compared by a satellite link and by high-precision optical clocks maintained at the National Metrology Institutes, KRISS in Korea and INRIM in Italy, and delivered to VLBI antennas via optical fiber. The H-masers frequency difference was estimated by extrapolating the clock rate from VLBI data using two geodetic VLBI software. This was subsequently compared with clock differences derived by satellite link and by local optical clocks. Results obtained with different approaches were in agreement at the level of $10^{-15}$ s/s. This pilot study demonstrates that standard high-frequency (K-band) geodetic VLBI campaigns could be a viable approach to conduct intercontinental clock comparisons, now only possible via satellite links. This uncertainty can be reduced thanks to the planned installation of new-generation, broadband, high-frequency receivers on the involved telescopes. K/Q/W-band geodetic observations will allow an improvement of the accuracy of the resulting group delays through broad bandwidth synthesis from 20 to 100 GHz. Furthermore, the Frequency Phase Transfer (FPT) method will also be explored together with the use of PCAL systems installed at the radio telescopes to improve phase stability and thus allow a better estimation of the station clock parameters.
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All authors Monia Negusini, Myoung-Sun Heo, Cecilia Clivati, Shuangjing Xu, Roberto Ricci, Taehyun Jung, Buseung Cho, Matteo Stagni, Claudio Bortolotti, Giuseppe Maccaferri, Federico Perini, Mauro Roma, Do-Young Byun, Do-Heung Je, Marco Pizzocaro, Davide Calonico, Elena Cantoni, Giancarlo Cerretto, Stefano Condio, Giovanni A. Costanzo, Simone Donadello, Irene Goti, Michele Gozzelino, Alberto Mura, Filippo Levi, Matias Risaro, Huidong Kim, Won-Kyu Lee, Chang Yong Park, Dai-Hyuk Yu, Young Kyu Lee, Joon Hyo Rhee, Chanjin Park, Minseong Lee, Hyo Ryoung Kim, Sung-Moon Yoo, Jungho Cho, Jongsoo Kim, Sang-Oh Yi, Ha Su Yoon, Pablo de Vicente, Javier González, Cristina García Miró

Astrophysics of Galaxies

The time-delay model and its applications to galactic archaeology

Francesca Matteucci

The time-delay model is the way we interpret the diagram [X/Fe] vs. [Fe/H], where X is the abundance of a generic element from carbon to uranium. This interpretation is based on the lifetimes of stars of different masses producing different elements. The abundance of Fe ([Fe/H]) traces the "stellar metallicity" and is due to supernovae Type Ia, which are believed to be the major producers of Fe, and in part to supernovae core-collapse. In particular, if X is an alpha-element, produced on short timescales from massive stars, the ratio [alpha/Fe] will show an overabundance of the alpha-elements relative to Fe at low metallicity. In fact, the bulk of Fe is produced with a time delay relative to alpha-elements, since Type Ia supernovae are white dwarfs in binary systems and they can have lifetimes as long as the age of the Universe. In this paper, I will show how powerful is the time-delay model in order to interpret the abundance patterns observed in stars and interstellar gas, since it allows us to put constraints on stellar nucleosynthesis as well as on the star formation histories of galaxies. I will present some applications of the time-delay model, in particular to the chemical evolution of the Milky Way and galaxies of different morphological type as well as to the identification of high redshift objects by means of their abundances.
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Cosmology and Nongalactic Astrophysics

Low-Frequency Stochastic Gravitational-Wave Background in Gaia DR3 catalog

V. Akhmetov, L. Filipello, M. Crosta et al. (+4 more)

We investigate the potential to detect low-frequency gravitational waves (GWs) through their imprints on the proper motions of distant quasars observed by the Gaia mission. Using astrometric data from Gaia DR3, we simulate the effect of GWs on the proper motions of quasars, incorporating their actual sky positions and measurement uncertainties. We investigate two closely related data analysis techniques for the extraction and characterization of GW signals from quasar proper motions: Vector Spherical Harmonics (VSH) and angular correlation functions, commonly referred to as Hellings-Downs curves (HDC). Using realistic simulated data, we forecast their sensitivity and accuracy to GWs, and evaluate the impact of systematic errors. From these simulations, we derive an upper limit on the amplitude of a stochastic GW background, constrained by the observational timespan, astrometric precision, and the sky distribution of quasars. VSH decomposition appears less sensitive to uneven sky sampling and anisotropic noise. The HDC approach retains a larger fraction of the pairwise correlation information and therefore exhibits higher raw statistical sensitivity under idealized conditions. We find that, with Gaia DR3 proper motion errors, the lower limit for a detectable GW strain is of 10^{-11}, with possible improvements to about 3 x 10^{-12} for the next Gaia Data Release 4 (for the same number of quasars). This limit holds for a stochastic GW spectrum integrated over all frequencies less than half the inverse of the 34-month observational timespan of Gaia DR3, corresponding to approximately 5.6 nHz. We also investigate how different data-restriction and weighting schemes influence the final estimate of the gravitational wave strain.
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All authors V. Akhmetov, L. Filipello, M. Crosta, M. G. Lattanzi, B. Bucciarelli, U. Abbas, F. Santucci

Cosmology and Nongalactic Astrophysics

Revisiting Constraints on Primordial Curvature Power Spectrum from PBH Abundances

Ashu Kushwaha and Teruaki Suyama

Primordial black holes (PBHs) can form in the early Universe, during radiation domination, from the collapse of large-amplitude density perturbations shortly after horizon re-entry. This mechanism establishes an approximate one-to-one correspondence between the PBH mass and the scale of the peak in the primordial curvature perturbations. Consequently, the constraints on PBH abundances can be translated into upper limits on the amplitude of the primordial curvature power spectrum, providing an indirect probe of the last e-folds of inflation corresponding to these smaller scales. We derive constraints on the amplitude of primordial curvature power spectra with both narrow and broad peaks using up-to-date bounds on PBH abundances. Given the theoretical uncertainties in PBH formation, we systematically compare the constraints obtained using the Press-Schechter (PS) formalism and peak theory, accounting for the nonlinear relation between curvature perturbations and density contrast, and assess the impact of different window functions and the transfer function. We quantify the impact of spherical versus nonspherical collapse criteria and show that including non-sphericity significantly increases the inferred amplitude of the primordial power spectrum, reflecting the larger threshold density contrast required for PBH formation. We also find that whereas the constraints obtained using the PS formalism and peak theory remain largely similar for the monochromatic case, they differ in the case of a broad primordial power spectrum. This discrepancy underscores that current constraints remain sensitive to the choice of statistical formalism. Our consistent treatment of monochromatic and extended mass functions provides a systematic mapping based on existing methodologies, while highlighting that reducing these theoretical uncertainties is a crucial step toward probing the early Universe through PBHs.
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Solar and Stellar Astrophysics

3D NLTE Sodium abundances in late-type stars. Abundance corrections and synthetic spectra

G. Canocchi, E. X. Wang, A. M. Amarsi et al. (+2 more)

Neutral sodium is an important tracer of the Galactic chemical evolution, a powerful diagnostic of different stellar populations, and the subject of detailed studies of exoplanet atmospheres via transmission spectroscopy. This work aims to study and quantify the errors in stellar analyses of Na I lines caused by the use of one-dimensional (1D) hydrostatic model atmospheres and the assumption of local thermodynamic equilibrium (LTE). We studied the line formation of nine Na I lines in FGK dwarfs and giants via, for the first time, 3D non-LTE (NLTE) radiative transfer post-processing with the code Balder on 3D radiation hydrodynamic stellar atmospheres from the Stagger grid spanning Teff= 4000 to 6500 K, log g = 1.5 to 5.0, and [Fe/H]=-4 to +0.5. We find that the 3D NLTE abundance corrections relative to 1D LTE tend to be negative, and more positive than the corresponding 1D NLTE corrections. This reflects more efficient overionisation in the steeper temperature gradient of the 3D models. The corrections are typically less severe than -0.1 dex for weak lines, but become much larger for saturated lines in low-gravity giants (log g < 2.0), even reaching -0.7 dex. However, for the D resonance lines, the 3D NLTE corrections relative to 1D LTE become slightly positive at the lowest metallicities in our grid, typically around +0.05 dex at [Fe/H]=-4. We make our 3D NLTE grid, together with interpolation routines based on radial basis functions and fully connected feedforward neural networks, publicly available. This will enable more accurate determination of sodium abundances in present and forthcoming stellar spectroscopic surveys, particularly for metal-poor stars, as well as a better characterisation of the Na I D lines in exoplanet atmospheres.
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All authors G. Canocchi, E. X. Wang, A. M. Amarsi, K. Lind, M. Racca

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

Cosmic Ray Boosted Dark Matter in COSINUS: Modeling and Constraints

G. Angloher, M. R. Bharadwaj, A. Böhmer et al. (+41 more)

Direct detection of nuclear recoils due to sub-GeV dark matter is challenging because of the small kinetic energy of the light dark matter particles. Although limits down to a few hundred MeV have been reached using specially designed low threshold detectors, further improvements are now constrained more by background event rates than by energy thresholds. However, constraints down to sub-MeV dark matter masses can still be obtained through the boosted dark matter framework. In this scenario, high-energy cosmic rays or neutrinos scatter off dark matter particles, imparting additional kinetic energy and boosting them beyond the typical velocities expected from the non-relativistic dark matter halo. These boosted dark matter particles can then be detected even by experiments with higher energy thresholds. In this work, we present a catalog of dark matter - nucleon scattering cross sections corresponding to a heavy mediator limit for spin zero, one half and one dark matter and for scalar and vector mediators with even or odd parity. Based on these results, we present projected constraints on the dark matter - nucleon cross section for the COSINUS experiment, assuming an exposure of 100 kg d, demonstrating the potential sensitivity to sub-GeV boosted dark matter.
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All authors G. Angloher, M. R. Bharadwaj, A. Böhmer, M. Cababie, I. Colantoni, I. Dafinei, N. Di Marco, C. Dittmar, F. Ferella, F. Ferroni, S. Fichtinger, A. Filipponi, T. Frank, M. Friedl, D. Fuchs, L. Gai, M. Gapp, M. Heikinheimo, M. N. Hughes, K. Huitu, M. Kellermann, R. Maji, M. Mancuso, L. Pagnanini, F. Petricca, S. Pirro, F. Pröbst, G. Profeta, A. Puiu, F. Reindl, K. Schäffner, J. Schieck, P. Schreiner, C. Schwertner, P. Settembri, K. Shera, M. Stahlberg, A. Stendahl, M. Stukel, C. Tresca, S. Yue, V. Zema, Y. Zhu, N. Zimmermann

High Energy Astrophysical Phenomena

MAGIC observations of NGC 4278. The first low-luminosity radio galaxy with compact jets detected at TeV energies

S. Abe, J. Abhir, V. A. Acciari et al. (+189 more)

The Large High Altitude Air Shower Observatory (LHAASO) Collaboration has recently reported the first detection at TeV energies of a low-luminosity radio galaxy, NGC 4278. The aim of this work is to investigate the high-energy properties of NGC 4278 during the flaring and subsequent quasi-quiescent states with the Florian Goebel Major Atmospheric Gamma Imaging Cherenkov (MAGIC) telescopes. NGC 4278 is located in the field of view of two blazars, 1ES 1215+303 and 1ES 1218+304, previously observed by the MAGIC telescopes. Therefore, we re-analyzed MAGIC observations made between 2010 and 2024 on these sources. We also modeled the broadband spectral energy distribution of the source during and after the flaring state at TeV energies. We did not detect any statistically significant $\gamma$-ray emission from NGC 4278 with MAGIC. The corresponding upper limits obtained using the entire MAGIC dataset ($F_{{\rm UL, }\, >150\, \mathrm{GeV}}=1.5 \times 10^{-12}\, \mathrm{ph \, s^{-1}\, cm^{-2}}$) are consistent with the LHAASO results. The best-fit models obtained for both emission states suggest that the emitting region is strongly particle-dominated, and an efficient acceleration mechanism has to be in action in order to reach TeV energies. The transition between the flaring and quasi-quiescent state cannot be explained by a simple radiative cooling of the emitting particles. The inferred jet power, of the order of $L_{\rm jet}\sim 10^{42}\, \mathrm{erg\,s^{-1}}$, is dominated by the kinetic component in both states and it is in a good agreement with previous, time-averaged observational estimates, supporting the idea that such high-energy flares might be recurrent. The jet, however, remains too weak to break the host-galaxy confinement.
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All authors S. Abe, J. Abhir, V. A. Acciari, A. Aguasca-Cabot, I. Agudo, T. Aniello, S. Ansoldi, L. A. Antonelli, A. Arbet Engels, C. Arcaro, T. T. H. Arnesen, A. Babić, C. Bakshi, U. Barres de Almeida, J. A. Barrio, L. Barrios-Jiménez, I. Batković, J. Baxter, J. Becerra González, W. Bednarek, E. Bernardini, J. Bernete, A. Berti, J. Besenrieder, C. Bigongiari, A. Biland, O. Blanch, G. Bonnoli, Ž. Bošnjak, E. Bronzini, I. Burelli, A. Campoy-Ordaz, A. Carosi, R. Carosi, M. Carretero-Castrillo, A. J. Castro-Tirado, D. Cerasole, G. Ceribella, A. Cerviño, A. Chilingarian, A. Cifuentes Santos, J. L. Contreras, J. Cortina, S. Covino, F. D'Ammando, G. D'Amico, P. Da Vela, F. Dazzi, A. De Angelis, B. De Lotto, R. de Menezes, J. Delgado, C. Delgado Mendez, F. Di Pierro, R. Di Tria, L. Di Venere, A. Dinesh, D. Dominis Prester, D. Dorner, M. Doro, L. Eisenberger, D. Elsaesser, L. Fariña, L. Foffano, L. Font, S. Fröse, Y. Fukazawa, R. J. García López, S. García Soto, S. Gasparyan, M. Gaug, J. G. Giesbrecht Paiva, N. Giglietto, F. Giordano, P. Gliwny, T. Gradetzke, R. Grau, J. G. Green, P. Günther, D. Hadasch, A. Hahn, G. Harutyunyan, T. Hassan, L. Heckmann, J. Herrera Llorente, D. Hrupec, D. Israyelyan, J. Jahanvi, I. Jiménez Martínez, J. Jiménez Quiles, J. Jormanainen, S. Kankkunen, T. Kayanoki, P. M. Kouch, G. Koziol, H. Kubo, J. Kushida, M. Láinez, A. Lamastra, E. Lindfors, S. Lombardi, F. Longo, R. López-Coto, M. López-Moya, A. López-Oramas, S. Loporchio, L Lulić, P. Majumdar, M. Makariev, G. Maneva, M. Manganaro, S. Mangano, S. Marchesi, M. Mariotti, M. Martínez, P. Maruševec, D. Mazin, S. Menchiari, J. Méndez Gallego, S. Menon, D. Miceli, R. Mirzoyan, M. Molero González, E. Molina, H. A. Mondal, A. Moralejo, C. Nanci, A. Negro, V. Neustroev, M. Nievas Rosillo, C. Nigro, L. Nikolić, K. Nilsson, S. Nozaki, A. Okumura, J. Otero-Santos, S. Paiano, D. Paneque, R. Paoletti, J. M. Paredes, M. Peresano, M. Persic, M. Pihet, G. Pirola, F. Podobnik, P. G. Prada Moroni, E. Prandini, W. Rhode, M. Ribó, J. Rico, A. Roy, N. Sahakyan, F. G. Saturni, K. Schmitz, F. Schmuckermaier, T. Schweizer, A. Sciaccaluga, G. Silvestri, A. Simongini, J. Sitarek, D. Sobczynska, A. Stamerra, J. Strišković, D. Strom, M. Strzys, Y. Suda, H. Tajima, M. Takahashi, R. Takeishi, J. Tartera Barberà, P. Temnikov, T. Terzić, A. Tutone, S. Ubach, J. van Scherpenberg, M. Vazquez Acosta, S. Ventura, G. Verna, I. Viale, A. Vigliano, C. F. Vigorito, E. Visentin, V. Vitale, I. Vovk, R. Walter, C. Walther, F. Wersig, M. Will, P. K. H. Yeung, E. Torresi, G. Migliori, P. Grandi

Astrophysics of Galaxies

How well does MAGPHYS recover galaxy properties? A test using EAGLE simulated star-forming galaxies

Zoe R. Jones, Elisabete da Cunha and Andrew Battisti

Spectral energy distribution (SED) models are widely used to infer the physical properties of galaxies from multi-wavelength photometry, but their accuracy is difficult to assess because the true properties of observed galaxies are generally unknown. We address this by fitting synthetic SEDs of ~31,000 star-forming galaxies drawn from the EAGLE cosmological simulations, post-processed with the SKIRT radiative transfer code, using the MAGPHYS SED modelling framework. This provides a controlled testbed with known intrinsic parameters, enabling a direct assessment of model accuracy and the origin of systematic biases. Under idealised conditions, fitting well-sampled ultraviolet-to-submillimetre SEDs at z=0.1, z=2, and z=5, MAGPHYS recovers stellar mass, star formation rate, specific star formation rate, dust mass, and dust luminosity to within <~0.14 dex, while mass-weighted stellar ages are not robustly constrained. We find that mismatches between the assumed star formation history (SFH) priors and the intrinsic SFHs of the simulated galaxies introduce systematic biases in stellar mass estimates, even when the fits provide good statistical agreement. To assess performance under realistic survey conditions, we construct a WAVES-like mock sample using optical and near-infrared photometry with realistic uncertainties. In this case, stellar masses and star formation rates remain well constrained (systematic offsets <~0.1 dex; scatters ~0.07 and ~0.15 dex, respectively), whereas dust properties degrade significantly without far-infrared data: dust luminosities show offsets of ~0.30 dex and scatters ~0.25 dex, and dust masses exhibit scatters ~0.3 dex. We conclude that MAGPHYS is a reliable tool for recovering key galaxy properties from broad-band photometry, but that SFH assumptions and limited wavelength coverage introduce significant uncertainties, particularly for dust and stellar ages.
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Astrophysics of Galaxies

Extinction curves, extinction laws, and the failure of interstellar dust models

Frederic Zagury

The interpretation of ultraviolet Galactic interstellar extinction curves is obscured today by accumulated assumptions, such as a purported link between the 2200 A bump and metallicity, that are not firmly supported by observations. In this paper I define extinction curves as the ratio F*/F0 of the near-infrared-to-ultraviolet spectrum of a reddened star to that of the same star without intervening material, rather than in terms of a magnitude difference, and revisit their observed properties. Special attention is given to the connection that Galactic extinction curves with a 2200 A bump retain with the ultraviolet extrapolation of the exponential extinction law defined by their near-infrared-to-optical segment. This connection leads to the classification of all extinction curves into three types. A graphical representation of these types together with their underlying exponential extinction laws demonstrates that interstellar extinction curves can be interpreted in two ways. Either they result from the mixing of distinct extinction laws associated with different particles, as traditionally assumed, or Galactic ultraviolet curves with a bump are not extinction laws proper but instead deviate from a universal exponential extinction law owing to an additional contribution from coherently forward-scattered starlight. Given the observational constraints on the interpretation of extinction curves, such as their dependence on just two parameters, and the fact that bump-like extinction curves are barely observed outside the Galaxy, the latter interpretation emerges as the only logically consistent one.
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Solar and Stellar Astrophysics

Quasiperiodic Slipping Motion of Flare Ribbon Fine Structures Anchored in a Sunspot Light Bridge

Tianyuan Chen, Xiaoli Yan, Zhike Xue et al. (+9 more)

We used high-resolution observations from the New Vacuum Solar Telescope and the Solar Dynamics Observatory to carry out a detailed multiwavelength analysis of the fine structures in the flare ribbon of a C3.9-class flare on 22 April 2021. A segment of the flare ribbon was rooted in a sunspot light bridge and exhibited discrete substructures, which we term "burrs", with equivalent diameters of 233-895 km and inter-core separations of 1129-1739 km. These structures are characterized by discrete redshifted cores accompanied by "tails" with lengths of 700-1370 km and widths of 310-600 km that show faint blueshifts. The burrs display systematic slipping motions along the ribbon, with apparent velocities decreasing from about 40 to 21 km/s, and show a distinct quasi-periodicity of about 6 minutes in H-alpha and EUV passbands. Differential emission measure analysis indicates that the emitting plasma is multi-thermal and dominated by temperatures of 1-2 MK. The observed morphology and kinematics are consistent with impulsive energy deposition by precipitating plasmoids, or oblique flux ropes, produced by tearing-mode fragmentation in the coronal current sheet. The close spatiotemporal association between the tails and blueshifts supports the interpretation that these features are related to untwisting magnetic flux ropes. The approximately 6-minute periodicity further suggests that the reconnection process may be modulated by photospheric p-mode oscillations coupled with tearing-mode instability. These results provide observational evidence that light-bridge-anchored fine structures can act as elementary units of flare energy release.
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All authors Tianyuan Chen, Xiaoli Yan, Zhike Xue, Jincheng Wang, Zhe Xu, Liheng Yang, Yadan Duan, Yian Zhou, Zongyin Wu, Qifan Dong, Guotang Wu, Xinsheng Zhang

Solar and Stellar Astrophysics

Orbital motion detected in gamma Cas Fe K emission lines

Yael Naze, Masahiro Tsujimoto, Gregor Rauw et al. (+1 more)

A subset of Be stars, typified by the naked-eye star gamma Cas, exhibits unusually bright and hard X-ray emission, the origin of which has remained debated for five decades. We performed high-resolution X-ray spectroscopic monitoring of gamma Cas with the Resolve instrument aboard the X-Ray Imaging and Spectroscopy Mission (XRISM). X-ray lines from the ultra-hot plasma and fluorescence from cooler material exhibit Doppler shifts consistent with orbital motion, not of the Be star itself, but of its low-mass companion (previously shown to be a white dwarf). This first evidence of orbital motion for the hard X-ray emitting plasma uniquely links it to the scenario of accretion onto the white dwarf companion. The modest line broadening further indicates that fluorescence occurs on the white dwarf surface and excludes X-ray generation in the inner parts of an accretion disc. Our findings identify gamma Cas and its analogues as the previously elusive, but long predicted class of binaries composed of a Be and a white dwarf. Identifying the origin of the hard X-rays from gamma Cas and its analogues, which represent about 10% of early-type Be stars, provides a key input for population synthesis models of massive binary evolution.
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All authors Yael Naze, Masahiro Tsujimoto, Gregor Rauw, Sean J. Gunderson

Astrophysics of Galaxies

The Fate of the Milky Way–Andromeda System: To Merge or Not?

Hao Wu, Yang Huang, Huawei Zhang et al. (+2 more)

It has long been predicted that the Milky Way (MW) will eventually merge with Andromeda (M31), a view reinforced by HST measurements indicating a small M31 transverse velocity. However, using updated Gaia-based proper motions (PMs) and including the dynamical influence of the Large Magellanic Cloud (LMC) and M33, Sawala et al. reported an MW–M31 merger probability of $\sim$50% within 10 Gyr, leaving the fate of the Local Group (LG) uncertain. Adopting their semi-analytic framework, we revisit this problem with the latest and most precise Gaia-based PMs for M31 and M33, corrected for systematic offsets in Gaia astrometry. In our fiducial model, the MW–M31 merger probability rises to 90%, with a median merger time of $6.5_{-1.5}^{+1.3}$ Gyr, broadly restoring the classical picture. A sensitivity analysis shows that the merger probability depends strongly on the adopted M31 PM through two channels: a direct effect via the radial-tangential balance of the MW-M31 orbit, and a satellite-mediated effect, where the M31 PM fixes the orbital plane and determines how satellite-induced barycentric reflex motions project onto it, either promoting or suppressing a merger. Given this sensitivity, current measurements, while favoring a high merger probability, remain inconclusive, spanning from 64.7% to 100% across the 2$\sigma$ PM region. Future PM measurements with uncertainty of $\lesssim2\,\upmu\mathrm{as\,yr^{-1}}$ will be required to reach a firm conclusion, i.e., to constrain the probability range within 10% at the 2$\sigma$ level.
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All authors Hao Wu, Yang Huang, Huawei Zhang, Guangze Sun, Shi Shao

Cosmology and Nongalactic Astrophysics

Probing the Bias of Large-Scale Structure with Unlocalized Fast Radio Bursts

Yu-Tong Su and Zhengxiang Li

Large-scale structure (LSS) and tracer bias connect observable populations to the cosmic matter distribution. While galaxies are standard tracers, transient events such as gravitational-wave sources can also probe LSS despite large localization uncertainties. Fast radio bursts (FRBs), owing to their cosmological distances and dispersion-measure information, provide a promising complementary tracer of LSS. However, most FRBs lack precise localization and redshift measurements, introducing severe angular and radial errors that dilute the clustering signal. Here we construct an end-to-end framework to infer the linear large-scale bias of unlocalized FRB populations using the isotropic two-point correlation function. Our pipeline adopts the Landy-Szalay estimator with noise-matched random catalogs, a Monte Carlo forward model accounting for localization smearing, and likelihood-based inference with covariance matrices from lognormal mock samples. We test the method on synthetic FRB samples at redshifts z=0.3, 0.5, and 0.7 with injected bias values b=1.2, 1.5, and 2.0. The measured correlation functions closely follow smeared theoretical predictions, confirming that positional uncertainty dominates clustering suppression. Despite sample variance, the inferred bias posteriors recover the true inputs and preserve relative bias ordering. Discrimination is strongest at low redshift and weakens at higher redshift, where low-bias populations become poorly constrained. Our results demonstrate that meaningful large-scale clustering information can be extracted from poorly localized FRBs when smearing effects are properly modeled, establishing a practical route for future FRB-based LSS investigations.
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Cosmology and Nongalactic Astrophysics

Enhancing cosmological constraints with nonlinear tanh transformations of Hermite-Gaussian Derivative fields

Zhiwei Min, Ye Ma, Zhujun Jiang et al. (+4 more)

A key goal in large-scale structure analysis is to extract multi-scale information to improve cosmological parameter constraints. In particular, higher-order derivative fields are especially valuable as they capture the geometric and topological information of the cosmic web that is highly sensitive to cosmological parameters. Traditional derivative-based methods, such as finite-difference or Fourier approaches, suffer from noise amplification at small scales and cannot stably capture multi-scale features. We present a robust two-step framework: first, stable multi-scale arbitrary-order derivatives are obtained via Hermite-Gaussian convolutional filters that suppress small-scale noise; second, a tanh nonlinear transformation compresses extreme density contrasts and enhances the visibility of cosmic web structures. Using the Quijote simulations, we show that combining multi-scale first-order spectra yields improvements of 1.2-3.0 times across all seven cosmological parameters, while multi-order spectra at a fixed scale provide 1.3-2.9 times gains. The most comprehensive combination achieves nominal gains of 2.0-5.3 times. Our method offers a robust approach to extracting additional cosmological information for future surveys.
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All authors Zhiwei Min, Ye Ma, Zhujun Jiang, Jiacheng Ding, Fenfen Yin, Le Zhang, Xiaodong Li

Earth and Planetary Astrophysics

Sometimes You Just Can't Put a Ring on It: Setting Constraints on Rings around Moons from Magnetic Fields

Jamie M. Erak and Mor Rozner

All four giant planets and several minor bodies in the Solar System host rings. However, rings around moons have yet to be observed. A host planet can produce magnetic fields that affect its moons, adding a wealth of dynamical phenomena that could shape the properties of such ring systems. In this study, we investigate constraints on the stability of circumsatellitial rings (CSRs) under the effect of magnetic fields originating from the host planet, using both analytical and numerical methods. We find that the electric field induced by the rotation of the ambient planetary magnetosphere constitutes a significant perturbation on charged grains in CSRs. We demonstrate that this effect can de-orbit sufficiently charged grains on short timescales, providing a novel approach to constrain the properties of CSRs.
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Solar and Stellar Astrophysics

SGR 1935+2154's Quiet Local Environment: Clues for Its Progenitor

Wenlang He, Ping Zhou and Bingqiu Chen

Magnetars are highly magnetized neutron stars (NSs) whose evolution and radiation are governed by the decay and/or reconfiguration of their magnetic fields. The origin of magnetars remains an open question, with proposed progenitor scenarios including core-collapse (CC) of very massive stars ($\ge 25~M_\odot$) or non-very massive stars ($8<M_*<25~M_\odot$), mergers of stellar systems, and accretion-induced collapse (AIC) of white dwarfs (WDs). Investigating the environments of magnetars can offer valuable clues to this issue. In this work, we study the local (a radius of $0.87^\circ$, $\sim 100$ pc at 6.6 kpc) stellar environment of SGR 1935+2154, which is spatially associated with the supernova remnant (SNR) G57.2+0.8, based on astrometry from Gaia DR3 and multi-band photometry from optical to infrared (IR). We discover that the upper limit of the surface density of massive stars around SGR 1935+2154 is only a quarter of that of the solar neighborhood, where the star formation rate is modest in the Galaxy. This quiet environment implies that the magnetar was likely formed by the CC of either a non-very massive star or a binary merger product rather than the CC of a very massive star. Although alternative channels cannot be excluded, their probabilities may be substantially lower. The studies of magnetars associated with SNRs consistently favor non-very massive progenitors, implying that such progenitors may produce a considerable fraction of magnetars. We also backtrack the trajectories of SGR 1935+2154 and its surrounding stars to search for its potential massive companions, yet no such companions are found.
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Instrumentation and Methods for Astrophysics

A Slit Mask Integral Field Unit for the Robert Stobie Spectrograph on the Southern African Large Telescope: I. Instrument Development

Sabyasachi Chattopadhyay, Matthew A. Bershady, Michael P. Smith et al. (+2 more)

Integral field spectroscopy (IFS) has been added as a new observation mode to the Robert Stobie Spectrograph (RSS), the workhorse multi-mode instrument on the Southern African Large Telescope. RSS operates as an imaging spectrograph covering 320-900 nm with a spectral resolution–slit-width product of 6600 arcsec. Using fiber optics and prismatic fold mirrors, we have been able to construct compact integral field units (IFUs) that fit within the same volume as the long-slit cassettes (134 mm x 130 mm x 8 mm). These `slit mask' IFUs (SMIs) direct the telescope beam into a 2D sky-facing fiber array routed in the focal plane dimension into an 8$\arcmin$ 1D pseudo-slit, with fiber output redirected back into the spectrograph collimator. The first completed unit, SMI-200, features 303 object fibers and 24 sky fibers, providing a spatial resolution of 0.8$\arcsec$ (200 $\upmu$m core diameter) over a field of view (FOV) of 22.5$\arcsec$ x 17.6$\arcsec$. This paper describes the specific design considerations and design and fabrication strategies to maximize performance and minimize risk during construction, given the demanding and highly constrained cassette geometry. We also detail mapping and laboratory characterization of the IFU. Laboratory measurements demonstrate a total throughput of 77%, but an effective throughput of only 55-60% within the RSS collimator acceptance beam of f/4.2 due to losses dominated by focal ratio degradation (FRD) induced by sharp bend radii imposed by the tight cassette volume.
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All authors Sabyasachi Chattopadhyay, Matthew A. Bershady, Michael P. Smith, Antoine Mahoro, Marsha J. Wolf

Astrophysics of Galaxies

HI Gas and Star Formation in Major Galaxy Pairs from the FAST All-Sky HI Survey (FASHI)

Shulan Yan, Qingzheng Yu, Taotao Fang et al. (+6 more)

Atomic hydrogen (HI) plays a fundamental role in fueling star formation in galaxies. However, the behavior of HI gas in interacting systems, particularly galaxy pairs, remains elusive. In this work, we investigate the HI content of major mergers by cross-matching the extragalactic HI catalog from the FAST All-Sky HI Survey (FASHI) with a previously established sample of isolated galaxy pairs. With the superior sensitivity of FAST, we have constructed the largest sample of major mergers with HI detections, consisting of $440$ galaxy pairs: $364$ spiral-spiral (S+S) and $76$ spiral-elliptical (S+E) systems. We examine the HI gas fraction ($f_{\mathrm{HI}}$), star formation rate (SFR) and HI star formation efficiency ($\mathrm{SFE_{HI}}=\mathrm{SFR}/M_{\rm HI}$) for individual galaxies in pairs. The control sample is matched in both stellar mass and redshift. We find that paired galaxies, particularly those in pairs with small projected separations ($d_{\mathrm{p}}<50\ h^{-1}\mathrm{kpc}$), exhibit systematically lower (by $8.8\%$) HI gas fractions compared to the control galaxies. The SFR is enhanced for galaxies in S+S pairs. $\mathrm{SFE_{HI}}$ is $\sim15\%$ higher for galaxies in S+S pairs than in the control galaxies, while spiral galaxies in S+E pairs show no significant difference in $\mathrm{SFE_{HI}}$ compared to the control sample. These findings suggest that the merging process triggers efficient HI gas depletion and enhances star formation, especially in close S+S pairs. Notably, our sample includes $26$ red spirals in paired systems. These galaxies exhibit HI deficiency and suppressed star formation activity compared to the isolated galaxies, indicating that interactions may affect quiescent spirals differently, potentially due to mechanisms similar to ellipticals.
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All authors Shulan Yan, Qingzheng Yu, Taotao Fang, Chuan He, Andrew Ma, Junfeng Wang, C.Kevin Xu, Ming Zhu, Weishan Zhu

Cosmology and Nongalactic Astrophysics

Cluster Infall for Mass Calibration in the Stage-IV Era

Connor Sweeney and Eduardo Rozo

The outskirts of galaxy clusters present a promising avenue for constraining cluster masses in a way that is robust to the impact of baryonic physics. We assess the accuracy to which the cluster infall regions can be used for cluster mass calibration. Building on previous work, we parameterize the velocity distribution $P(v_{\rm r},v_{\rm tan}|r,M)$ of dark matter halos on scales $r \geq 5\ h^{-1}\ \rm{Mpc}$ as the product of the marginalized distribution $P(v_{\rm r}|r,M)$ and the conditional distribution $P(v_{\rm tan}|v_{\rm r},r,M)$, calibrating the radial and mass dependence of these distributions in numerical simulations. We then project our model along the line-of-sight to obtain accurate predictions for the distributions of line-of-sight velocities at a given projected radius and cluster mass $P(v_{\rm LOS}|R,M)$, which we can observe with spectroscopic survey data. With our model, we forecast that spectra from the Dark Energy Spectroscopic Instrument (DESI) can constrain cluster masses with sub-percent level precision, comparable to that of Stage IV weak lensing surveys.
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High Energy Astrophysical Phenomena · Cross-listed from nucl-ex

$\beta$-decay Measurements Near the $N=40$ Island of Inversion to Quantify Cooling of Accreted Neutron Star Crusts

K. Hermansen, W.-J. Ong, H. Schatz et al. (+18 more)

Understanding the thermal structure of the outer crust of accreting neutron stars is important to interpret astronomical X-ray observations. Ground-state to ground-state $\beta$-decay transitions of neutron-rich nuclei comprising the crust enable Urca neutrino cooling processes that affect this thermal structure. Here we constrain the ground-state to ground-state transition strengths for the decays of $^{57}$Sc, $^{57}$Ti, and $^{59}$Ti based on experimental data. The data were obtained by combining total absorption $\gamma$-spectroscopy data from the SuN detection system with $\beta$-delayed neutron emission data from the NERO detection system at Michigan State University's National Superconducting Cyclotron Laboratory. We find $\log ft=$5.8$^{+0.3}_{-0.2}$ and $\log ft=$5.34$^{+0.08}_{-0.24}$ for the decays of $^{57}$Ti and $^{59}$Ti, respectively, and find no evidence for ground-state feeding in the decay of $^{57}$Sc. The results indicate weaker transitions than predicted by theory and indicated by previous measurements, resulting in reduced efficiency of neutrino cooling in accreted neutron star crusts in systems that exhibit X-ray superbursts.
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All authors K. Hermansen, W.-J. Ong, H. Schatz, J. Browne, A. Chester, K. Childers, R. Jain, S. Liddick, S. Lyons, S. A. Miskovich, P. Möller, F. Montes, J. Owens-Fryar, A. Palmisano-Kyle, A. L. Richard, N. Rijal, M. Smith, D. Soltesz, A. Spyrou, S. K. Subedi, L. Wagner

Astrophysics of Galaxies

The Two Component Circumgalactic Medium Emission around z~2 Radio-loud Quasars

Sanchit Sabhlok, Shelley A. Wright, Andrey Vayner et al. (+7 more)

We present Ly$\alpha$, He II and C IV observations of 7 redshift ~ 2 radio-loud quasars observed using the Keck Cosmic Web Imager (KCWI) and compare it to observed radio jet emission using archival VLA and ALMA radio observations. We detect 80-120 kpc diameter Ly$\alpha$ and 10-40 kpc He II and C IV emission around the targets. We find the Ly$\alpha$ emission to be brighter in the inner 30 kpc by factors of 2-10 compared to other literature samples. We reproduce the trend for increased total luminosity for a larger area on sky, but find our targets tend to be brighter for a given area when compared to literature observations, even when adjusting for the observational sensitivity. We infer that the He II and C IV is likely powered by quasar photoionization, with the ionizing radiation likely escaping along the radio jet axis which is aligned with the He II and C IV emission. The observations agree with a two component model of the CGM where the inner CGM (< 30 kpc) is directly influenced by the host galaxies, whereas the gas motion in the outer CGM (> 30 kpc) is influenced by gas turbulence and the larger environment around the host galaxies.
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All authors Sanchit Sabhlok, Shelley A. Wright, Andrey Vayner, Norman Murray, Lee Armus, Maren Cosens, James Wiley, Eileen Meyer, Karthik Reddy, Marie Wingyee Lau