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Physics Astrophysics

astro-ph Watch Astrophysics

Friday 5 December

High Energy Astrophysical Phenomena

Hadronic Emissions from the Microquasar V4641 Sgr, SS433, and its implications in the Diffuse Galactic Emission

Basanti Paul, Abhijit Roy, Jagdish C. Joshi et al. (+1 more)

Microquasars (MQs) are Galactic binary systems, consisting of a star and a compact object, a neutron star or a stellar mass black hole, which accretes matter from its companion star and gives rise to relativistic jets. Recent detection of very-high-energy (VHE; $E \gtrsim 100,\text{GeV}$) and ultra-high-energy (UHE; $E \gtrsim 100,\text{TeV}$) gamma-rays by LHAASO, HAWC and HESS from the MQ V4641 Sgr and SS 433 suggests them as Galactic PeVatrons. In this work, we studied a hadronic origin of the observed TeV-PeV gamma-ray emission from these MQs. We considered the hadronic scenario where the gamma-rays are produced by the interaction of relativistic protons in the MQ jet with the stellar wind. We fitted our model with observed data and constrained physical parameters like the hadronic jet power fraction, the proton spectral index, the maximum proton energy and the jet bulk Lorentz factor. Our best-fit model shows hard proton spectra ($1.84-2.44$) and maximum proton energies between 1 and 5 PeV. We also estimated the all-flavor neutrino fluxes corresponding to the gamma-ray fluxes from the hadronic model and found that V4641 sgr can be detected by next-generation neutrino telescopes like KM3NeT-ARCA and TRIDENT. Furthermore, we modeled a synthetic population of Galactic MQs and estimated their contribution to the diffuse TeV-PeV gamma-ray flux. For the inner Galaxy PSR contribution dominates in the range 10-100 TeV, and above 100 TeV diffused cosmic ray interactions with the molecular clouds is most dominant. We find that a population $\sim 14$ MQs is required to explain the LHAASO data above 100 TeV. For the outer Galaxy, we show that MQs are the dominant class of sources, and we constrain their population $\sim$14. Our findings strongly suggest that MQs are efficient particle accelerators, contributing to Galactic PeVatrons and potential multimessenger sources in our Galaxy.
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All authors Basanti Paul, Abhijit Roy, Jagdish C. Joshi, Debanjan Bose

Cosmology and Nongalactic Astrophysics

Constraints on the normal branch of DGP gravity from SPT galaxy clusters with DES and HST weak-lensing mass calibration and from Planck PR4 CMB anisotropies

S. M. L. Vogt, S. Bocquet, C. T. Davies et al. (+49 more)

We present constraints on the normal branch of the Dvali-Gabadadze-Porrati (nDGP) braneworld gravity model from the abundance of massive galaxy clusters. On scales below the nDGP crossover scale $r_{\rm c}$, the nDGP model features an effective gravity-like fifth force that alters the growth of structure, leading to an enhancement of the halo mass function (HMF) on cluster scales. The enhanced cluster abundance allows for constraints on the nDGP model using cluster samples. We employ the SPT cluster sample, selected through the thermal Sunyaev-Zel`dovich effect (tSZE) with the South Pole Telescope (SPT) and with mass calibration using weak-lensing data from the Dark Energy Survey (DES) and the Hubble Space Telescope (HST). The cluster sample contains 1,005 clusters with redshifts $0.25 < z < 1.78$, which are confirmed with the Multi-Component Matched Filter (MCMF) algorithm using optical and near-infrared data. Weak-lensing data from DES and HST enable a robust mass measurement of the cluster sample. We use DES Year 3 data for 688 clusters with redshifts $z < 0.95$, and HST data for 39 clusters with redshifts $ 0.6 < z <1.7$. We account for the enhancement in the HMF through a semi-analytic correction factor to the standard cosmology HMF derived from the spherical collapse model in the nDGP model. We then further calibrate this model using $N$-body simulations. In addition, for the first time, we analyze the primary cosmic microwave background (CMB) temperature and polarization anisotropy measurements from Planck PR4 within the nDGP model. We obtain a competitive constraint from the joint analysis of the SPT cluster abundance with the Planck PR4 data, and report an upper bound of $1/\sqrt{(H_0r_{\rm c})}< 1.41$ at $95\,\%$ when assuming a cosmology with massive neutrinos.
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All authors S. M. L. Vogt, S. Bocquet, C. T. Davies, J. J. Mohr, F. Schmidt, C.-Z. Ruan, B. Li, C. Hernändez-Aguayo, S. Grandis, L. E. Bleem, M. Klein, M. Aguena, S. Allam, F. Andrade-Oliveira, D. Bacon, D. Brooks, R. Camilleri, A. Carnero Rosell, J. Carretero, M. Costanzi, L. N. da Costa, M. E. da Silva Pereira, J. De Vicente, P. Doel, J. Garcïa-Bellido, P. Giles, D. Gruen, G. Gutierrez, S. R. Hinton, D. L. Hollowood, D. J. James, K. Kuehn, S. Lee, J. L. Marshall, J. Mena-Fernändez, F. Menanteau, R. Miquel, J. Myles, A. A. Plazas Malagön, A. Porredon, J. Prat, C. L. Reichardt, A. K. Romer, E. Sanchez, I. Sevilla-Noarbe, M. Smith, M. Soares-Santos, E. Suchyta, M. E. C. Swanson, C. To, V. Vikram, N. Weaverdyck

Earth and Planetary Astrophysics

Most Rocky Sub-Neptunes are Molten: Mapping the Solidification Shoreline for Gas Dwarf Exoplanets

Robb Calder, Oliver Shorttle, Harrison Nicholls et al. (+2 more)

Sub-Neptunes are the most common type of detected exoplanet, yet their observed masses and radii are degenerate with several interior structures. One possibility is that sub-Neptunes have silicate/iron interiors and H$_2$-dominated atmospheres ($\mu$<3.8 g mol$^{-1}$), i.e., they are 'gas dwarfs'. If gas dwarfs have molten interiors, interactions between their magma oceans and atmospheres will produce distinct observational signatures. These signatures may break the degeneracy in interior structure, while providing insight into their interior processes, history, and population trends. We expect all such planets are born molten, but under what conditions do they remain molten today? We use the coupled interior-climate evolution model, PROTEUS, to estimate the 'solidification shoreline': the instellation flux boundary (as a function of stellar $T_{\rm eff}$) that separates molten gas dwarfs from solidified ones. Our results show that 98% of detected sub-Neptunes occupy a region of parameter space consistent with their having permanent magma oceans, if they are gas dwarfs. While mantle $f{\rm O}_2$ and bulk volatile C/H ratio both influence magma ocean cooling, planets with oxidising mantles and carbon-rich atmospheres are likely to have high mean-molecular weight atmospheres ($\mu$>3.8 g mol$^{-1}$) and are thus outside the scope of this study. Therefore, most detected sub-Neptunes, if they are gas dwarfs, have permanent magma oceans. This result motivates further research into the interactions between molten interiors and overlying atmospheres, and campaigns to identify unambiguous signatures of these interactions.
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All authors Robb Calder, Oliver Shorttle, Harrison Nicholls, Tim Lichtenberg, Claire-Marie Guimond

High Energy Astrophysical Phenomena

SRG/eROSITA-SDSS view on the relation between X-ray and UV emission for quasars

S. A. Prokhorenko, S. Yu. Sazonov, M. R. Gilfanov et al. (+5 more)

Motivated by the idea of using quasars as standardizable candles for cosmology, we examine the relation between X-ray (at 2 keV, $L_{\rm 2keV}$) and ultraviolet (at 2500 Angstrom, $L_{\rm 2500}$) monochromatic luminosities of quasars using a sample of 2414 X-ray sources from the SRG/eROSITA all-sky survey cross-matched with the Sloan Digital Sky Survey data release 16 quasar catalogue (SDSS DR16Q), at redshifts between 0.5 and 2.5. These objects are bright both in X-rays and in the optical, so that the sample is characterized by nearly 100% statistical completeness. We have developed a new method for determining the $L_{\rm 2keV}-L_{\rm 2500}$ relation, which consistently takes into account (i) X-ray and UV flux limited object selection, (ii) X-ray and UV variability of quasars, and (iii) the decreasing space density of quasars with increasing luminosity. Assuming a linear relation between $l_{\rm X}\equiv\log(L_{\rm 2keV}/[{\rm erg\,s^{-1}\,Hz^{-1}}])$ and $l_{\rm UV}\equiv\log(L_{\rm 2500}/[{\rm erg\,s^{-1}\,Hz^{-1}}])$, we find the slope, $\gamma=0.69\pm0.02$ (hereafter all uncertainties are quoted at the 68% confidence level), and normalization, $l_{\rm X}=26.47\pm0.02$ at $l_{\rm UV}=30.5$, of the $L_{\rm 2keV}$ ($L_{\rm 2500}$) dependence. These values are not substantially different from the results of previous studies. A key novel aspect of our work is allowance for intrinsic scatter (which adds to the dispersion induced by quasar variability and flux measurement uncertainties) of the $L_{\rm 2keV}-L_{\rm 2500}$ relation in both variables, i.e. in X-ray and UV luminosity. The intrinsic X-ray scatter ($\sigma^2_{\rm intX}=0.063\pm0.005$) strongly dominates over the UV one ($\sigma^2_{\rm intUV}=0.002^{+0.003}_{-0.002}$). Further studies should seek to explain this behaviour in terms of accretion onto supermassive black holes and orientation of quasars with respect to the observer.
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All authors S. A. Prokhorenko, S. Yu. Sazonov, M. R. Gilfanov, S. A. Balashev, A. V. Meshcheryakov, A. V. Ivanchik, I. F. Bikmaev, R. A. Sunyaev

Astrophysics of Galaxies

Stability of the Milky Way Satellite Galaxy Plane under the Influence of Neighbors

S.V. Pilipenko and N.R. Arakelyan

Trajectories of test particles in a time-varying nonspherical gravitational potential model of our Galaxy are considered. The role of the quadrupole component of the potential, which at distances greater than 50 kpc is associated with the distribution of matter in the Galaxy's neighborhood (mainly with the influence of the galaxy M31), is studied. It is shown that perturbations of the potential created by the environment can significantly change the trajectories of particles at distances greater than 100 kpc from the Galactic center, but the magnitude of this effect depends on the still poorly known trajectory of the galaxy M31. For some variants of this trajectory, structures resembling a "thin plane" of satellite galaxies cannot exist for more than 2-3 billion years.
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Solar and Stellar Astrophysics

Multi-band ALMA Polarization Observations of BHB07-11 Reveal Aligned Dust Grains in Complex Spiral Arm Structures

Austen Fourkas, Leslie W. Looney, Zhe-Yu Daniel Lin et al. (+8 more)

Polarization-mode observations from the Atacama Large Millimeter/submillimeter Array (ALMA) are powerful tools for studying the dust grain populations in circumstellar disks. Many sources exhibit polarization signatures consistent with aligned dust grains, yet the physical origin of this alignment remains uncertain. One such source is BHB07-11, a Class I protobinary object in the Pipe Nebula with complex spiral arm structures in its circumbinary disk. While magnetic fields are often invoked to explain grain alignment in the interstellar medium, the contrasting conditions in circumstellar disk environments demand further investigation into grain alignment mechanisms. To determine BHB07-11's dominant polarization mechanism, we leverage ALMA polarization-mode dust continuum observations in Bands 3 ($\lambda$=3.1 mm), 6 ($\lambda$=1.3 mm), and 7 ($\lambda$=0.87 mm), in combination with high-resolution dust continuum and spectral line observations in Band 6. Observed polarization vectors in each band are consistent with emission from aligned grains and follow the structure of the spiral arms as shown in the high-resolution observations. Given the relationship between the observed polarization vector orientation and the spiral arms, we find that the polarization morphology is most consistent with grains aligned through a relative velocity flow between gas and dust in the spiral arms, as envisioned in the recently developed badminton birdie-like alignment mechanism, rather than alignment with a magnetic field or other known alignment mechanisms.
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All authors Austen Fourkas, Leslie W. Looney, Zhe-Yu Daniel Lin, Martin Radecki, Zhi-Yun Li, John J. Tobin, Ian W. Stephens, Manuel Fernández-López, Haifeng Yang, Woojin Kwon, Rachel Harrison

Earth and Planetary Astrophysics

Exoplanet formation inference using conditional invertible neural networks

Remo Burn, Victor F. Ksoll, Hubert Klahr et al. (+1 more)

The interpretation of the origin of observed exoplanets is usually done only qualitatively due to uncertainties of key parameters in planet formation models. To allow a quantitative methodology which traces back in time to the planet birth locations, we train recently developed conditional invertible neural networks (cINN) on synthetic data from a global planet formation model which tracks growth from dust grains to evolved final giant planets. In addition to deterministic single planet formation runs, we also include gravitationally interacting planets in multiplanetary systems, which include some measure of chaos. For the latter case, we treat them as individual planets or choose the two or three planets most likely to be discovered by telescopes. We find that training on multiplanetary data, each planet treated as individual point, is promising. The single-planet data only covers a small range of planets and does not extrapolate well to planet properties not included in the training data. Extension to planetary systems will require more training data due to the higher dimensionality of the problem.
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All authors Remo Burn, Victor F. Ksoll, Hubert Klahr, Thomas Henning

High Energy Astrophysical Phenomena

The X-ray/UV Connection in NGC 5548: A Rapidly Varying Corona

M. Papoutsis, I. E. Papadakis, C. Panagiotou et al. (+2 more)

Recent intensive monitoring campaigns of active galactic nuclei (AGN) have provided simultaneous X-ray, UV, and optical data of unprecedented quality. The observations reveal a strong correlation between the UV and optical variability, but a weaker correlation between the X-ray and UV bands, challenging the standard X-ray reprocessing scenario. We revisit the X-ray/UV connection in NGC 5548 by fitting archival 2014 HST and Swift/XRT light curves assuming X-ray reverberation from a dynamically evolving X-ray corona. Our results show that, as long as the corona height, photon index and power vary over time, X-ray reverberation can explain the observed UV and optical variability within 2% and 5%, respectively (on average). The evolution of the best-fit parameters suggests that fast changes in coronal geometry and energetics on a time scale of days are required to explain the observed variability.
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All authors M. Papoutsis, I. E. Papadakis, C. Panagiotou, E. Kammoun, M. Dovciak

Earth and Planetary Astrophysics

Radial modes of pressure bumps and dips in astrophysical discs

Armand Leclerc, Guillaume Laibe, Elliot Lynch et al. (+1 more)

This study investigates the signatures of pressure extrema on global oscillations in discs. To this end, we use the framework of wave topology to establish a generalised local dispersion relation that includes pressure gradients. We highlight the influence of a previously unrecognized epicyclic-acoustic frequency and derive an analytical criterion for the existence of a branch of modes transiting between the inertial and the pressure bands. We find that pressure extrema consist of wave guides in which such topological modes propagate. The fundamental mode trapped at a pressure bump can propagate at all frequencies, allowing it to resonate with any temporal forcing, while the mode associated with a pressure gap propagates at a fixed frequency, propagates with arbitrary vertical phase velocity. These specific features make them attractive candidates for future discoseismology.
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All authors Armand Leclerc, Guillaume Laibe, Elliot Lynch, Nicolas Perez

Astrophysics of Galaxies

Stellar Cores Live Long and Prosper in Cuspy Dark Matter Halos

Jenni Häkkinen, Alexander Rawlings, Till Sawala et al. (+1 more)

The existence of cuspy or cored centers of dark matter halos is a crucial discriminant between different dark matter models. It has recently been claimed based on dynamical arguments that perfectly cored stellar systems cannot survive inside cuspy dark matter halos, which would make the observation of stellar cores in ultrafaint dwarf galaxies, where dark matter cores cannot form through baryonic processes, a direct falsification of the cold dark matter paradigm. Here, we use idealized simulations to show explicitly that cored stellar systems like those observed in dwarf galaxies can be stable within cuspy dark matter halos over at least several Hubble times. We also demonstrate that observations of ultrafaint dwarf galaxies cannot distinguish mildly positive, flat, or negative inner density slopes, further precluding the dynamical inference of the gravitational potential from the stellar configuration.
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All authors Jenni Häkkinen, Alexander Rawlings, Till Sawala, Matthew G. Walker

Solar and Stellar Astrophysics

The Ratan Active Region Patches (RARPs) Database: A New Database of Solar Active Region Radio Signatures from the RATAN-600 Telescope

Maxim Korelov, Irina Knyazeva, Evgenii Kurochkin et al. (+2 more)

Solar flares and coronal mass ejections, originating from solar active regions (ARs), are the primary drivers of space weather and can disrupt technological systems. Forecasting efforts heavily rely on photospheric magnetic field data from the Space-weather HMI Active Region Patch (SHARPs) data products. However, the crucial energy release occurs higher in the solar corona. Radio observations from instruments like the RATAN-600 telescope directly probe this region, but their scientific use has been hindered by a lack of standardized and accessible data products. To address this gap, we have developed the Ratan Active Region Patches (RARPs) database, a new public resource of multi-frequency radio spectra for solar ARs. Generated using RATANSunPy software, RARPs provides the first standardized radio counterpart to magnetic field archives. The database contains over 160,000 calibrated AR observations from 2009 to 2025, each including 3-18 GHz spectra and rich metadata. We demonstrate the scientific utility of this database by using machine learning to forecast solar flares. The radio spectra are first compressed into low-dimensional embedded features using an autoencoder, which are then used as predictors in baseline logistic regression classifiers. We compare the predictive power of these embedded RARPs features with that of the 18 SHARPs magnetic field parameters provided in the SHARPs data product headers. Our results show that while SHARPs data provides superior flare discrimination, the radio signatures in RARPs possess clear predictive potential and, for M-class and above flares, yield lower Brier Scores and positive Brier Skill Scores relative to SHARPs, indicating more accurate probabilistic forecasts for these events. This establishes radio data as a valuable and complementary information source.
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All authors Maxim Korelov, Irina Knyazeva, Evgenii Kurochkin, Nikolay Makarenko, Denis Derkach

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

p-Wave Dominant Majorana Dark Matter and Its Self-Interactions in a Gauged $U(1)_{L_\mu - L_\tau}$ Model

Kwei-Chou Yang

We propose a model of $p$-wave dominant Majorana dark matter (DM) featuring a macroscopic mass gap in a gauged $U(1)_{L_\mu - L_\tau}$ extension of the Standard Model. Spontaneous symmetry breaking generates a dominant Majorana mass via a strong Yukawa coupling, splitting the dark fermion into two distinct states. The lighter state ($\chi_-$) is the DM candidate, with an allowed mass of $\sim 10$ GeV to several hundred GeV. Crucially, within the $10 \sim 75$ GeV mass range and a scalar mediator at the tens of MeV scale, this strong coupling dictates the thermal relic abundance and induces significant elastic self-interactions. These self-interactions naturally resolve small-scale structure anomalies, such as the core-cusp problem, while satisfying massive cluster constraints. Furthermore, we place stringent joint constraints on the scalar mass and the Higgs mixing angle $\alpha$ using the latest LZ 2025 direct detection data. The model's gauge boson $Z^\prime$ maintains early-Universe thermal equilibrium and accommodates the muon anomalous magnetic moment $(g-2)_\mu$, remaining consistent with updated cosmological and experimental bounds.
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Solar and Stellar Astrophysics

Polarimetric and spectropolarimetric observations with FoReRo2: Instrument overview and standard star monitoring

Yanko Nikolov, Galin Borisov, Stefano Bagnulo et al. (+3 more)

In this paper, we present a description and characterisation of the 2-Channel Focal Reducer Rozhen (FoReRo2), with an emphasis on its polarimetric and spectropolarimetric observation modes. FoReRo2 is a multimode instrument mounted at the Ritchey-Chretien (RC) focus of the 2-meter Ritchey-Chretien-Coude (RCC) telescope at the Bulgarian National Astronomical Observatory (BNAO) - Rozhen. The primary targets of this instrument include novae, Be/X-ray binaries, symbiotic stars, asteroids, and comets. Standard stars with a high degree of polarisation are an essential part of the polarimetric observations. In our sample, HD 204827 shows short-term variability in the position angle (PA), making it unsuitable for calibration. HD 183143 displays intrinsic polarisation variability, but remains stable in terms of the PA. For the first time, we present a statistical study of the K and lambda_max parameters of Serkowski's law, including the mean value, standard deviation, and distribution. To demonstrate FoReRo2's polarimetric capabilities, we present several examples. The recurrent nova RS Oph shows the variability of Serkowski's K parameter, which is due to dust formation within the first few days after the 2021 outburst. These examples also include the imaging polarimetry of comet C/2019 Y4 (ATLAS) and spectropolarimetric observations of the symbiotic star Z And.
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All authors Yanko Nikolov, Galin Borisov, Stefano Bagnulo, Plamen Nikolov, Rumen Bogdanovski, Tanyu Bonev

High Energy Astrophysical Phenomena

CTAO LST-1 observations of magnetar SGR 1935+2154: Deep limits on sub-second bursts and persistent tera-electronvolt emission

K. Abe, S. Abe, A. Abhishek et al. (+333 more)

The Galactic magnetar SGR 1935+2154 has exhibited prolific high-energy (HE) bursting activity in recent years. Investigating its potential tera-electronvolt counterpart could provide insights into the underlying mechanisms of magnetar emission and very high-energy (VHE) processes in extreme astrophysical environments. We aim to search for a possible tera-electronvolt counterpart to both its persistent and sub-second-scale burst emission. We analysed over 25 h of observations from the Large-Sized Telescope prototype (LST-1) of the Cherenkov Telescope Array Observatory (CTAO) during periods of HE activity from SGR 1935+2154 in 2021 and 2022 to search for persistent emission. For bursting emission, we selected and analysed nine 0.1 s time windows centred around known short X-ray bursts, targeting potential sub-second-scale tera-electronvolt counterparts in a low-photon-statistics regime. While no persistent or bursting emission was detected in our search, we establish upper limits for the tera-electronvolt emission of a short magnetar burst simultaneous to its soft gamma-ray flux. Specifically, for the brightest burst in our sample, the ratio between tera-electronvolt and X-ray flux is less than $10^{-3}$. The non-detection of either persistent or bursting tera-electronvolt emission from SGR 1935+2154 suggests that if such components exist, they may occur under specific conditions not covered by our observations. This aligns with theoretical predictions of VHE components in magnetar-powered fast radio bursts and the detection of MeV - GeV emission in giant magnetar flares. These findings underscore the potential of magnetars, fast radio bursts, and other fast transients as promising candidates for future observations in the low-photon-statistics regime with Imaging Atmospheric Cherenkov Telescopes, particularly with the CTAO.
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All authors K. Abe, S. Abe, A. Abhishek, F. Acero, A. Aguasca-Cabot, I. Agudo, C. Alispach, D. Ambrosino, F. Ambrosino, L. A. Antonelli, C. Aramo, A. Arbet-Engels, C. Arcaro, T.T.H. Arnesen, K. Asano, P. Aubert, A. Baktash, M. Balbo, A. Bamba, A. Baquero Larriva, U. Barres de Almeida, J. A. Barrio, L. Barrios Jiménez, I. Batkovic, J. Baxter, J. Becerra González, E. Bernardini, J. Bernete, A. Berti, I. Bezshyiko, C. Bigongiari, E. Bissaldi, O. Blanch, G. Bonnoli, P. Bordas, G. Borkowski, G. Brunelli, A. Bulgarelli, M. Bunse, I. Burelli, L. Burmistrov, M. Cardillo, S. Caroff, A. Carosi, R. Carraro, M. S. Carrasco, F. Cassol, N. Castrejón, D. Cerasole, G. Ceribella, A. Cerviño Cortínez, Y. Chai, K. Cheng, A. Chiavassa, M. Chikawa, G. Chon, L. Chytka, G. M. Cicciari, A. Cifuentes, J. L. Contreras, J. Cortina, H. Costantini, M. Dalchenko, P. Da Vela, F. Dazzi, A. De Angelis, M. de Bony de Lavergne, R. Del Burgo, C. Delgado, J. Delgado Mengual, M. Dellaiera, D. della Volpe, B. De Lotto, L. Del Peral, R. de Menezes, G. De Palma, C. Díaz, A. Di Piano, F. Di Pierro, R. Di Tria, L. Di Venere, R. M. Dominik, D. Dominis Prester, A. Donini, D. Dorner, M. Doro, L. Eisenberger, D. Elsässer, G. Emery, J. Escudero, V. Fallah Ramazani, F. Ferrarotto, A. Fiasson, L. Foffano, F. Frías García-Lago, S. Fröse, Y. Fukazawa, S. Gallozzi, R. Garcia López, S. Garcia Soto, C. Gasbarra, D. Gasparrini, D. Geyer, J. Giesbrecht Paiva, N. Giglietto, F. Giordano, N. Godinovic, T. Gradetzke, R. Grau, D. Green, J. Green, S. Gunji, P. G"unther, J. Hackfeld, D. Hadasch, A. Hahn, M. Hashizume, T. Hassan, K. Hayashi, L. Heckmann, M. Heller, J. Herrera Llorente, K. Hirotani, D. Hoffmann, D. Horns, J. Houles, M. Hrabovsky, D. Hrupec, D. Hui, M. Iarlori, R. Imazawa, T. Inada, Y. Inome, S. Inoue, K. Ioka, M. Iori, T. Itokawa, A. Iuliano, J. Jahanvi, I. Jimenez Martinez, J. Jimenez Quiles, I. Jorge Rodrigo, J. Jurysek, M. Kagaya, O. Kalashev, V. Karas, H. Katagiri, D. Kerszberg, T. Kiyomot, Y. Kobayashi, K. Kohri, A. Kong, P. Kornecki, H. Kubo, J. Kushida, B. Lacave, M. Lainez, G. Lamanna, A. Lamastra, L. Lemoigne, M. Linhoff, S. Lombardi, F. Longo, R. López-Coto, M. López-Moya, A. López-Oramas, S. Loporchio, A. Lorini, J. Lozano Bahilo, F. Lucarelli, H. Luciani, P. L. Luque-Escamilla, P. Majumdar, M. Makariev, M. Mallamaci, D. Mandat, M. Manganaro, D. K. Maniadakis, G. Manicò, K. Mannheim, S. Marchesi, F. Marini, M. Mariotti, P. Marquez, G. Marsella, J. Martí, O. Martinez, G. Martínez, M. Martínez, A. Mas-Aguilar, M. Massa, G. Maurin, D. Mazin, J. Méndez-Gallego, S. Menon, E. Mestre Guillen, S. Micanovic, D. Miceli, T. Miener, J. M. Miranda, R. Mirzoyan, M. Mizote, T. Mizuno, M. Molero Gonzalez, E. Molina, T. Montaruli, A. Moralejo, D. Morcuende, A. Moreno Ramos, A. Morselli, V. Moya, H. Muraishi, S. Nagataki, T. Nakamori, A. Neronov, D. Nieto Castaño, M. Nievas Rosillo, L. Nikolic, K. Nishijima, K. Noda, D. Nosek, V. Novotny, S. Nozaki, M. Ohishi, Y. Ohtani, T. Oka, A. Okumura, R. Orito, L. Orsini, J. Otero-Santos, P. Ottanelli, M. Palatiello, G. Panebianco, D. Paneque, F. R. Pantaleo, R. Paoletti, J. M. Paredes, M. Pech, M. Pecimotika, M. Peresano, F. Pfeifle, E. Pietropaolo, M. Pihet, G. Pirola, C. Plard, F. Podobnik, M. Polo, E. Prandini, M. Prouza, S. Rainò, R. Rando, W. Rhode, M. Ribó, V. Rizi, G. Rodriguez Fernandez, M. D. Rodríguez Frías, P. Romano, A. Roy, A. Ruina, E. Ruiz-Velasco, T. Saito, S. Sakurai, D. A. Sanchez, H. Sano, T. Šarić, Y. Sato, F. G. Saturni, V. Savchenko, F. Schiavone, B. Schleicher, F. Schmuckermaier, J. L. Schubert, F. Schussler, T. Schweizer, M. Seglar Arroyo, T. Siegert, G. Silvestri, A. Simongini, J. Sitarek, V. Sliusar, A. Stamerra, J. Strišković, M. Strzys, Y. Suda, A. Sunny, H. Tajima, M. Takahashi, J. Takata, R. Takeishi, P. H. T. Tam, S. J. Tanaka, D. Tateishi, T. Tavernier, P. Temnikov, Y. Terada, K. Terauchi, T. Terzic, M. Teshima, M. Tluczykont, F. Tokanai, T. Tomura, D. F. Torres, F. Tramonti, P. Travnicek, G. Tripodo, A. Tutone, M. Vacula, J. van Scherpenberg, M. Vázquez Acosta, S. Ventura, S. Vercellone, G. Verna, I. Viale, A. Vigliano, C. F. Vigorito, E. Visentin, V. Vitale, V. Voitsekhovskyi, G. Voutsinas, I. Vovk, T. Vuillaume, R. Walter, L. Wan, M. Will, J. Wójtowicz, T. Yamamoto, R. Yamazaki, Y. Yao, P. K. H. Yeung, T. Yoshida, T. Yoshikoshi, W. Zhang, S. Mereghetti, N. Parmiggiani, C. Vignali, R. Zanin

Astrophysics of Galaxies

First Statistical Detection of MgII-traced Cool Gas Outflows with JWST Towards Cosmic Dawn

Cheqiu Lyu, Haoran Yu, Enci Wang et al. (+9 more)

Galactic-scale outflows are a crucial component of galaxy evolution, yet their properties in the early universe remain poorly constrained. We present the first statistical investigation of \ion{Mg}{2}-traced cool gas outflows in galaxies spanning a wide cosmic timeline from $z \approx 1$ to $z > 6$ (with sample coverage extending to $z \sim 10$). Using thousands of public JWST/NIRSpec spectra, we employ a signal-to-noise weighted spectral stacking technique on the \ion{Mg}{2} $\lambda\lambda2796, 2803$ absorption doublet. We robustly detect blueshifted \ion{Mg}{2} absorption in nearly all stellar mass and redshift bins, with the exception of the lowest-mass systems at $z \sim 1-2$. The outflow equivalent width exhibits a positive correlation with stellar mass ($M_*$) at all epochs, with the fitted slope of $1.21 \pm 0.35$. Our work provides the first statistical constraints on \ion{Mg}{2}-traced cool outflows in the low-mass ($M_* \lesssim 10^{9.5} \, \mathrm{M}_\odot$), high-redshift ($z > 3$) regime. We also find that the outflow velocities generally remain below the host halo escape velocities, consistent with a galactic fountain scenario. The consistency of the stellar mass-outflow equivalent width relation across $z \sim 2-6$ suggests a persistent, unevolving feedback mechanism governing the baryon cycle towards cosmic dawn.
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All authors Cheqiu Lyu, Haoran Yu, Enci Wang, Junxian Wang, Cheng Jia, Jie Song, Yangyao Chen, Jinyang Wang, Zeyu Chen, Chengyu Ma, Yifan Wang, Xu Kong

Instrumentation and Methods for Astrophysics

Commissioning an Inexpensive Off-the-shelf Spectrograph for Radial-Velocity Studies

Lukas Stock and Andreas Schrimpf

We present a way to set up an inexpensive out of the shelf spectrograph at a local observatory. Stability and resolution of the spectrograph are high enough for radial velocity determination of binary stars or determination of stellar characteristics. Even some exoplanets might be detectable via the radial velocity method.
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Cosmology and Nongalactic Astrophysics

Squared-field cross-correlation between kinetic Sunyaev-Zel'dovich effect and 21-cm intensity mapping

Zi-Yan Yuwen, Yu-Er Jiang, Yin-Zhe Ma et al. (+3 more)

Neutral hydrogen (HI) 21-cm intensity mapping is an effective method to track the distribution of baryonic matter, and extract astrophysical and cosmological information. The 21-cm intensity field has a nonvanishing cross-correlation with the kinetic Sunyaev-Zel'dovich (kSZ) effect that traces the velocity and density perturbations of free electrons. By using the linear perturbation theory, in this paper we calculate analytically, for the first time, the cross-correlation between the squared kSZ field and the projection of the squared HI intensity mapping field with the flat-sky approximation. This statistic remains nonvanishing even after the long-wavelength line-of-sight modes ($k_{\parallel}$) are removed due to foreground contamination. We further forecast for the prospects of detection with the SKA-MID 21-cm intensity mapping experiments (redshifts in range of $0.3 < z < 1$), and the kSZ maps measured by the Atacama Cosmology Telescope (ACT) and Simons Observatory (SO). The predicted cumulative signal-to-noise ratio is $1.92$ for SKA-ACT and $3.99$ for SKA-SO. These results show a possible on-the-edge detection on the cross-correlation signal at low redshifts, which in turn could serve as a validation step toward using it for the Epoch of Reionization studies.
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All authors Zi-Yan Yuwen, Yu-Er Jiang, Yin-Zhe Ma, Paul La Plante, Adam Lidz, Yan Gong

Astrophysics of Galaxies

Stellar feedback drives the baryon deficiency in low-mass galaxies

Haoran Yu, Enci Wang, Zeyu Chen et al. (+8 more)

Stellar feedback, as a key process regulating the baryon cycle, is thought to greatly redistribute baryonic material inside and outside the dark matter halos (DMHs), however the observational evidences are lacking. Through stacking analyses of ~400,000 galaxy spectra from Dark Energy Spectroscopic Instrument (DESI), we find star formation driven cool outflows in Mg II absorption line. Assuming only gravity acts on the launched gas, our calculations reveal that outflows from low mass galaxies ($M_*<10^{10}\,\rm M_\odot$) are capable of escaping beyond the DMHs, which aligns well with our finding in the circumgalactic medium (CGM) absorption along the minor-axes of galaxies using background quasars. This research offers indirect evidence that stellar feedback drives the low baryon retention rate in low-mass haloes, implicating that baryonic processes within galaxies are connected with the diffuse matter beyond the DMHs.
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All authors Haoran Yu, Enci Wang, Zeyu Chen, Céline Péroux, Hu Zou, Zhicheng He, Huiyuan Wang, Cheqiu Lyu, Cheng Jia, Chengyu Ma, Xu Kong

Cosmology and Nongalactic Astrophysics

Growth rate measurements from a joint analysis of the large-scale galaxy clustering in Fourier and configuration space

Vincenzo Aronica, Julian E. Bautista, Arnaud de Mattia et al. (+1 more)

In this work, we test a framework to perform the analysis of redshift-space distortions simultaneously in configuration and Fourier space. We test our methods with the AbacusSummit suite of N-body simulations as well as a more numerous set of approximate EZmocks, reproducing the sample of luminous red galaxies of from the Baryon Oscillation Spectroscopic Survey (BOSS) and its extension (eBOSS). Our clustering models are based on the effective field theory of large-scale structures in a Lagrangian frame, used in the latest results from the Dark Energy Spectroscopic Instrument. We perform a template type of analysis, including dilation parameters and the slope parameter from the ShapeFit framework. We find that the joint space inference yields unbiased and robust constraints on simulated datasets, consistent with results from individual spaces or previous methods to obtain consensus results. Our joint space analysis on the the BOSS+eBOSS LRG sample obtains $ f\sigma_8 = 0.463 \pm 0.052 $, in good agreement with the official 2020 results.
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All authors Vincenzo Aronica, Julian E. Bautista, Arnaud de Mattia, Hector Gil-Marín

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

Machine and Deep Learning Regression for Compact Object Equations of State

I. Stergakis, Th. Diakonidis and Ch.C. Moustakidis

A central open problem in nuclear physics is the determination of a physically robust equation of state (EoS) for dense nuclear matter, which directly informs our understanding of the internal composition and macroscopic properties of compact objects such as neutron stars and quark stars. Traditional efforts have relied primarily on theoretical modeling grounded in nuclear and particle physics, with subsequent validation against empirical constraints from heavy ion collisions and, increasingly, multimessenger astrophysical observations. Recent developments, however, have introduced complementary analytical strategies that merge theoretical modeling with advanced data driven methodologies. In particular, Bayesian inference, machine learning, and deep learning have emerged as powerful tools for constraining the EoS and extracting physical insight from complex observational datasets. In this work, we employ state of the art machine learning and deep learning techniques to analyze mass radius relations of compact objects with the aim of reconstructing or inferring their underlying equations of state. The analysis is based on an extensive library of physically consistent, multimodal EoSs for neutron stars and a corresponding set for quark stars, each constructed to satisfy established theoretical and observational constraints. By leveraging the predictive capacity of these computational frameworks, we demonstrate the potential of data-driven approaches to provide refined insights into the behavior of matter at supranuclear densities and to contribute to a more unified understanding of the dense matter EoS.
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Cosmology and Nongalactic Astrophysics · Cross-listed from hep-ph

Gauge-Invariant Bubble Nucleation and Gravitational Waves from First-Order Electroweak Phase Transitions

Jie Liu, Renhui Qin and Ligong Bian

A long-standing problem in electroweak phase transition studies is the spurious gauge dependence of bubble nucleation rate calculations, which introduces large systematic uncertainties in predictions of gravitational waves and related cosmological phenomena. We address this issue by presenting a systematic study of gauge-invariant bubble nucleation within a phenomenologically realistic effective field theory framework. Using the three-dimensional thermal effective field theory formalism with a consistent power-counting scheme, we rigorously establish the gauge invariance of the physical nucleation rate up to two-loop order. This proof eliminates the gauge-parameter dependence of key phase transition parameters, providing a robust theoretical foundation for precise calculations of gravitational waves, electroweak baryogenesis, and primordial magnetogenesis.
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Cosmology and Nongalactic Astrophysics

How Dark Sector Equations of State Govern Interaction Signatures

Peng-Ju Wu, Ming Zhang and Shang-Jie Jin

Using late-Universe observations, we demonstrate that freeing dark energy and dark matter equations of state (EoS) dramatically alters the inferred strength and direction of their interactions. When dark sector EoS are fixed to $w_{\mathrm{de}}=-1$ and $w_{\mathrm{dm}}=0$, the data consistently favor an energy transfer from dark energy to dark matter across various interaction forms. This apparent evidence, however, proves highly sensitive to the EoS assumptions: treating $w_{\mathrm{de}}$ as a free parameter substantially weakens the evidence for interaction, with its value converging to the quintessence regime ($w_{\mathrm{de}}>-1$). In contrast, freeing $w_{\mathrm{dm}}$ maintains a preference for interaction, revealing a correlation where positive $w_{\mathrm{dm}}$ is associated with energy transfer from dark energy to dark matter, and negative $w_{\mathrm{dm}}$ with energy transfer from dark matter to dark energy. These findings caution against the simplistic assumption of $\Lambda$CDM EoS values when attempting to detect a possible interaction. Despite these fundamental degeneracies, model comparison indicates that interacting dark energy scenarios are positively to strongly supported by AIC and DIC, but only inconclusively to weakly supported by Bayesian evidence against the $\Lambda$CDM model.
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High Energy Astrophysical Phenomena

Evolution of the Inner Accretion Flow in Swift J1727.8$-$1613 across Intermediate States: Insights from Broadband Spectral and Timing Analysis

Swadesh Chand, Andrzej A. Zdziarski, Gulab C. Dewangan et al. (+1 more)

We present a comprehensive broadband spectral and variability study of the newly detected black hole X-ray binary Swift~J1727.8–1613 in the intermediate states during its 2023 outburst, using multi-mission observations from NICER, NuSTAR, AstroSat, and Insight-HXMT. Spectral data up to 78 keV in the hard-intermediate state (HIMS) require models with two Comptonizing regions. In contrast, models with a single Comptonizing region adequately describe the soft-intermediate states (SIMS), implying a significant evolution in the disk-corona geometry between the states. The hard X-ray tail above $100$ keV in the HIMS, detected with both AstroSat/CZTI and Insight-HXMT/HE, indicates that the electron population in the corona is not purely thermal but rather hybrid, with a power-law distribution above the thermal cutoff. While both the reflection modeling and disk continuum fitting favor a truncated disk geometry in the HIMS, the disk in the SIMS moves substantially closer to the innermost stable circular orbit, accompanied by a significant rise in disk temperature. This interpretation is further supported by the increase in the QPO frequency from $\sim1.3$ to $\sim6.6$ Hz. From joint modeling of the disk continuum and reflection component and assuming the distance of 3.4 kpc, we estimate a black hole mass of $10.3^{+5.5}_{-2.5}~M_\odot$, spin of $0.79^{+0.07}_{-0.15}$, and the disk inclination angle of $\sim37\degr$–$53\degr$, which match well with the previously reported spectro-polarimetric measurements. We find a weakly variable or stable disk and a highly variable Comptonized component.
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All authors Swadesh Chand, Andrzej A. Zdziarski, Gulab C. Dewangan, Pragati Sahu

Astrophysics of Galaxies

Is Crater II disrupting?

A. Katherina Vivas, Alistair Walker, Clara Martínez-Vázquez et al. (+5 more)

Crater~II (CraII) is a very intriguing, low-surface brightness and extended galaxy in the vicinity of our Milky Way. Motivated by its huge area and the number of RR Lyrae stars (RRLS) detected near to its core, we performed a follow-up campaign to get deep multi-band ($g,i$) and multi-epoch DECam observations in the outskirts of CraII, covering up to 8$r_h$ in the North-East direction and up to 13$r_h$ in the South-West direction (spanning almost 10 degr in the sky across the galaxy). We confirm the existence of tails coming out from CraII. In our survey, we detected a total of 97 periodic variable stars, of which 46 are CraII members [37 RRLS and 7 anomalous Cepheids (AC)]. The RRLS show a strong gradient in distance of 3.7~kpc/deg, which follows the relation: $d (\rm {kpc}) = (-3.70\pm 0.21)\, \xi' + (116.2 \pm 0.32)$ (where $\xi'$ is the planar coordinate rotated to fit the CraII tails). We also found an indication that the gradient in distance in the distant part of the near-side tail (North-East) may be less steep than it is in the inner $5\deg$. The leading tail also displays a significant over-density of RRLS located $\sim 3.25$ deg from the center of CraII. Despite covering a smaller area than previous works, our deeper photometry has allowed us to unveil more variable stars in the region and better define the tidal tails of CraII.
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All authors A. Katherina Vivas, Alistair Walker, Clara Martínez-Vázquez, MJ Cooke, Carme Gallart, Matteo Monelli, Jaime A. Rojas Cancino, David Nidever

Cosmology and Nongalactic Astrophysics

Absorption in the 21 cm Hydrogen Line at $z>10$ as a Sensitive Tool for the Construction of a Cosmological Model on Small Scales

Yu.N. Eroshenko, V.N. Lukash, E.V. Mikheeva et al. (+2 more)

The cosmic microwave background absorption intensity in the 21 cm line of neutral hydrogen in the presence of additional power in the form of a "bump" in the spectrum of cosmological density perturbations is calculated. The main absorption-amplifying effect is the earlier birth of the first stars forming an ultraviolet radiation background. This radiation reduces the spin temperature of neutral hydrogen and, thus, amplifies the absorption in the 21 cm line. A comparison of various cosmological models (with and without a bump in the density perturbation spectrum) shows that it is possible to determine the probable position of the bump in the perturbation spectrum and, thus, to reconstruct the spectrum of cosmological perturbations on scales $k>1$~Mpc${}^{-1}$ from the position of the absorption frequency profile.
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All authors Yu.N. Eroshenko, V.N. Lukash, E.V. Mikheeva, S.V. Pilipenko, M.V. Tkachev

High Energy Astrophysical Phenomena

Search for UHE gamma photons in cosmic rays by studying the geomagnetic influence on air-shower muons

Animesh Basak, Meghamani Haldar, Kishor Chaudhury et al. (+1 more)

A major challenge in ground-based ultra-high-energy gamma-ray observations remains in discriminating sporadic gamma-ray signals from a huge background of cosmic-ray events. To achieve good discrimination power of gamma rays against protons, an unconventional approach is presented that exploits the geomagnetic influence on air shower muons in Monte Carlo shower events. A recognizable polar asymmetry in the positive and negative muon distributions is noticed after transforming the impact coordinates of each muon from the observer plane onto the shower front plane, plus a judicious ignoring of the minimal attenuation of muons in the space between the two planes. A couple of observables, $d_{\text{max}}$ and $N_{\mu; \text{IQS}}^{\text{tr.}}$, can be extracted from the formation of two densely populated positive and negative muon zones in each shower. Both observables demonstrate excellent gamma/proton discrimination power, with efficiencies of $93.2\%$ and $98.6\%$. This analysis permitted the usage of muon detectors just covering a small area of $\simeq{1.4}\%$ of a square-km array for ultra-high-energy gamma-ray observations. It is expected that the present and future gamma-ray observatories will implement the current approach.
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All authors Animesh Basak, Meghamani Haldar, Kishor Chaudhury, Rajat K. Dey

Astrophysics of Galaxies

Investigating Unusually Extended Main Sequence Turnoff of the Galactic Open Cluster NGC 3532

Khushboo K Rao and Wen-Ping Chen

Extended main-sequence turnoffs are observed in the color-magnitude diagrams of some young and intermediate-age star clusters. Here we report the case study of NGC 3532. Among the cluster member candidates identified using the ML-MOC algorithm on Gaia DR3 sources, we found that fast rotators are significantly redder. Stars near the main-sequence turnoff exhibit a multi-modal distribution in the Gaia broadening velocity ($v_{\rm broad}$). A comparison with relevant literature suggests binaries being typically interspersed with fast rotators, often manifesting as slow to moderate rotators. Additionally, chemically peculiar stars are predominantly located in the bluer regions of the turnoff, with those in the fast-rotator region having large values of Gaia re-normalised unit weight error, indicating plausible companions. Our analysis suggests multiple channels responsible for angular momentum loss to account for the extended turnoff.
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High Energy Astrophysical Phenomena

A Persistently Active Fast Radio Burst source Embedded in an Expanding Supernova Remnant

Chen-Hui Niu, Di Li, Yuan-Pei Yang et al. (+21 more)

Fast radio bursts (FRBs) remain one of the most puzzling astrophysical phenomena. While most FRBs are detected only once or sporadically, we present the identification of FRB 20190520B as the first persistently active source over a continuous span of ~ four years. This rare long-term activity enabled a detailed investigation of its dispersion measure (DM) evolution. We also report that FRB 20190520B exhibits a substantial decrease in DM at a global rate of minus 12.4 plus or minus 0.3 pc cm^-3 yr^-1, exceeding previous FRB DM variation measurements by a factor of three and surpassing those observed in pulsars by orders of magnitude. The magnitude and consistency of the DM evolution, along with a high host DM contribution, strongly indicate that the source resides in a dense, expanding ionized medium, likely a young supernova remnant (SNR).
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All authors Chen-Hui Niu, Di Li, Yuan-Pei Yang, Yuhao Zhu, Yongkun Zhang, Jia-heng Zhang, Zexin Du, Jumei Yao, Xiaoping Zheng, Pei Wang, Yi Feng, Bing Zhang, Weiwei Zhu, Wenfei Yu, Ji-an Jiang, Shi Dai, Chao-Wei Tsai, A. M. Chen, Yijun Hou, Jiarui Niu, Weiyang Wang, Chenchen Miao, Xinming Li, Junshuo Zhang

Cosmology and Nongalactic Astrophysics

Spinning Primordial Black Holes and Scalar Induced Gravitational Waves from Single Field Inflation

Abolhassan Mohammadi, Yogesh, Qiang Wu et al. (+1 more)

We investigate the formation of primordial black holes (PBHs), their spin and abundance, in a single-field inflationary model based on a mutated hilltop potential inserted with a small step-like feature. This step induces a brief phase of ultra-slow-roll inflation, producing the large enhancement of the scalar power spectrum required for an appreciable amount of PBH abundance. Instead of the commonly used analytical power spectra, we compute the primordial power spectrum accurately by numerically solving the Mukhanov-Sasaki equation. Using the obtained power spectrum, we apply peak theory with $\nabla^2 \zeta$ treated as a Gaussian random field and parametrize the curvature profile by its amplitude $\mu$ and characteristic width $K$. Confining the study to Type-I PBH, the threshold value is calculated using two robust methods: the average of the compaction function and the q-function method. Using the result, the dimensionless spin parameter of the resulting PBHs is calculated at linear order and found to be $\sqrt{\langle a_\star^2 \rangle} \sim 10^{-3}$; however, it can be higher for smaller masses. We present detailed predictions for two representative parameter sets, calculate the present-day PBH mass function $f_{\rm PBH}(M)$ and the associated scalar-induced gravitational waves (SIGW). The first produces PBHs of mass $M \simeq 10^{-13}\,M_\odot$ that can account for $100\%$ of dark matter, while the second yields $M \simeq 10^{-2}\,M_\odot$ PBHs contributing approximately $2.4\%$ of the dark matter density. The predicted signals of SIGWs lie within the sensitivity bands of future experiments such as LISA, DECIGO, BBO, and SKA. In particular, the second parameter set produces a SIGWs compatible with the recent NANOGrav evidence for a low-frequency gravitational-wave signal.
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All authors Abolhassan Mohammadi, Yogesh, Qiang Wu, Tao Zhu

Instrumentation and Methods for Astrophysics

Ruminations Upon the Modeling of X-ray Foregrounds, Backgrounds and Faint Sources

Adam B. Mantz, Anthony M. Flores, Taweewat Somboonpanyakul et al. (+4 more)

With the goal of extracting as much information as possible from Chandra and XMM-Newton observations of faint, diffuse sources such as galaxy clusters, as well as those of future X-ray telescopes, we present a strategy for forward modeling all the foreground and background signals present in these data. This work leverages widespread efforts to understand the soft X-ray emission from the Galaxy, as well as the cosmic X-ray background and instrument-specific, particle-induced backgrounds. Statistically, a forward model of the foregrounds and backgrounds is preferable to alternatives because it requires no binning of the data, and allows straightforward marginalization over systematic uncertainties. We apply these methods to several galaxy clusters at intermediate-to-high redshifts, spanning a range of masses and morphologies, using Chandra and/or XMM-Newton data. Our results suggest a modest improvement even for relatively bright clusters at these redshifts, and more substantial advantages in the high-redshift, low-surface-brightness regime. We also discuss and provide a simple correction for a time-dependent miscalibration of the Chandra ACIS detectors identified in archival galaxy cluster data.
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All authors Adam B. Mantz, Anthony M. Flores, Taweewat Somboonpanyakul, Steven W. Allen, R. Glenn Morris, Abigail Y. Pan, Haley R. Stueber