Cosmology and Nongalactic Astrophysics · Cross-listed from hep-ph
Cosmic-ray-electron boosted light dark matter: Implications of LZ 2025 data
Sk Jeesun and Anirban Majumdar
Current multiton detectors put stringent constraints on the GeV-scale
galactic dark matter, pushing the allowed cross section almost toward the
neutrino fog, yet remain mostly insensitive to the light dark matter.
Cosmic rays can upscatter the nonrelativistic
halo dark matter particles, making a subpopulation of them gain sufficient kinetic energy to be discernible in current direct search experiments. In this work, we explore this alternate strategy to probe sub-MeV electrophilic dark matter boosted by
cosmic rays with the latest data of LZ 2025 (WS2024 run). We also incorporate the attenuation effect on the boosted dark matter flux during its propagation through the Earth and perform a full numerical treatment to obtain the resulting event rate. Our result shows LZ 2025 data improve the constraint on the MeV scale dark matter by almost $\sim\mathcal{O}(1)$ compared to the previous XENONnT limit for the energy-independent cross section. Using realistic energy-dependent cross sections, we also analyze such a scenario, where the associated mediator mass plays a crucial role in governing the event rate and hence the expected limits too. With energy-dependent cross sections, our obtained limits also remain stronger than the existing constraints from the XENONnT experiment. Even compared to the limits from
neutrino detectors with much larger target masses, LZ 2025 can place stringent constraints in certain regions of the mediator parameter space, particularly in the light-mediator regime, excluding previously unexplored regions.
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Astrophysics of Galaxies
Dynamics of AGN feedback in the X-ray bright East and Southwest arms of M87, mapped by XRISM
A. Simionescu, C. Kilbourne, H. R. Russell et al. (+24 more)
As the central
galaxy in the nearest cluster, M87 provides the best spatial resolution for disentangling the complex interactions between AGN jets and the surrounding environment. We investigate the velocity structure of the multitemperature X-ray gas in M87, particularly in the eastern and southwestern arms associated with past AGN outbursts, using high-resolution spectroscopy from XRISM/Resolve. We analyze a mosaic of XRISM/Resolve observations covering the core of M87, fitting single- and multi-temperature models to spectra extracted from different regions and energy bands. We assess the line-of-sight velocities and velocity dispersions of the hotter ambient and cooler uplifted gas phases, and evaluate systematic uncertainties related to instrumental gain calibration. The hotter ICM phase, traced by Fe He-$\alpha$ emission, shows velocity dispersions below $\sim100$ km/s, and no significant velocity shifts between the arms and a relaxed offset region, suggesting limited dynamical impact from older AGN lobes. In contrast, the cooler gas phase appears to exhibit larger line of sight velocity gradients up to several hundred km/s as well as a higher velocity dispersion than the ambient hot phase, although these conclusions remain tentative pending improvements in the robustness of the gain calibration at lower energies. The first microcalorimeter-resolved map of gas dynamics in M87 supports the uplift scenario for the X-ray arms, with the cooler gas in the east and southwest seemingly moving in opposite directions along the line of sight. The kinetic energy is a small fraction of the gravitational potential energy associated with the gas uplift, and XRISM further suggests that AGN-driven motions may be short-lived in the hot ambient ICM. These constraints provide important input towards shaping future models of AGN feedback.
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All authors A. Simionescu, C. Kilbourne, H. R. Russell, D. Ito, M. Charbonneau, D. Eckert, M. Loewenstein, J. Martin, H. McCall, B. R. McNamara, K. Nakazawa, A. Ogorzalek, A. Tümer, I. Zhuravleva, N. Dizdar, Y. Ezoe, R. Fujimoto, L. Gu, E. Hodges-Kluck, Y. Ichinohe, S. Kitamoto, M. A. Leutenegger, F. Mernier, E. D. Miller, I. Mitsuishi, K. Sato, A. Szymkowiak
Cosmology and Nongalactic Astrophysics
A more inclusive effective dark fluid equation of state parameter: constraints from SKA and Euclid like surveys
Ziad Sakr
We forecast constraints on an effective dark fluid equation of state parameter $w_{\rm eff}$ that encapsulates modified
gravity theories that modifies both the Universe background expansion as well as its large scale structures growth. This is achieved through relating Friedmann equations' dark fluid pressure and density content, thus $w_{\rm eff}$, to modified
gravity parameterized models by mean of the Newtonian potential equation parameter $\mu_0$, the gravitational slip parameter $\eta_0$ and a
redshift dependent Hubble parameter $H_{0,{\rm bck}}$. We adopt next stage SKA survey specifications, alone or in combination with concurrently expected DR3 Euclid survey release, paying
attention to the modeling and recipe of the implementation of the
galaxy clustering and
lensing probes obtained from the two surveys. We consider two data mock models: one with deviation of the intermediate parameters at the level of 10 % (yielding however $w_{\rm eff}=-1.03$) and another sub-percently close to $\Lambda$CDM. We found that the three parameters deviation from $\Lambda$CDM could only be detected at 1 $\sigma$ from SKA alone, while this improves to $\sim$ 2 $\sigma$ when we combine with Euclid. An improvement of the order of 30% on the bounds is reached after projecting the three parameters into a single $w_{\rm eff}$ parameter. However, this affects both cases and thus it does not change much, though it improves the level of detection with respect to $\Lambda$CDM values. We conclude that synergy from both surveys benefits to tighten our constraints, but also that our highly generalized parameterization, although impacting at both the background and the perturbation level, will be hard to disentangle from $\Lambda$CDM at the level at which our forecast is performed and it still needs, to the least, data from more advanced stages of the adopted surveys to hope reach this target.
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High Energy Astrophysical Phenomena · Cross-listed from nucl-th
Universal relation between dipole polarizability of finite nuclei and neutron-star compactness
P.S. Koliogiannis, T. Ghosh, E. Yuksel et al. (+1 more)
The
nuclear equation of state, which determines the structure and properties of
neutron stars, remains subject to substantial theoretical uncertainties, leading to model dependence in predicted observables. Universal relations have emerged as a powerful tool to mitigate this dependence by linking
neutron star observables in a framework-independent manner. In this work, we introduce a new universal relation that bridges finite
nuclei and
neutron stars through the dimensionless quantity $\zeta = \beta_{1.4}\tilde{L}^{-1}$, which couples the compactness of a $1.4~M_{\odot}$
neutron star to the slope of the
nuclear symmetry energy at saturation. The relation is examined under a broad set of relativistic energy density functionals with point-coupling and
meson-exchange interactions, as well as non-relativistic Skyrme functionals. We demonstrate that $\zeta$ exhibits a strong exponential correlation with the electric dipole polarizability $\alpha_D$ in finite
nuclei across all considered equations of state. By exploiting experimental $\alpha_D$ data for selected
neutron-rich
nuclei, we constrain $\zeta$ and translate these constraints into equation-of-state independent bounds on the
neutron star radius $R_{1.4}$ and the
symmetry-energy slope $L$, providing insights into the properties of
neutron star matter.
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All authors P.S. Koliogiannis, T. Ghosh, E. Yuksel, N. Paar
Astrophysics of Galaxies
Extragalactic Planetary Nebulae (xPNe). Determining Distances out to 100 Mpc and the Renaissance of the PN Luminosity Function Method
Magda Arnaboldi, Ortwin Gerhard, Martin Roth et al. (+9 more)
The discrepancy of the Hubble parameter H0 as measured from the
cosmic microwave background versus that found from traditional distance ladder measurements has produced considerable discussion about the need for another force in cosmology. However the significance of the discrepancy depends on understanding the systematic associated with crowding,
metallicity effects, and extinction of the
stellar tracers. Thus additional precision distance indicators in the local universe are desperately needed for investigating the H0 tension. The analysis of MUSE archival data makes the case that the Planetary Nebula Luminosity Function (PNLF) has become such an indicator, as the method can reach distances comparable to HST distances of Cepheid at a fraction of a cost, in terms of
telescope time and ground-based. With new wide-field spectroscopic facilities it becomes possible to measure distances to early-type
galaxies (ETGs) using the PNLF out to 100 Mpc distance, achieving a precise estimate for the H0 value which is independent of the Type Ia
supernova calibration, with only single-epoch measurements.
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All authors Magda Arnaboldi, Ortwin Gerhard, Martin Roth, Peter M. Weilbacher, Souradeep Bhattacharya, Johanna Hartke, Chiara Spiniello, Azlizan Soemitro, Claudia Pulsoni, Lucas Valenzuela, George Jacoby, Robin Ciardullo
Cosmology and Nongalactic Astrophysics
Cosmography with $\Lambda$-Szekeres Models
Morag Hills and Asta Heinesen
The cosmological tensions present in the $\Lambda$ cold dark matter model that have emerged and strengthened over recent years motivate model independent approaches to analysing data. Cosmography is useful for interpreting data in cosmology without imposing assumptions about the field equations of
gravity or the matter content in the Universe. Some cosmography methods, denoted covariant cosmography, go even further and stay agnostic to the underlying space-time metric. Due to their high level of generality, covariant cosmography methods can incorporate the anisotropies and inhomogeneities in the observer's vicinity, and may in turn inform about the associated
curvature of the relevant structures in our
cosmic neighbourhood. Thus, covariant cosmography is a powerful model-independent tool for analysing cosmological data while also enabling the mapping of our local
cosmic neighbourhood. In order to be able to explore the covariant cosmography framework to its fullest, it must be tested in tractable models and simulations. In this paper we derive the cosmography of luminosity distance to fourth order in
redshift and investigate it in the special case of axially symmetric Szekeres models. We compare the numerical results for the distance-
redshift relations of synthetic observers placed within the Szekeres structures with the predictions from the cosmography, and comment on the found level of approximation of the cosmography in relation to other results in the litterature.
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Earth and Planetary Astrophysics
The Origins of Planets for ArieL (OPAL) Key Science Project: the end-to-end planet formation campaign for the ESA space mission Ariel
Danae Polychroni, Diego Turrini, Romolo Politi et al. (+7 more)
The growing body of atmospheric observations of
exoplanets from space and ground-based facilities showcases how the great diversity of the planetary population is not limited to their physical properties but extends to their compositions. The ESA space mission Ariel will observe and characterise hundreds of exoplanetary atmospheres to explore and understand the roots of this compositional diversity. To lay the foundations for the Ariel mission, the OPAL Key Science Project is tasked with creating an unprecedented library of realistic synthetic atmospheres spanning tens of elements and hundreds of molecules on which the Ariel consortium will test and validate its codes and pipelines ahead of launch. In this work we describe the aims and the pipeline of codes of the OPAL project, as well as the process through which we trace the genetic link connecting
planets to their native protoplanetary disks and host
stars. We present the early results of this complex and unprecedented endeavour and discuss how they highlight the great diversity of outcomes that emerge from the large degeneracy in the parameter space of possible initial conditions to the
planet formation process. This, in turn, illustrates the growing importance of interdisciplinary modelling studies supported by high-performance computing methods and infrastructures to properly investigate this class of high-dimensionality problems.
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All authors Danae Polychroni, Diego Turrini, Romolo Politi, Sergio Fonte, Eugenio Schisano, Elenia Pacetti, Paolo Matteo Simonetti, Michele Zusi, Sergio Molinari, Stavro Ivanovski
Instrumentation and Methods for Astrophysics
The Astrosky Ecosystem: An independent online platform for science communication and social networking
Emily L. Hunt, Vincent S. Carpenter, Kyle W. Cook et al. (+5 more)
While almost everything that astronomers study occurs in the
vacuum of space, astronomy itself does not `happen in a
vacuum'. Interactions between scientists, as well as outreach to members of the public, improve extensively from access to good communication tools. Social media has become a key tool for communication in astronomy, being widely used by individuals and organizations alike for networking, outreach, and more. However, traditional social media is reliant on benevolent corporations providing a free service without compromising on quality, and the recent takeover and decline of Twitter has shown how vulnerable these platforms can be. In this proceeding, we present The Astrosky Ecosystem, which is an initiative to develop open-source tools and integrations for social media, principally the Bluesky social network. We explain how our project enables the astronomy community to operate its own social media infrastructure, independent of for-profit corporations. We also discuss some of the project's technical aspects, including its use of the AT Protocol for social networking, before concluding with ideas for the future.
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All authors Emily L. Hunt, Vincent S. Carpenter, Kyle W. Cook, Douglas G. Hilton, Mehnaaz Asad, Janine Jochum, Kelly Lepo, Jamie Zvirzdin
Astrophysics of Galaxies
Kinematics of young star clusters in the outer north-eastern region of the Small Magellanic Cloud
Andrés E. Piatti
It has been suggested since recent time that the magnitude of the interaction between
galaxies could be measured from the level of kinematic disturbance of their outer regions with respect to the innermost ones. Here, I proved that the outer north-eastern region of the Small Magellanic Cloud (SMC), a relatively recent
stellar structure with a
tidal origin from the interaction with the Large Magellanic Cloud, is imprinted by a residual velocity pattern. I obtained from GEMINI GMOS spectra mean radial velocities of
star clusters formed in situ, which added to derived mean proper motions and heliocentric distances, allowed to compute their 3D space velocity components. These space velocities differentiate from those that the clusters would have if they instead orderly rotated with the
galaxy, i.e., their residual velocities are larger than the upper limit for an object pertaining to the SMC main body rotation disk. The level of kinematic disturbance depends on the SMC rotation disk adopted;
galaxy rotation disks traced using relatively old objects are discouraged.The resulting kinematic disturbance arises in younger and older
stellar populations, so that the epoch of close interaction between both Magellanic Clouds cannot be uncovered on the basis of the kinematics behavior of
stellar populations populating the outer SMC
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Solar and Stellar Astrophysics
Six New Circumbinary Disk Occultation (CBO) Candidates from the Zwicky Transient Facility
Zhecheng Hu, Wei Zhu, Shuming Wang et al. (+1 more)
Circumbinary disk occultation (CBO) systems, in which a misaligned circumbinary disk periodically obscures the central binary, provide unique probes of disk structure and dynamics. However, fewer than ten candidates with measured orbital periods were previously known. In this work, we identify six new CBO candidates, designated ZTF-CBO-1 through ZTF-CBO-6, through a systematic search of Zwicky Transient Facility (ZTF) photometry. These systems exhibit deep ($\gtrsim$1 mag) periodic dimming events with orbital periods ranging from $\sim$30 to $\sim$530 days and occultation durations spanning 32%-77% of their orbital periods. Such large duty cycles rule out the interpretation of circum-companion material occultation. Spectral energy distributions of ZTF-CBO-1 and ZTF-CBO-2 reveal infrared excess indicative of a
dust component. TESS observations of ZTF-CBO-1 show no hours- to days-timescale variability during ingress and egress, indicating a smooth disk edge. These discoveries nearly double the known CBO sample, enabling meaningful population-level studies.
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All authors Zhecheng Hu, Wei Zhu, Shuming Wang, Sharon Xuesong Wang
Solar and Stellar Astrophysics
Gaia20dsk: A new MNor discovered by the GLORIOUS collaboration
Patrik E. Németh, Fernando Cruz-Sáenz de Miera, Ágnes Kóspál et al. (+10 more)
Context. Among known young
stellar objects (YSOs), those exhibiting the most dramatic increases in brightness due to sudden increase in mass
accretion rate are eruptive young
stars.
Gaia20dsk is one of the
Gaia-alerted young
star candidates that has displayed a double, nonperiodic brightening resembling that of other young eruptive
stars. Aims. The goal of this work is to determine the physical and
accretion properties of
Gaia20dsk to confirm its classification as an eruptive young
star. Methods. We combined publicly available optical and near-infrared (NIR) photometry with our X-shooter optical/NIR spectrum. In our analysis, we examined the optical and IR light curves from the bursts, reviewing the color-magnitude diagrams across different bands, reporting the detection of emission lines, and providing estimates of the
star's
accretion rates during the burst. Results. The optical light curve shows two major and one brief brightening events with a maximum amplitude of ~1.8 mag in the last five years. A classification based on spectral index indicates that
Gaia20dsk is a flat-spectrum
star. The X-shooter spectrum exhibit emission lines characteristic of accreting low-to-intermediate-mass young
stars, displaying features typical of MNor-type objects. The mass
accretion rate is between (0.5-1.8)*10^{-6} M_sun/yr. Conclusions.
Gaia20dsk is an eruptive YSO that exhibits photometric features similar to those of MNors, including its characteristic brightening amplitude and burst duration, along with similar spectroscopic features and
accretion rates.
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All authors Patrik E. Németh, Fernando Cruz-Sáenz de Miera, Ágnes Kóspál, Eleonora Fiorellino, Zsófia Nagy, Máté Szilágyi, Michal Siwak, Foteini Lykou, Mária Kun, Péter Ábrahám, Zsófia Marianna Szabó, Teresa Giannini, Lukasz Wyrzykowski
Cosmology and Nongalactic Astrophysics
Flux-ratio anomalies in cusp quasars reveal dark matter beyond CDM
Siyuan Hou, Shucheng Xiang, Yue-Lin Sming Tsai et al. (+7 more)
Strongly lensed
quasars in cusp configurations provide a uniquely sensitive probe of small-scale dark matter structure. Using the largest microlensing-free flux ratios for 17 quadruply imaged cusps, we combine these with extensive Monte Carlo simulations of mock lens realizations under cold dark matter (CDM), self-interacting dark matter (SIDM), and fuzzy dark matter (FDM) scenarios. Building on this, we propose a region (minor-axis and narrow major-axis cusp lenses) where flux-ratio anomalies persist even under globally parameterized models ("macromodels") with multipole freedom (capturing disk, asymmetric, or merger-driven structures). Within this region, J1042+1641 is $>3\sigma$ incompatible with both CDM and SIDM. Our results yield a Bayes factor exceeding $100$, providing very strong evidence for FDM over even the most optimistic CDM and SIDM scenarios. As only 11 cusp lenses lie within this region, extending to larger samples will be essential for assessing its statistical generality and for decisively confirming these findings with future microlensing-free flux ratio data.
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All authors Siyuan Hou, Shucheng Xiang, Yue-Lin Sming Tsai, Daneng Yang, Yiping Shu, Nan Li, Jiang Dong, Zizhao He, Guoliang Li, Yizhong Fan
Astrophysics of Galaxies
Magnetic threads and gravity: ALMA Observations of IRDC G14.225-0.506
Nacho Añez-López, Gemma Busquet, Josep Miquel Girart et al. (+14 more)
During the
star formation process, the interplay between
gravity,
turbulence, and B-fields is significant, with B-fields apparently serving a regulatory function. However, the extent to which B-fields are decisive relative to
turbulence and
gravity remains uncertain. This study aims to ascertain the role of B-fields in the fragmentation of molecular clouds. We examine the B-field observed with ALMA at core scales towards the infrared dark cloud G14.225-0.506, focusing on 3 regions with shared physical conditions, and juxtapose it with prior observations at the Hub-filament system scale. Our findings indicate a similar B-field strength and fragmentation level between the 2 hubs. However, distinct B-field morphologies are identified across the 3 regions where polarized emission is detected. In the region N, the large-scale B-field, which is perpendicular to the filamentary structure, persists at smaller scales in the southern half but becomes distorted near the more massive condensations in the northern half. Notably, these condensations exhibit signs of impending collapse, as evidenced by supercritical mass-to-flux values. In the region S, the B-field is considerably inhomogeneous among the detected condensations, and we do not observe a direct correlation between the field morphology and the condensation density. Lastly, in an isolated
dust clump located within a southern filament of the northern hub, the B-field aligns parallel to the elongated emission, suggesting a transition in the field geometry. The B-field shows a clear
evolution with spatial scales. We propose that the most massive condensations detected in the northern Hub are undergoing gravitational collapse, as revealed by the relative significance of the
magnetic field and gravitational potential and mass-to-flux ratio. The distortion of the B-field could be a response to the flow of material due to the collapse.
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All authors Nacho Añez-López, Gemma Busquet, Josep Miquel Girart, Junhao Liu, Qizhou Zhang, Patrick Koch, Anaëlle Maury, Hauyu Baobab Liu, Zhi-Yun Li, Keping Qiu, Shanghuo Li, Huei-Ru, Vivien Chen, Ya-Wen Tang, Shih-Ping Lai, Ramprasad Rao, Paul Ho
Solar and Stellar Astrophysics
Superhumps in active dwarf novae. Part I: ER Ursae Majoris
K. Bakowska, B. Kirpluk, P. Zielinski et al. (+4 more)
We report photometry results of a frequently outbursting
dwarf nova, ER Ursae Majoris. To measure the outburst parameters of the system, we carried out analyses of the light curve, periodograms, and O-C diagrams. We investigated the system's behaviour using the ground-based optical data and the Transiting
Exoplanet Survey Satellite data. During these observation runs, we scrutinised three superoutbursts and several normal outbursts. We detected ordinary and late superhumps during each of the investigated superoutbursts. We derived the period excess value $\epsilon \approx 3.0(1)\% $. This suggests that over the last 30 years, ER UMa has not shifted on the evolutionary path toward period-bounce objects. Between 1992 and 2022, the interval between two successive superoutbursts (the supercycle length) changed significantly from 42.1 days to 59.6 days, which indicates that the mean mass-transfer rate of ER UMa has been decreasing over this period.
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All authors K. Bakowska, B. Kirpluk, P. Zielinski, M. Motylinski, A. Gurgul, J. Golonka, K. Szyszka
Earth and Planetary Astrophysics
Mercury-Ar$\chi$es: a high-performance n-body code for planet formation studies
Diego Turrini, Sergio Fonte, Romolo Politi et al. (+4 more)
Forming planetary systems are populated by large numbers of gravitationally interacting planetary bodies, spanning from massive
giant planets to small planetesimals akin to present-day asteroids and comets. All these planetary bodies are embedded in the gaseous embrace of their native protoplanetary disks, and their interactions with the disk gas play a central role in shaping their dynamical
evolution and the outcomes of
planet formation. These factors make realistic
planet formation simulations extremely computationally demanding, which in turn means that accurately modeling the formation of planetary systems requires the use of high-performance methods. The
planet formation code Mercury-Ar$\chi$es was developed to address these challenges and, since its first implementation, has been used in multiple exoplanetary and
Solar System studies. Mercury-Ar$\chi$es is a parallel n-body code that builds on the widely used Mercury code and is capable of modeling the growth and migration of forming
planets, the interactions between planetary bodies and the disk gas, as well as the evolving impact flux of planetesimals on forming
planets across the different stages of their formation process. In this work we provide the up-to-date overview of its physical modeling capabilities and the first detailed description of its high-performance implementation based on the OpenMP directive-based parallelism for shared
memory environments, to harness the multi-thread and vectorization features of modern processor architectures.
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All authors Diego Turrini, Sergio Fonte, Romolo Politi, Danae Polychroni, Scigé J. Liu, Paolo Matteo Simonetti, Simona Pirani
High Energy Astrophysical Phenomena
[HP99] 159 – Properties of the first Supersoft X-ray Source with a Helium star donor
Hélène Szegedi, Philip A. Charles, David A. H. Buckley et al. (+3 more)
[HP99] 159 is remarkable as the first supersoft X-ray source (SSS) identified with an evolved helium
star donor. With a likely orbital period of 1.164 d or 2.327 d, the origin of the SSS component is controversial, with the two current models being either steady He-burning on the white
dwarf surface, or that it is a helium nova in the decaying phase. To help resolve this issue we present extensive new long-term spectroscopy (with SALT) and photometry (at SAAO and with OGLE) of [HP99] 159 which (a) supports 2.327 d as the orbital period, and (b) finds only a small He II radial velocity modulation. The latter is surprising as it implies a very low inclination system, whereas our light curve modelling suggests $i{\sim}50^\circ$, and hence that the He II must be produced in outflowing material further above, or beyond, the disc. We find that the decaying nova model cannot fit our OGLE light curve and the observed SSS flux level. [HP99] 159 has been essentially constant as an SSS over several decades, implying a sustained high level of mass-transfer from its He
star donor, making it the only confirmed single-degenerate scenario SN Ia progenitor. We have updated the known SSS binary parameters and find a clear $\sim$1.5 mag difference in their $M_{\rm V}$ when compared to the $M_{\rm V} - \Sigma$ properties of LMXBs, likely due to the larger irradiated areas and more luminous donors.
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All authors Hélène Szegedi, Philip A. Charles, David A. H. Buckley, Pieter J. Meintjes, Przemek Mróz, Andrzej Udalski
Astrophysics of Galaxies
Improved measurements of the age of JWST galaxies at z=6-10
M. Lopez-Corredoira and C. M. Gutierrez
From James Webb Space
Telescope (JWST) surveys, 31
galaxies with average
redshift 7.3 are selected containing large Balmer break, Lyman-$\alpha$ break (V-shaped SED versus $\lambda$). Apart from Hubble Space
Telescope (HST) and JWST-NIRCam (Near-infrared camera) photometry for these
galaxies, there are JWST-NIRSpec (Near-infrared spectrograph) spectra for 13
galaxies and mid-infrared photometry (mostly JWST-MIRI) for 15 of them. Spectroscopical analyses included Balmer emission lines, Balmer + 4000 angstroms breaks or CaII lines. Spectral energy distribution (SED) fitting with photometry include old and young
stellar populations, emission lines associated to HII regions, AGN, interstellar
dust extinction and intergalactic extinction from neutral hydrogen. By adopting realistic extinction curves and taking into account the V-shaped SED and low emission at near infrared at rest, the analyses show that AGN contribution in these
galaxies ('little red dots' most of them) should be small on average in the reddest wavelengths, though important for few of the 31
galaxies. Average age of the 31
galaxies: $0.61\pm 0.31$(95% CL) Gyr, while the average age of the $\Lambda $CDM universe is 0.70 Gyr. This corresponds to a formation epoch $z_{ form.}>11.2$(97.5% CL). Reddest
galaxies present largest ages. One of these very red
galaxies gets an age incompatible to be younger than the age of the Universe within $>4.7\sigma$. TP-AGB effect cannot explain this tension. None the less, there may be other uncertainties in the models, so this tension is a provisional result and further research is needed to confirm it.
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Instrumentation and Methods for Astrophysics
Illuminating the Physics of Cosmic Origin and Evolution: A UK Space Frontiers 2035 White Paper
Florian Beutler, Eva-Maria Mueller, Seshadri Nadathur et al. (+61 more)
Understanding the Universe's origins and
evolution remains one of the most fundamental challenges in modern cosmology. This white paper explores three key science priorities in this field: unravelling the physics of
cosmic inflation, investigating the accelerating expansion of the Universe, and precisely measuring the sum of the
neutrino masses. Achieving these goals requires a dedicated survey to map the large-scale structure at high
redshift in unprecedented detail. We describe how this can be achieved through a mission concept called SIRMOS, providing a high-throughput, highly multiplexed spectroscopic capability to obtain accurate
redshifts for over 100 million
galaxies over a wide sky area. Such a survey would leverage the deepest existing wide-area photometric catalogues for targeting, with spectra offering continuous 1.25-2.5~$\mu$m wavelength coverage at moderate resolution, allowing precise
redshift measurements in the $1<z<4$ range with minimal bias. We outline the scientific opportunities this presents. Recent years have seen significant advances in instrumentation, including digital micromirror devices, complex
telescope mirrors, large detector arrays, and data processing pipelines. While these technologies have been demonstrated in terrestrial applications, such a survey is a unique opportunity to apply these proven capabilities in space to address fundamental questions in cosmology. Participation in such a mission will simultaneously deliver a compelling science case, help align UK Space Agency and STFC strategies, demonstrate the UK's growing capability in end-to-end space missions, and strengthen the national space economy through high-value industrial participation.
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All authors Florian Beutler, Eva-Maria Mueller, Seshadri Nadathur, Yun Wang, David Alonso, Tessa Baker, Sownak Bose, Rebecca Canning, Shaun Cole, Fergus Cullen, Willem Elbers, Pedro Ferreira, Carlos Frenk, Oscar Gonzalez, Or Graur, Boryana Hadzhiyska, Alex Hall, Catherine Heymans, Sergey Koposov, Kazuya Koyama, Ofer Lahav, Baojiu Li, Avery Meiksin, Johannes Noller, John Peacock, Alkistis Pourtsidou, Giorgio Savini, Andy Taylor, Rita Tojeiro, David Wands, Massimo Robberto, Gregory Wirth, Mark Dickinson, Thomas Greene, Jeffrey Kruk, Will Percival, Andreas Faisst, Lynne Hillenbrand, Jeyhan Kartaltepe, Nikhil Padmanabhan, Lado Samushia, Lee Armus, Andrew Benson, Micol Bolzonella, Samuel Brieden, Jarle Brinchmann, Robert Content, Emanuele Daddi, Kyle Finner, Andrew Hearin, Cullan Howlett, Jon Lawrence, Gregory Mosby, Zoran Ninkov, Ken Osato, Casey Papovich, Jack Piotrowski, Lucia Pozzetti, Alvise Raccanelli, Jason Rhodes, Shun Saito, Hee-Jong Seo, Zachary Slepian, Steve Smee
Cosmology and Nongalactic Astrophysics
When Primordial Black Holes Absorb During the Early Universe
Md Riajul Haque, Rajesh Karmakar and Yann Mambrini
We study the
evolution of
primordial black holes (PBHs) formed in the early universe in the presence of a surrounding thermal bath. By incorporating the effects of thermal absorption, we show that PBHs can undergo significant mass growth, leading to extended lifetimes and substantial deviations from the standard Hawking evaporation scenario. We find a critical collapse efficiency, $\gamma_{\rm c} \simeq 0.395$, above which the PBH mass grows without bound. This correction has profound implications for both PBH-induced reheating and dark matter (DM) production. Specifically, we find that the reheating temperature can be suppressed, and the DM parameter space for the PBH reheating scenario can undergo $\mathcal{O}(10)$-$\mathcal{O}(10^4)$ corrections, depending on the PBH formation mass and collapse efficiency. Moreover, our results significantly shift the parameter space in which PBHs can account for the entirety of the DM. To the best of our knowledge, this is the first comprehensive phenomenological study to incorporate thermal absorption into PBH
evolution and quantify its impact on cosmological observables.
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High Energy Astrophysical Phenomena
Pushchino Multibeam Pulsar Search. X. Observations of pulsars at declinations above $+53^o$
S.A. Tyul'bashev, G.E. Tyul'basheva and M.A. Kitaeva
A search for
pulsars was carried out using a Large Phased Array (LPA)
radio telescope at a frequency of 110.4 MHz with a time resolution of 3.072 ms and a frequency resolution of 19.5 kHz with a 2.5 MHz bandwidth used. The survey was conducted in a site with declinations of $+53^\circ < \delta < +87^\circ$. The viewing area is approximately 4100 sq.deg. The search was carried out using
Fourier power spectra. To increase sensitivity, multiple observations were made in each direction in the sky, and the resulting power spectra were summarized. This made it possible to increase sensitivity by about 5-10 times, depending on the direction in the sky. A blind search opened 35 known
pulsars. Estimates of the flux density for 33
pulsars have been obtained.
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Cosmology and Nongalactic Astrophysics
One H2 molecule per ten million H-atoms reveals sub-pc scale cold overdensities at z~4
P. Noterdaeme, S. Balashev, T. Berg et al. (+11 more)
We present the detection and analysis of H2 absorption at z = 4.24 towards the bright
quasar J0007-5705, observed with the Very Large
Telescope as part of the ESPRESSO
QUasar Absorption Line Survey (EQUALS). The high resolving power, R~120000, enables the identification of extremely weak H2 lines in several rotational levels at a total column density of N(H2)~2x10^14 cm^-2, among the lowest ever measured in
quasar absorption systems. Remarkably, this constitutes the highest-
redshift H2 detection to date. Two velocity components are resolved, separated by only 3 km/s: a narrow (b~1.7 km/s) and a broader (b~6.2 km/s) component. Modelling the rotational population of H2 yields density of log nH/cm^-3 ~ 2.8 with temperature of ~40K (typical of the cold neutral medium) for the narrow component and log nH/cm^-3 ~ 1.4 , T~600K for the warmer, more turbulent component under a moderate ultraviolet (UV) field, suggesting at least several Mpc distance from the
quasar. This system reveals the existence of tiny (down to ~0.01 pc), cold overdensities in the neutral medium. Their detection among only 7 damped Lyman-alpha systems in EQUALS suggests that they may be widespread yet usually remain undetected. H2 provides an exceptionally sensitive probe of these structures: even a minute molecular fraction produces measurable Lyman-Werner absorption lines along the extremely narrow optical beam – the size of the
quasar's
accretion disc – when observed at sufficiently high spectral resolution. High-resolution spectroscopy on extremely large
telescopes may routinely detect and resolve such structures in the distant Universe, when 21-cm absorption will trace the collective contribution of many cold cloudlets toward larger
radio background sources.
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All authors P. Noterdaeme, S. Balashev, T. Berg, S. Cristiani, R. Cuellar, G. Cupani, S. Di Stefano, V. D'Odorico, C. Fian, B. Godard, S. López, D. Milaković, A. Trost, L. Welsh
Instrumentation and Methods for Astrophysics
ALMA publication statistics
Felix Stoehr, María Díaz Trigo, Evanthia Hatziminaoglou et al. (+9 more)
The success of an astronomical facility is measured by its scientific impact. A principal metric for this impact is the ensemble of peer-reviewed publications based on the observational data obtained by the facility. We present a comprehensive study of the statistics of the 4190 refereed publications of the Atacama Large Millimeter/Submillimeter Array (ALMA) in the period from 2012 to 2024. The publications have received 169,985 citations and are based on 2670 ALMA projects totalling 19,265 hr of 12 m-array-equivalent observing time. Our study analyses publication statistics related to various aspects, e.g., science categories, geographical distribution, archival research, time to publication, publication fraction, and citations. We also look into the community and compare ALMA with other facilities. We find that ALMA is a high-impact observatory with ~70% of observed projects published, ~40% of publications making use of archival data in 2024, more than 9400 unique authors, and a publication
evolution following that of HST and VLT. Currently, the impact factor for ALMA publications is larger than that of all other major astronomical facilities. ALMA also plays a pivotal role in very long baseline interferometry, substantially contributing to landmark achievements such as capturing the first image of a black hole shadow.
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All authors Felix Stoehr, María Díaz Trigo, Evanthia Hatziminaoglou, Uta Grothkopf, Silvia Meakins, Leslie Kiefer, Lance Utley, Mika Konuma, Eelco van Kampen, Gergö Popping, Enrique Macias, Martin Zwaan
High Energy Astrophysical Phenomena
Constraining Twin-Star Existence in Four-Parameter Maxwell Equation of State
Shamim Haque, Atharva Shinde, Asim Kumar Saha et al. (+2 more)
Twin
stars (TSs) are predicted to exist in nature if the
hadron-to-
quark phase transition is strong enough to form a new branch of hybrid
stars, separated from the branch of
neutron stars. It is essential to study the hybrid equation of states (EoSs) that can form TSs, with a primary focus on estimating the onset of the phase transition and its strength. We systematically study the TS scenario by adopting a four-parameter Maxwell-CSS approach to construct a large ensemble of Maxwell-type hybrid EoSs. Within this framework, we report the conditions on our parameter space imposed by the TOV solutions. For a fixed transition energy density and speed of sound for
quark matter, we define distinct ranges of transition pressures based on the allowed strengths of discontinuity. Below a maximum transition pressure, a range of discontinuity exists that increases as the transition pressure decreases. Thereby, we identify the loci of the limits on discontinuities as the TS existence boundaries. Based on the causality limit, the TS existence boundaries can be truncated. Strong constraints on this picture are drawn from the CET, GW170817 and NICER. Within our considered model, we computed conditional extrema surviving the adopted $2\sigma$ filters—the maximum mass for TSs to be $2.05~M_\odot$, the allowed strongest discontinuity in rest-mass density to be $7.76\rho_\mathrm{sat}$, and the upper bound on transition rest-mass density to be $4.03\rho_\mathrm{sat}$. Subsequently, we compute the implications of the stiffness of the
quark matter EoS on this picture. Different confidence levels for observational constraints are considered to assess the extent to which Maxwell-type EOSs remain compatible with the observations.
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All authors Shamim Haque, Atharva Shinde, Asim Kumar Saha, Tuhin Malik, Ritam Mallick
Cosmology and Nongalactic Astrophysics
Cosmological analysis of a viable $f(R)$ gravity model
Siqi He, Weiqiang Yang and Hangyi Jin
Since viable $f(R)$
gravity models must reconcile early-universe inflation with late-time acceleration, we specifically study the dynamical behavior of such a theory during the matter-dominated to dark-energy-dominated transition epoch. By using $y_{H}(z)$ versus $z$ and the Hubble parameter, we solved the field equations. After appropriately choosing appropriate parameter values , we plotted a series of images. We mentioned that their current values are similar to latest observations data and $\Lambda$CDM-model values. Furthermore, we plotted the fitting of the distance modulus about this model using SN Ia observation data. Therefore we find that the $f(R)$
gravity model is consistent with the SN Ia data, meanwhile, explains the late-stage acceleration of the Universe. Finally, we used various diagnostic tools including $( r, s)$, $( r, q)$, $w_{D}-w'_{D}$ plane, growth rate analysis, statefinder hierarchy and $Om(z)$-diagnostic to evaluate the observational viability of our model, we perform a systematic comparison with the standard $\Lambda$CDM. We found that evolutionary images can be clearly distinguished this model from the $\Lambda$CDM.
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High Energy Astrophysical Phenomena
GRBAlpha, VZLUSAT-2 and GRBBeta – GRB observations with CubeSats
Jakub Ripa, Marianna Dafcikova, Andras Pal et al. (+49 more)
Results from GRBAlpha, VZLUSAT-2 and GRBBeta CubeSats and their on-board gamma-ray detectors for monitoring transients are summarised in this article. GRBAlpha was a 1U CubeSat launched in March 2021 to a 550 km altitude polar orbit carrying a CsI(Tl) scintillator gamma-ray burst (GRB) detector with a sensitive range of approximately 30-900 keV. It successfully operated for over four years until June 2025 when it de-orbited. VZLUSAT-2 was a 3U CubeSat launched in January 2022 to a 535 km altitude polar orbit and de-orbited in November 2025 after almost four years of smooth operation. It carried on board two GRB detectors very similar to the one used on GRBAlpha. Both missions have detected about 360 gamma-ray transients, including over 170 long and short gamma-ray bursts (GRBs), and including the most intense GRB ever recorded GRB 221009A and the second brightest GRB 230307A. The new family member, GRBBeta 2U CubeSat, integrated at Masaryk University, was launched in July 2024 to a 580 km altitude, 62 degree inclination orbit. It has been detecting GRBs since its launch without any trouble. Gamma-ray detectors on these nanosatellites are based on CsI(Tl) scintillator readout by silicon photomultipliers (SiPMs). These missions also provide a unique opportunity to study the radiation damage of SiPMs in the low Earth orbit environment and monitor the radiation belts. We have demonstrated that CubeSats can be used in missions lasting beyond three years and routinely detect GRBs.
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All authors Jakub Ripa, Marianna Dafcikova, Andras Pal, Norbert Werner, Masanori Ohno, Laszlo Meszaros, Filip Munz, Balazs Csak, Gabor Galgoczi, Nikola Husarikova, Tomas Vitek, Pavel Kosik, Michaela Duriskova, Martin Kolar, Lea Szakszonova, Michal Pazderka, Filip Hroch, Martin Topinka, Yasushi Fukazawa, Hiromitsu Takahashi, Tsunefumi Mizuno, Masato Yokota, Jean-Paul Breuer, Kazuhiro Nakazawa, Hirokazu Odaka, Yuto Ichinohe, Peter Hanak, Miroslav smelko, Ivo Vertat, Tomas Urbanec, Ales Povalac, Miroslav Kasal, Jakub Kapus, Jan Hudec, Marcel Frajt, Maksim Rezenov, Vladimir Daniel, Petr Svoboda, Juraj Dudas, Martin Sabol, Robert Laszlo, Martin Koleda, Hsiang-Kuang Chang, Tsung-Che Liu, Chih-Hsun Lin, Chin-Ping Hu, Che-Chih Tsao, Kaustubha Sen, Chih-En Wu, Aaron Tohuvavohu, Suresh Sivanandam, Mark Barnet
Earth and Planetary Astrophysics · Cross-listed from gr-qc
Thick Lunar Crust Amplifies Deci-Hertz Gravitational-Wave Signal
Lei Zhang, Han Yan, Xian Chen et al. (+1 more)
Gravitational waves (GWs) in the $0.01\sim1$ Hz band encode unique signatures of the early universe and merging compact objects, but they are beyond the reach of existing observatories. Theoretical models suggest that the Moon could act as a resonant detector, but the unknown influence of its rugged surface and heterogeneous interior poses a challenge to the accurate modeling of its response. Here, we address this long-standing uncertainty by constructing the first high-resolution, two-dimensional model of the lunar GW response, more realistic than previous ones. We achieve this by combining high-fidelity spectral-element simulations with the analytical power of normal-mode perturbation theory, thereby resolving topographical effects down to 2 km grid spacing while maintaining the capacity to discern global free-oscillation patterns. This dual-methodology approach not only recovers the expected predominant quadrupole ($l=2$) oscillation mode, but also exposes a systematic signal amplification in thick-crust regions. This enhancement is traced by our normal-mode analysis to a mode-coupling process, in which the original quadrupolar oscillation induced by the passing GW distributes energy into a series of higher-order modes, the hybridized eigenmodes of a laterally heterogeneous Moon. In certain narrow frequency ranges, we observe up to tenfold amplification spanning into the deci-hertz band, highlighting the power of numerical simulations in resolving these structurally fine-tuned features for designing future detectors. Our work establishes the Moon as a resonant GW detector albeit its complex topographical structures, and the resulting amplification maps provide quantitative guide for the optimal landing site selection.
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All authors Lei Zhang, Han Yan, Xian Chen, Jinhai Zhang
Astrophysics of Galaxies
Simulations of multi-phase gas in and around galaxies
Max Gronke and Evan Schneider
Multiphase gas – ranging from cold molecular clouds ($\lesssim 100\,$K) to hot, diffuse
plasma ($\gtrsim 10^6\,$K) is a defining feature of the interstellar, circumgalactic, intracluster, and intergalactic media. Accurately simulating its dynamics is critical to improving our understanding of
galaxy formation and
evolution, however, due to their multi-scale and multi-physics nature, multiphase systems are highly challenging to model. In this review, we provide a comprehensive overview of numerical simulations of multiphase gas in and around
galaxies. We begin by outlining the environments where multiphase gas arises and the physical and computational challenges associated with its modeling. Key quantities that characterize multiphase gas dynamics are discussed, followed by an in-depth look at idealized setups such as turbulent mixing layers, cloud-wind interactions, thermal instability, and turbulent boxes. The review then transitions to less idealized and/or larger-scale simulations, covering radiative
supernovae bubbles, tall box simulations, isolated
galaxy models including
dwarf and Milky Way-mass systems, and cosmological zoom-in simulations, with a particular focus on simulations that enhance resolution in the
halo. Throughout, we emphasize the importance of connecting scales, extracting robust diagnostics, and comparing simulations to observations. We conclude by outlining persistent challenges and promising directions for future work in simulating the multiphase Universe.
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Solar and Stellar Astrophysics
Multi-wavelength Study of A Superflare on RS CVn-type Star HD22468 Triggered at Hard X-ray by SVOM
J. Wang, W. J. Xie, F. Cangemi et al. (+36 more)
Detection of
stellar flares at hard X-ray is still rare at the current stage. A transient was recently detected by the hard X-ray camera, ECLAIRs onboard the SVOM mission at 11:39:01.2UT on 2025, January 09. Simultaneous monitor in the optical band on the ground by SVOM/GWAC and follow-up spectroscopy enable us to confirm that the transient is caused by a superflare on HD~22468, a RS CVn-type
star. The bolometric energy released in the
flare is estimated to be $\sim7.2\times10^{37}-1.7\times10^{38}\ \mathrm{erg}$. The hard X-ray spectra of the event at the peak can be reproduced by the “apec” model of a hot
plasma with a temperature of $106^{+27}_{-22}$~MK. In the optical range, the H$\alpha$ emission-line profile obtained at $\sim1.7$ hrs after the trigger shows a bulk blueshift of $-96\pm20\ \mathrm{km\ s^{-1}}$, which can be explained by either a chromospheric evaporation or a prominence eruption. The ejected mass is estimated to be $3.9\times10^{20}$ g for the evaporating
plasma, and to be $3.2\times10^{21}\ \mathrm{g}<M_{\mathrm{p}}<8.8\times10^{21}\ \mathrm{g}$ for the erupted prominence.
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All authors J. Wang, W. J. Xie, F. Cangemi, A. Coleiro, H. L. Li, Y. Xu, X. H. Han, H. Yang, L. P. Xin, X. Mao, J. Zheng, J. J. Jin, G. W. Li, J. Rodriguez, L. Tao, B. Cordier, J. Y. Wei, P. Bacon, N. Bellemont, L. Bouchet, H. B. Cai, C. Cavet, Z. G. Dai, O. Godet, A. Goldwurm, S. Guillot, L. Huang, M. H. Huang, N. Jiang, E. W. Liang, X. M. Lu, S. Schanne, S. Le Stum, Y. L. Qiu, X. G. Wang, X. Y. Wang, C. Wu, L. Zhang, S. N. Zhang
Cosmology and Nongalactic Astrophysics · Cross-listed from nucl-th
Analysis of $M1$ capture in the $\alpha(d,\gamma)^6$Li reaction
Ergash M. Tursunov and Daniel Baye
An effective operator is exactly equivalent to the long-wavelength form of the $M1$ operator in transition
matrix elements. It allows us to analytically and numerically analyze the $M1$ contribution to the $\alpha(d,\gamma)^6$Li reaction. Isoscalar $M1$ transitions from an initial $S$ wave are shown to be forbidden in radiative capture reactions when distortion is neglected in the initial state. A calculation in a three-body model with
proton,
neutron, and a structureless $\alpha$ interacting through effective forces leads to a negligible $M1$ $S$-factor at small energies. The dominant $M1$ contribution comes from transitions from an initial $S$ wave to isospin 1 components of the $^6$Li ground state. It is suggested that using this effective $M1$ operator in other models should clarify the origin of large discrepancies between $M1$ $S$-factors appearing in the literature.
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Astrophysics of Galaxies
On the Use of Field RR Lyrae as Galactic Probes – VIII. Early Formation of the Galactic Spheroid
G. Bono, V. F. Braga, M. Fabrizio et al. (+54 more)
We introduce a new photometric catalog of RR Lyrae variables (RRLs, $\sim$300,000) mainly based on data available in public
datasets. We also present the largest and most homogeneous spectroscopic
dataset of RRLs and Blue Horizontal Branch [BHB]
stars ever collected. This includes radial velocity measurements ($\sim$16,000) and iron abundances ($\Delta$S method for 8,140 RRLs, plus 547 from literature). Elemental abundances based on high-resolution spectra are provided for 487 RRLs and 64 BHB
stars. We identified candidate RRLs associated to the main
Galactic components and their iron distribution function (IDF) becomes more metal-rich when moving from the
Halo ([Fe/H]=-1.56) to the Thick (TCD; [Fe/H]=-1.47) and Thin (TND; [Fe/H]=-0.73) disk. Furthermore,
Halo RRLs and RRLs in retrograde orbits are $\alpha$-enhanced ([$\alpha$/Fe]=0.27, $\sigma$=0.18), while TCD RRLs are either $\alpha$-enhanced ([Fe/H]$\le$-1.0) or $\alpha$-poor ([Fe/H]$>$-1.0), and TND RRLs are mainly $\alpha$-poor ([$\alpha$/Fe]=-0.01, $\sigma$=0.20). We also identified RRLs associated to the main
stellar streams (
Gaia-Sausage-Enceladus [GSE]; Sequoia, Helmi, Sagittarius) and we found that their IDFs are quite similar to
Halo RRLs. However, GSE RRLs lack the metal-poor/metal-rich tails and their $\alpha$-element distribution is quite compact. The iron radial gradient in Galactocentric distance for TND, TCD and
Halo RRLs is negative and it decreases from -0.026, to -0.010, and to -0.002 dex/kpc. The iron radial gradient based on dry
Halo (
Halo without substructures) RRLs is, within the errors, equal to the global
Halo. We also found a strong similarity between iron and [$\alpha$/Fe] radial gradients of Milky Way RRLs and M31 globular clusters throughout the full range of galactocentric distances covered by the two samples.
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All authors G. Bono, V. F. Braga, M. Fabrizio, M. Tantalo, K. Baeza-Villagra, J. Crestani, V. D'Orazi, M. Dall'Ora, M. Di Criscienzo, G. Fiorentino, M. Gholami, M. Marengo, C. E. Martínez-Vázquez, M. Monelli, J. P. Mullen, A. Nunnari, V. D. Pipwala, Z. Prudil, C. Sneden, G. Altavilla, M. Bergemann, G. Böcek Topcu, R. Buonanno, A. Calamida, E. Carretta, G. Ceci, B. Chaboyer, M. Correnti, R. da Silva, I. Ferraro, F. A. Gómez, G. Iannicola, R.-P. Kudritzki, A. Kunder, S. Kwak, M. Marconi, S. Marinoni, N. Matsunaga, F. Matteucci, A. Monachesi, I. Musella, M. G. Navarro Ovando, G. W. Preston, V. Ripepi, M. Salaris, M. Sánchez-Benavente, E. Spitoni, P. B. Stetson, F. Thévenin, I. B. Thompson, P. B. Tissera, T. Tsujimoto, E. Valenti, A. K. Vivas, A. R. Walker, M. Zoccali, A. Zocchi