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Physics Astrophysics

astro-ph Watch Astrophysics

Wednesday 5 November

Instrumentation and Methods for Astrophysics

The first year of LISA Galactic foreground

Riccardo Buscicchio, Federico Pozzoli, Daniele Chirico et al. (+1 more)

Galactic white-dwarf binaries play a central role in the inference model for the Laser Interferometer Space Antenna. In this manuscript, we employ the $\texttt{bahamas}$ codebase to characterize, in a global-fit fashion, the reconstruction of the Galactic foreground during the first year of observation. To account for its statistical properties, we represent the data in time–frequency domain, and characterize the effectiveness of multiple approaches, e.g. statistically viable likelihoods, sampling schemes, segmentation widths, and gaps density. Our analysis yields consistent results across, with overwhelming evidence in favor of a non-stationary model in less than a month of data. Moreover, we show robustness against the presence of additional extragalactic foregrounds, and test the suitability of our approximations on the more complex simulated data in the $\textit{Yorsh}$ data challenge.
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All authors Riccardo Buscicchio, Federico Pozzoli, Daniele Chirico, Alberto Sesana

Solar and Stellar Astrophysics

A Bow-Shock Nebula Around the Z Camelopardalis-type Cataclysmic Variable FY Vulpeculae

Howard E. Bond, Calvin Carter, Eric Coles et al. (+3 more)

We present deep images of the faint nebulosity StDr 90, which we have discovered surrounds the cataclysmic variable (CV) star FY Vulpeculae. Archival photometric and spectroscopic observations, and a new optical spectrum, confirm that FY Vul belongs to the Z Camelopardalis subclass of CVs. Our imagery, obtained by accumulating long exposures with amateur telescopes equipped with CMOS cameras, shows a prominent bow shock in the light of [O III] 5007 A, collisionally excited in front of the star as it passes through a relatively dense region in the surrounding interstellar medium (ISM). FY Vul also lies near the edge of an extended faint Halpha-emitting nebula, which we interpret as a "recombination wake," i.e., a Stromgren zone recombining after being photoionized by the star's ultraviolet radiation. FY Vul joins five other CVs known to be associated with optical bow shocks and off-center nebulae. All of them are characterized by luminous accretion disks, which drive fast winds into the ISM that produce the bow shocks.
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All authors Howard E. Bond, Calvin Carter, Eric Coles, Peter Goodhew, Jonathan Talbot, Gregory R. Zeimann

Astrophysics of Galaxies

First Detection of CH3OD in Prestellar Cores

Beatrice M. Kulterer, Asunción Fuente, Maria N. Drozdovskaya et al. (+6 more)

The isotopic ratios of deuterated methanol derived around protostars are commonly used to infer the physical conditions under which they formed in the earlier prestellar stage. However, there is a discrepancy in the ratio of the singly deuterated methanol isotopologues, CH2DOH/CH3OD, between low- and high-mass protostars, which puts into question whether prestellar isotopic ratios are generally preserved during the star- and planet-forming process. Resolving this puzzle is only made harder by the complete lack of data on this ratio in the prestellar stage. This work presents observations with the IRAM 30m telescope that securely detect CH3OD in the prestellar core L1448 in Perseus and tentatively in B213-C6 in Taurus. This work constrains the ratio of CH2DOH/CH3OD and the D/H ratios for both singly deuterated methanol isotopologues for the first time at the prestellar stage. Column densities calculated under the assumption of local thermal equilibrium lead to a CH2DOH/CH3OD ratio of 2.8-8.5 in L1448 and $\leq$ 5.7 in B213-C6. The values are marginally consistent with the statistically expected ratio of 3, but most assumptions put the values in an elevated range in line with values found around low-mass protostars. The D/H ratio in CH2DOH is between 3.6% and 6.8% in L1448 and in the range of 2.4-5.8% in B213-C6. The D/H ratio derived for CH3OD is lower, namely 1.4-4.4% in L1448 and $\leq$ 3.8% in B213-C6.
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All authors Beatrice M. Kulterer, Asunción Fuente, Maria N. Drozdovskaya, Silvia Spezzano, Gisela Esplugues, David Navarro-Almaida, Marina Rodríguez Baras, Angèle Taillard, Karin Öberg

High Energy Astrophysical Phenomena

Broad Iron Line as a Relativistic Reflection from Warm Corona in AGN

P. P. Biswas, A. Różańska, F. H. Vincent et al. (+2 more)

We present that the broad feature usually observed in X-ray spectra can be explained by a ray-traced emission from a two-slab system containing a dissipative, warm corona on top of an accretion disk in an AGN. Such an accretion flow is externally illuminated by X-ray radiation from a lamp located above a central SMBH. Thermal lines from highly ionized iron ions (FeXXV and FeXXVI), caused by both internal heating and reflection from the warm corona, can be integrated into an observed broad line profile due to the close vicinity of the SMBH. We investigate the dependence of the broad line profile by varying the SMBH spin parameter, viewing angle, lamp height, and dissipation factor. Our results introduce a new method to probe properties of the warm corona using high-resolution spectroscopic measurements. We use the photoionization code TITAN to compute local ion populations and emission line profiles, and the ray-tracing code GYOTO to include relativistic effects on the outgoing X-ray spectrum. In our models, the temperature of the inner atmosphere covering the disk can reach values of 10^7 - 10^8 K due to internal warm corona dissipation and external illumination, which is adequate for generating the highly ionized iron lines. These lines can undergo significant gravitational redshift near the black hole, leading to a prominent spectral feature centered around 6.4 keV. For all computed models, the relativistic corrections shift highly ionized iron lines to the X-ray region, usually attributed to fluorescent emission from the illuminated skin of an accretion disk. Hence, in the case of a warm corona covering the inner disk regions, the resulting theoretical line profile under strong gravity is a sum of different iron line transitions, and those originating from highly ionized iron contribute the most to the observed total line profile in AGN.
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All authors P. P. Biswas, A. Różańska, F. H. Vincent, D. Lančová, P. T. Zycki

Cosmology and Nongalactic Astrophysics

Living on the edge. A quantitative warning on boundary artifacts in the IllustrisTNG

Ana Mitrašinović

Periodic boundary conditions (PBCs) are a practical necessity in cosmological simulations, but they can also introduce numerical artifacts. We quantified the prevalence of PBC-related artifacts in the IllustrisTNG using dark-matter-deprived galaxies (DMDGs) as tracers. We found that their occurrence scales inversely with simulation volume. We demonstrated that this excess population is spatially correlated with the box edges; the smallest TNG50 box is most affected by these problems. This is a unique and irreplaceable resource for studying galaxy structure. Manual inspection confirmed abrupt, unphysical mass-loss events coincident with boundary crossings. We also highlight the challenge of disentangling numerical artifacts from genuine tidally stripped galaxies in boundary-crossing clusters in TNG100. We conclude by recommending a set of mandatory sanity checks that include positional verification, mass history analysis, and even exclusion of the buffer zone near the edges. These strategies ensure the robustness of the scientific results derived from these invaluable simulations.
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Solar and Stellar Astrophysics

Observed Joys law of Bipolar Magnetic Region tilts at the emergence supports the thin flux tube model

Anu Sreedevi, Bidya Binay Karak, Bibhuti Kumar Jha et al. (+2 more)

Bipolar sunspots, or more generally, Bipolar Magnetic Regions, BMRs, are the dynamic magnetic regions that appear on the solar surface and are central to solar activity. One striking feature of these regions is that they are often tilted with respect to the equator, and this tilt increases with the latitude of appearance, popularly known as Joys law. Although this law has been examined for over a century through various observations, its physical origin is still not established. An attractive theory that has been put forward behind Joys law is the Coriolis force acting on the rising flux tube in the convection zone, which has been studied using the thin flux tube model. However, observational support for this theory is limited. If the Coriolis force is the cause of the tilt, then we expect BMRs to hold Joys law at their initial emergence on the surface. By automatically identifying the BMRs over the last two solar cycles from high resolution magnetic observations, we robustly capture their initial emergence signatures on the surface. We find that from their appearance, BMRs exhibit tilts consistent with Joys law. This early tilt signature of BMRs suggests that the tilt is developed underneath the photosphere, driven by the Coriolis force and helical convection, as predicted by the thin flux tube model. Considerable scatter around Joys law observed during the emergence phase, which reduces in the post emergence phase, reflects the interaction of the vigorous turbulent convection with the rising flux tubes in the near surface layer.
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All authors Anu Sreedevi, Bidya Binay Karak, Bibhuti Kumar Jha, Rambahadur Gupta, Dipankar Banerjee

Astrophysics of Galaxies

Radiative transfer modeling of the low-mass proto-binary system, IRAS 4A1 and 4A2

Bratati Bhat, Ankan Das, Prasanta Gorai et al. (+1 more)

NGC 1333 IRAS4A is a well-studied low-mass sun-like proto-binary system. It has two components, A1 and A2, which are diverse according to their physical and chemical properties. We modeled this hot corino using the RATRAN radiative transfer code and explained different spectral signatures observed towards A1 and A2, specifically for CH3OH and H2CO. Our main goal is to understand the kinematical and chemical differences between A1 and A2 and to classify their dust emission and absorption properties. We considered a simple 1D spherical infalling envelope consisting of collimated outflow in the source. Recent high-resolution interferometric observations of ALMA shed new light on why the same molecular transitions towards A1 and A2 show different spectral profiles. The significant difference between spectral profiles observed towards A1 and A2 is mainly due to the dust opacity effect. Dust continuum emission toward A1 is optically thick, causing the transitions observed in absorption. Meanwhile, A2 is optically thin, leading to the observed emission profiles, and an inverse P-Cygni profile suggests the presence of an infalling envelope. Using high-resolution observations from ALMA and VLA, we expanded our model from the millimeter wavelength range to the centimeter wavelength range. This expansion demonstrates the opacity effect, which is reduced in the centimeter wavelength range, causing us to observe the lines in emission. Using our model, we reproduced the population inversion causing maser emission of methanol 44 GHz and 95 GHz transitions.
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All authors Bratati Bhat, Ankan Das, Prasanta Gorai, Dipen Sahu

Solar and Stellar Astrophysics

Dark-Matter-Powered Population III Evolution: Lifetimes, Rotation, and Quasi-Homogeneity in massive Stars

Anais Pauchet and Devesh Nandal

Population III stars supplied the first light and metals in the Universe, setting the pace of re-ionisation and early chemical enrichment. In dense haloes their evolution can be strongly influenced by the energy released when WIMPs annihilate inside the stellar core. We follow the evolution of a \(20\,M_\odot\) Population III model with the genec code, adding a full treatment of spin dependent WIMP capture and annihilation. Tracks are calculated for six halo densities from \(10^{8}\) to \(3\times10^{10}\,\mathrm{GeV\,cm^{-3}}\) and three initial rotation rates between zero and \(0.4\,v/v_{\mathrm{crit}}\). As soon as the capture product reaches \(\rho_\chi\sigma_{\mathrm{SD}}\simeq2\times10^{-28}\,\mathrm{GeV\,cm^{-1}}\), the dark-matter luminosity rivals hydrogen fusion, stretching the main-sequence lifetime from about ten million years to more than a gigayear. The extra time allows meridional circulation to smooth out differential rotation; a star that begins at \(0.4\,v/v_{\mathrm{crit}}\) finishes core hydrogen burning with near solid-body rotation and a helium core almost twice as massive as in the dark-matter-free case. Because the nuclear timescale is longer, chemically homogeneous evolution now sets in at only \(0.2\,v/v_{\mathrm{crit}}\), rather than the \(\gtrsim0.5\,v/v_{\mathrm{crit}}\) required without WIMPs. For a star with \(0.4\,v/v_{\mathrm{crit}}\), the surface hydrogen fraction drops to \(X\!\sim\!0.27\), helium rises to \(Y\!\sim\!0.73\), and primary \(^{14}\mathrm N\) increases by four orders of magnitude at He exhaustion. Moderate rotation combined with plausible dark-matter densities can therefore drive primordial massive stars towards long-lived, quasi-homogeneous evolution with distinctive chemical and spectral signatures.
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High Energy Astrophysical Phenomena

X-Ray Observations of Old Nearby Supernovae: Constraints on Compact Object Populations and Late Interaction

Julia Ahlvind, Josefin Larsson and Dennis Alp

The properties of the population of compact objects created in core-collapse supernovae (SNe) are uncertain. X-ray observations years to decades after the explosions offer a way to gain insight into this, as hard X-ray emission from the central regions will emerge as the ejecta absorption decreases. Here we analyze and place upper limits on late-time X-ray emission in 242 nearby SNe, using 607 observations from Chandra, XMM-Newton, Swift, and NuSTAR. We use absorption models based on 3D simulations of neutrino-driven explosions to account for absorption of emission from the compact objects by the asymmetric ejecta. We detect X-ray emission from 12 SNe, including four for the first time (SN 1982R, SN 1984J, SN 1992bu, and SN 2003gk), and several of the others at later epochs than before. The X-ray spectra of these SNe are consistent with interaction with the circumstellar medium (CSM), with the possible exception of SN 1979C, which shows an additional hard component, as also noted in previous studies at earlier epochs. This emission may be due to a pulsar wind nebula. Using the upper limits in the full sample, we also perform a population synthesis to constrain the fraction of SNe that produce pulsars and the properties of the pulsars themselves. We find that pulsar populations with mean initial spin periods $\gtrsim100\rm~ ms$ are favored. Finally, we note that the high luminosities of several of the SNe with CSM interaction imply interactions with dense shells.
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Instrumentation and Methods for Astrophysics

Coherent Differential Imaging of high-contrast extended sources with VLT/SPHERE

Axel Potier, Raphaël Galicher, Pierre Baudoz et al. (+6 more)

High-contrast imaging relies on advanced coronagraphs and adaptive optics (AO) to attenuate the starlight. However, residual aberrations, especially non-common path aberrations between the AO channel and the coronagraph channel, limit the instrument performance. While post-processing techniques such as spectral or angular differential imaging (ADI) can partially address those issues, they suffer from self-subtraction and inefficiencies at small angular separations or when observations are conducted far from transit. We previously demonstrated the on-sky performance of coherent differential imaging (CDI), which offers a promising alternative. It allows for isolating coherent starlight residuals through speckle modulation, which can then be subtracted from the raw images during post-processing. This work aims to validate a CDI method on real science targets, demonstrating its effectiveness in imaging almost face-on circumstellar disks, which are typically challenging to retrieve with ADI. We temporally modulated the speckle field in VLT/SPHERE images, applying small phase offsets on the AO deformable mirror while observing stars surrounded by circumstellar material: HR 4796A, CPD-36 6759, HD 169142, and HD 163296. We hence separated the astrophysical scene from the stellar speckle field, whose lights are mutually incoherent. Combining a dozen of data frames and reference coronagraph point spread functions through a Karhunen-Loève image projection framework, we recover the circumstellar disks without the artifacts that are usually introduced by common post-processing algorithms (e.g., self-subtraction). The CDI method therefore represents a promising strategy for calibrating the effect of static and quasi-static aberrations in future direct imaging surveys. Indeed, it is efficient, does not require frequent telescope slewing, and does not introduce image artifacts to first order.
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All authors Axel Potier, Raphaël Galicher, Pierre Baudoz, Johan Mazoyer, Zahed Wahhaj, Ruben Tandon, Jonas G. Kühn, Laura Perez, Gael Chauvin

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

Oscillon decay via parametric resonance: the case of three-point scalar interactions

Siyao Li

We investigate the decay dynamics of oscillons through interactions with an external scalar field. To examine how robust the decay dynamics of oscillons via parametric resonance we previously found in Li et al. 2025 are to the specific form of the coupling, we extend the analysis to include a three-point interaction $g_3\phi\chi^2$. We compute the Floquet exponents of the external field $\chi$ under an oscillating oscillon background and analyze how the instability bands depend on the coupling constants and the oscillon shapes. Numerical simulations of the two-field system show that, similar to the four-point case, the parametric resonance may cease before the oscillon is destroyed, leaving a smaller oscillon that decays only perturbatively. This indicates that the partial decay of oscillons through parametric resonance is a generic phenomenon of oscillon-scalar couplings, qualitatively insensitive to the specific interaction form, while the shape of instability bands, parameter dependence, and the precise critical oscillon energies depend on the specific coupling. Our findings provide further insights into the decay dynamics of oscillons and their potential role in the post-inflationary reheating process.
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Solar and Stellar Astrophysics

Evolution of the Shock Properties of the 2023 March 13 Event from In-Situ and Remote-Sensing Data

Federica Chiappetta, Giuseppe Nisticò, Massimo Chimenti et al. (+6 more)

Shocks driven by coronal mass ejections (CMEs) are the most powerful accelerators of gradual solar energetic particles (SEPs) in the inner heliosphere. On 2023 March 13, a halo CME, as seen from the Solar Heliospheric Observatory (SoHO) and the Sun TErrestrial Relations Observatory (STEREO), gave rise to a strong SEP event. In this work, we aim to analyze this CME-driven shock from multiple spacecraft, using both remote sensing observations from STEREO-A/COR2 and in-situ data from Parker Solar Probe (PSP), Solar Orbiter (SolO), and Wind. In order to determine its direction of propagation and kinematic properties, we model the shock geometry using STEREO-A/COR2 and SoHO/LASCO/C3 observations as an expanding ellipsoid. The density compression ratio of the shock is determined by fitting the brightness profile from the coronagraphic images with that obtained from raytracing simulations of a double-Gaussian shock density profile. We compare physical quantities such as compression ratio and Alfvénic Mach number derived from remote sensing observations with in-situ measurements by PSP, SolO, STEREO-A, and Wind. From STEREO-A/COR2, we determine the compression ratio around the entire shock front in the corona, finding significant non-homogeneities that can impact the values found during in-situ crossings. Following the evolution of the parameters characterizing the CME from the source to space, we find that closer to the Sun, both the gas compression ratio and the Alfvénic Mach number remain almost constant, while they increase at larger radial distances. This indicates a non-trivial evolution of the shock parameters during its journey through the interplanetary space.
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All authors Federica Chiappetta, Giuseppe Nisticò, Massimo Chimenti, Andrea Larosa, Francesco Malara, Francesco Pucci, Luca Sorriso-Valvo, Gaetano Zimbardo, Silvia Perri

High Energy Astrophysical Phenomena

First Associated Neutrino Search for a Failed Supernova Candidate with Super-Kamiokande

F. Nakanishi, K. Abe, S. Abe et al. (+243 more)

In 2024, a failed supernova candidate, M31-2014-DS1, was reported in the Andromeda galaxy (M31), located at a distance of approximately 770 kpc. In this paper, we search for neutrinos from this failed supernova using data from Super-Kamiokande (SK). Based on the estimated time of black hole formation inferred from optical and infrared observations, we define a search window for neutrino events in the SK data. Using this window, we develop a dedicated analysis method for failed supernovae and apply it to M31-2014-DS1, by conducting a cluster search using the timing and energy information of candidate events. No significant neutrino excess is observed within the search region. Consequently, we place an upper limit on the electron antineutrino luminosity from M31-2014-DS1 and discuss its implications for various failed SN models and their neutrino emission characteristics. Despite the 18 MeV threshold adopted to suppress backgrounds, the search remains sufficiently sensitive to constrain the Shen-TM1 EOS, yielding a 90% confidence level upper limit of 1.76 \times 10^{53} erg on the electron antineutrino luminosity, slightly above the expected value of 1.35 \times 10^{53} erg.
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All authors F. Nakanishi, K. Abe, S. Abe, Y. Asaoka, M. Harada, Y. Hayato, K. Hiraide, K. Hosokawa, T. H. Hung, K. Ieki, M. Ikeda, J. Kameda, Y. Kanemura, Y. Kataoka, S. Miki, S. Mine, M. Miura, S. Moriyama, M. Nakahata, S. Nakayama, Y. Noguchi, G. Pronost, K. Sato, H. Sekiya, M. Shiozawa, Y. Suzuki, A. Takeda, Y. Takemoto, H. Tanaka, T. Yano, Y. Itow, T. Kajita, R. Nishijima, K. Okumura, T. Tashiro, T. Tomiya, X. Wang, P. Fernandez, L. Labarga, B. Zaldivar, B. W. Pointon, C.Yanagisawa, E. Kearns, L. Wan, T. Wester, J. Bian, B. Cortez, N. J. Griskevich, Y. Jiang, M. B. Smy, H. W. Sobel, V. Takhistov, A. Yankelevich, J. Hill, M. C. Jang, S. H. Lee, D. H. Moon, R. G. Park, B. S. Yang, B. Bodur, K. Scholberg, C. W. Walter, A. Beauchêne, Le Blévec, O. Drapier, A. Ershova, M. Ferey, Th. A. Mueller, A. D. Santos, P. Paganini, C. Quach, R. Rogly, T. Nakamura, J. S. Jang, R. P. Litchfield, L. N. Machado, F. J. .P Soler, J. G. Learned, K. Choi, S. Cao, L. H. V. Anthony, N. W. Prouse, M. Scott, Y. Uchida, V. Berardi, N. F. Calabria, M. G. Catanesi, N. Ospina, E. Radicioni, A. Langella, G. De Rosa, G. Collazuol, M. Feltre, M. Mattiazzi, L. Ludovici, M. Gonin, L. L. Périssé, B. Quilain, S. Horiuchi, A. Kawabata, M. Kobayashi, Y. M. Liu, Y. Maekawa, Y. Nishimura, R. Akutsu, M. Friend, T. Hasegawa, Y. Hino, T. Ishida, T. Kobayashi, M. Jakkapu, T. Matsubara, T. Nakadaira, Y. Oyama, A. Portocarrero Yrey, K. Sakashita, T. Sekiguchi, T. Tsukamoto, N. Bhuiyan, G. T. Burton, F. Di Lodovico, J. Gao, T. Katori, R. Kralik, N. Latham, R. M. Ramsden, H. Ito, T. Sone, A. T. Suzuki, Y. Takeuchi, S. Wada, H. Zhong, J. Feng, L. Feng, S. Han, J. Hikida, J. R. Hu, Z. Hu, M. Kawaue, T. Kikawa, T. V. Ngoc, T. Nakaya, R. A. Wendell, S. J. Jenkins, N. McCauley, A. Tarrant, M. Fan`{\i}, M. J. Wilking, Z. Xie, Y. Fukuda, H. Menjo, Y. Yoshioka, J. Lagoda, M. Mandal, J. Zalipska, M. Mori, J. Jiang, K. Hamaguchi, H. Ishino, Y. Koshio, T. Tada, T. Ishizuka, G. Barr, D. Barrow, L. Cook, S. Samani, D. Wark, A. Holin, F. Nova, S. Jung, J. Yoo, J. E. P. Fannon, L. Kneale, M. Malek, J. M. McElwee, T. Peacock, P. Stowell, M. D. Thiesse, L. F. Thompson, H. Okazawa, S. M. Lakshmi, E. Kwon, M. W. Lee, J. W. Seo, I. Yu, Y. Ashida, A. K. Ichikawa, K. D. Nakamura, S. Goto, H. Hayasaki, S. Kodama, Y. Kong, Y. Masaki, Y. Mizuno, T. Muro, K. Nakagiri, Y. Nakajima, N. Taniuchi, M. Yokoyama, P. de Perio, S. Fujita, C. Jesús-Valls, K. Martens, Ll. Marti, K. M. Tsui, M. R. Vagins, J. Xia, M. Kuze, S. Izumiyama, R. Matsumoto, R. Asaka, M. Ishitsuka, M. Sugo, M. Wako, K. Yamauchi, Y. Nakano, F. Cormier, R. Gaur, M. Hartz, A. Konaka, X. Li, B. R. Smithers, S. Chen, Y. Wu, B. D. Xu, A. Q. Zhang, B. Zhang, H. Adhikary, M. Girgus, P. Govindaraj, M. Posiadala-Zezula, Y. S. Prabhu, S. B. Boyd, R. Edwards, D. Hadley, M. Nicholson, M. O'Flaherty, B. Richards, A. Ali, B. Jamieson, C. Bronner, D. Horiguchi, A. Minamino, Y. Sasaki, R. Shibayama, R. Shimamura

High Energy Astrophysical Phenomena

Measuring accretion disc properties in the transitional millisecond pulsar PSR J1023+0038 using XMM-Newton, NuSTAR, NICER and Chandra

Vishal Jadoliya, Mayukh Pahari, Sudip Bhattacharyya et al. (+1 more)

Whether the accretion disc in the X-ray high-mode of transitional millisecond pulsars (tMSP) reaches near the neutron star surface by penetrating the magnetosphere is a crucial question with many implications, including for continuous gravitational wave emission from the pulsar. We attempt to answer this question for the tMSP PSR J1023+0038 by segregating high-mode data and performing detailed spectral analysis using the XMM-Newton EPIC-PN+MOS1+MOS2 joint observations, XMM-Newton+NuSTAR joint observations, NICER and Chandra individual observations during different epochs. With the sum of longest exposures ($\sim$202 ksec of high mode data from $\sim$364 ksec of total exposure), we performed a self-consistent spectral analysis and constrain the inner disc radius 16.8 $\pm$ 3.8 km with at least 3$\sigma$ significance. Such a measurement is found consistent with best-fit spectral values of inner disc radius from other observatory like NICER and a joint observations with XMM-Newton and NuSTAR within 3$\sigma$ limits. We also detect a Fe emission line at 6.45 keV, for the first time from a tMSP, in the Chandra spectrum with 99% significance with an upper limit of the inner disc radius of 21 R$_g$, supporting independently the fact that inner disc extends into neutron stars's magnetosphere during high mode. All results from our analysis imply that the accretion disc is significantly present and extended within the corotation radius of the neutron star in PSR J1023+0038 during the X-ray high-mode of the tMSP PSR J1023+0038. The measured range of inner disc radius is fully consistent with an independent analysis by Bhattacharyya (2020), which suggests continuous gravitational wave emission from this neutron star, and the standard model of X-ray pulsations in accreting MSPs.
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All authors Vishal Jadoliya, Mayukh Pahari, Sudip Bhattacharyya, Shaswat Suresh Nair

Instrumentation and Methods for Astrophysics

Design and Implementation of the Fast Data Processing System for the Baikal-GVD Neutrino Telescope

V. A. Allakhverdyan, A. D. Avrorin, A. V. Avrorin et al. (+66 more)

We present a fast data processing system for the Baikal-GVD neutrino telescope, designed for rapid identification of astrophysical neutrino events. Leveraging Baikal-GVD's modular cluster architecture, the system implements parallelized file processing where raw data files undergo concurrent analysis across dedicated virtual machines. The system implements two pipelines: a fast per-file processing and a fully fledged (per-run) processing, which integrates dynamic detector geometry determined from acoustic and inertial positioning systems and data quality monitoring with a latency of about 27 hr. The fast processing pipeline delivers a total latency of about 1.5-18 minutes from event detection to reconstructed data availability, depending on water luminescence levels. This enables fast follow-up observations of transient astrophysical sources, fulfilling Baikal-GVD's role in multi-messenger networks. The article also highlights key features of the data acquisition system, the integration of advanced synchronization systems and a robust infrastructure for data handling and storage, ensuring efficient and reliable operation of the Baikal-GVD telescope.
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All authors V. A. Allakhverdyan, A. D. Avrorin, A. V. Avrorin, V. M. Aynutdinov, I. A. Belolaptikov, Z. Berusova, E. A. Bondarev, I. V. Borina, N. M. Budnev, V. A. Chadymov, A. S. Chepurnov, V. Y. Dik, A. N. Dmitriyeva, G. V. Domogatsky, A. A. Doroshenko, R. Dvornicky, A. N. Dyachok, Zh.-A. M. Dzhilkibaev, E. Eckerova, T. V. Elzhov, V. N. Fomin, A. R. Gafarov, K. V. Golubkov, T. I. Gress, K. G. Kebkal, V. K. Kebkal, I. Kharuk, S. S. Khokhlov, E. V. Khramov, M. M. Kolbin, S. O. Koligaev, K. V. Konischev, A. V. Korobchenko, A. P. Koshechkin, V. A. Kozhin, M. V. Kruglov, V. F. Kulepov, A. A. Kulikov, Y. E. Lemeshev, M. V. Lisitsin, S. V. Lovtsov, R. R. Mirgazov, D. V. Naumov, A. S. Nikolaev, I. A. Perevalova, A. A. Petrukhin, D. P. Petukhov, E. N. Pliskovsky, M. I. Rozanov, E. V. Ryabov, G. B. Safronov, B. A. Shaybonov, V. Y. Shishkin, E. V. Shirokov, F. Simkovic, A. E. Sirenko, A. V. Skurikhin, A. G. Solovjev, M. N. Sorokovikov, I. Stekl, A. P. Stromakov, O. V. Suvorova, V. A. Tabolenko, V. I. Tretyak, B. B. Uizutuev, Y. V. Yablokova, D. N. Zaborov, S. I. Zavyalov, D. Y. Zvezdov

High Energy Astrophysical Phenomena

Stellar critical parameters in the uniform density approximation

G. S. Bisnovatyi-Kogan and E. A. Patraman

Stellar models are calculated in the approximation of a uniform density distribution. Variational method was used for determination of the boundary of a stability loss, for stellar masses in the range from 2 up to $10^5$ $M_{\odot}$. The effects of the general relativity had been taken into account. The equation of state in the temperature and density ranges $10^9 < T < 10^{10} K$, $10^5 < \rho < 10^{10}\,\frac{g}{cm^3}$ had been taken from the work of Imshennik and Nadyozhin (1965). The critical parameters for the values of entropy and stellar masses differ from more accurate values, obtained using a more complicated variant of accepted density distribution, not more than 12$\%$.
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Cosmology and Nongalactic Astrophysics

The subtle statistics of the distance ladder: On the distance prior and selection effects

Harry Desmond, Richard Stiskalek, José Antonio Nájera et al. (+1 more)

Statistical methodology is rarely considered significant in distance-ladder studies or a potential contributor to the Hubble tension. We suggest it should be, highlighting two appreciable issues. First, astronomical distances are inferred latent parameters, requiring a prior. We show that the (often implicit) uniform priors on distance moduli common to Bayesian distance-ladder analyses bias distances low due to objects being uniformly distributed in volume, which biases the Hubble constant high. Frequentist $\chi^2$ methods are unbiased for volume- or redshift-limited samples only if the redshift uncertainty (including peculiar velocities) vanishes, though simulation-based calibration can correct the bias. Second, in a Bayesian framework, selection effects introduce additional posterior factors describing the probability of objects entering the sample under the model. These partly counteract the volume prior, depending on the nature of the selection. After detailed analytic and mock-based studies, we quantify the volume-prior effect in the CosmicFlows-4 and SH0ES samples. Both use frequentist methods, so the effect appears as a potential estimator bias rather than a missing prior. The implied Hubble constant shifts are significant but must not be applied naïvely – principled selection modelling is also required, as we investigate explicitly for CosmicFlows-4. Both effects should already be captured by the SH0ES pipeline's simulation-based bias corrections. Our work highlights the crucial need to model both distances and selection accurately, either directly in a Bayesian forward model, or via post-hoc simulation-based corrections with realistic source and selection distributions. Such modelling requires samples with known, homogeneous selection criteria, which future surveys should prioritise.
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All authors Harry Desmond, Richard Stiskalek, José Antonio Nájera, Indranil Banik

Earth and Planetary Astrophysics

Life in the dark: Potential urability of moons of rogue planets

Viktória Fröhlich and Zsolt Regály

Free-floating planets are thought to be numerous in the Galaxy and may retain their moons after ejection from their natal systems. If those satellites acquire or preserve orbital eccentricity, tidal dissipation could provide a long-lasting internal heat source, potentially creating urable environments (capable of enabling abiogenesis) in the absence of stellar radiation. We explore (i) whether moons remain bound to planets expelled by a core-collapse supernova, (ii) how the explosion reshapes their orbits, and (iii) under which circumstances tidal heating can sustain urable subsurface oceans. We carried out three-dimensional N-body simulations with an 8th-order Runge-Kutta scheme, modelling homologous stellar mass loss for progenitors of 10 M$_{\odot}$. Post-explosion orbital elements of single moons and resonant moon systems were analysed, and tidal heating power was estimated with a constant phase-lag model for several tidal dissipation functions and moon densities. All simulated moons survive the supernova and remain bound to their planets. The explosion excites moon eccentricities up to $\sim7\times10^{-4}$ and $\sim3\times10^{-3}$ for single moons of planets with circular and eccentric orbits, respectively. For resonant pairs, an eccentricity of $\leq2\times10^{-2}$ is preserved. The semi-major axis of the moons changes by $\leq0.2\%$. For 12-15% of cases – preferentially moons at $a\leq15\,R_{\mathrm{planet}}$ and with $e\geq10^{-3}$ – the specific tidal heating power lies between 0.1 and 10 times what is estimated on Europa or Enceladus, sufficient to maintain liquid oceans beneath an ice crust. Eccentricity damping timescales exceed the age of the Solar System for $a\geq10\,R_{\mathrm{planet}}$, implying billions of years of continuous heating on the moons. Such worlds represent promising targets for future searches for extraterrestrial life.
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High Energy Astrophysical Phenomena

The strong Fe K line and spin of the black-hole X-ray binary MAXI J1631-479

Andrzej A. Zdziarski, Swadesh Chand, Gulab Dewangan et al. (+5 more)

We study the transient black hole binary MAXI J1631–479 in its soft spectral state observed simultaneously by the NICER and NuSTAR instruments. Its puzzling feature is the presence of a strong and broad Fe K line, while the continuum consists of a strong disk blackbody and a very weak power-law tail. The irradiation of the disk by a power-law spectrum fitting the tail is much too weak to account for the strong line. Two solutions were proposed in the past. One invoked an intrinsic Fe K disk emission, and the other invoked disk irradiation by the returning blackbody emission. We instead find that the strong line is naturally explained by the irradiation of the disk by the spectrum from Comptonization of the disk blackbody by coronal relativistic electrons. The shape of the irradiating spectrum at $\lesssim$10 keV reflects that of the disk blackbody; it is strongly curved and has a higher flux than that of a fit with a power-law irradiation. That flux accounts for the line. While this result is independent of the physical model used for the disk intrinsic emission, the value of the fitted spin strongly depends on it. When using a Kerr disk model for a thin disk with a color correction, the fitted spin corresponds to a retrograde disk, unlikely for a Roche-lobe overflow binary. Then, a model accounting for both the disk finite thickness and radiative transfer yields a spin of $a_*\approx0.8$–0.9, which underlines the strong model-dependence of X-ray spin measurements.
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All authors Andrzej A. Zdziarski, Swadesh Chand, Gulab Dewangan, Ranjeev Misra, Michal Szanecki, Bei You, Maxime Parra, Gregoire Marcel

Earth and Planetary Astrophysics

The Distribution of Earth-Impacting Interstellar Objects

Darryl Z. Seligman, Dušan Marčeta and Eloy Peña-Asensio

In this paper we calculate the expected orbital elements, radiants, and velocities of Earth-impacting interstellar objects. We generate a synthetic population of $\sim10^{10}$ interstellar objects with M-star kinematics in order to obtain $\sim10^4$ Earth-impactors. The relative flux of impactors arriving from the direction of the solar apex and the galactic plane is enhanced by a factor of $\sim2$ relative to the mean. The fastest impactors also arrive from these directions, although Earth-impactors are generally slower than objects in the overall population. This is because the Earth-impacting subset contains a higher fraction of low-eccentricity hyperbolic objects which are more strongly affected by gravitational focusing. Earth-impacting interstellar objects are more likely to have retrograde orbits close to the ecliptic plane. A selection effect makes the distribution of inclination of Earth-impacting interstellar objects uniform/sinusoidal at low/high perihelion distances. In turn, low perihelion impactors have higher impact probability towards the ecliptic plane. The overall impactor population therefore exhibits an intermediate inclination distribution between uniform and sinusoidal. The highest velocity impacts are most likely to occur in the spring when the Earth is moving towards the solar apex. However, impacts in general are more likely to occur during the winter when the Earth is located in the direction of the antapex. Interstellar objects are more likely to impact the Earth at low latitudes close to the equator, with a slight preference for the Northern hemisphere due to the location of the apex. These distributions are independent of the assumed interstellar object number density, albedos, and size-frequency distribution and are publicly available.
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High Energy Astrophysical Phenomena · Cross-listed from hep-ph

Stellar-like Galactic center excess challenges particle dark matter

Silvia Manconi, Christopher Eckner, Francesca Calore et al. (+1 more)

The Galactic Center (GC) is potentially hosting the largest indirect signal from particle dark matter (DM), which in many well-motivated models would produce gamma rays as their final states. However, this region has often been dismissed for DM studies because of the evidence for an unexpected gamma-ray component over astrophysical backgrounds at GeV energies, firstly discovered in the data of the Fermi Large Area Telescope (LAT), the so-called Galactic Center Excess (GCE). While this was initially considered to hint at GeV thermal relics, recent work supports a GCE interpretation in terms of a stellar population of millisecond pulsar-like sources in the Galactic bulge. Building on this preference, we re-evaluate the GC as a powerful target for indirect DM searches via gamma rays. This is achieved by combining adaptive template fitting and photon-count statistical methods to assess the role of sub-threshold point sources in the observed Fermi-LAT gamma-ray counts, while minimizing the mismodeling of Galactic diffuse emission backgrounds. In a fully self-consistent way, the gamma-ray data are fitted with a mixed model comprising a DM signal and a stellar bulge, both potentially contributing to the GCE. The space left for signals from weak-scale DM particle annihilations is quantified by extracting 95% C.L. upper limits on the annihilation cross section, which, depending on the DM density profile, result in stringent limits for masses $\lesssim 300$ GeV. The robustness of our results is supported by tests on simulated data.
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All authors Silvia Manconi, Christopher Eckner, Francesca Calore, Fiorenza Donato

High Energy Astrophysical Phenomena

Electromagnetic variability from circumbinary discs around binary black holes during their post-decoupling epoch

Raphaël Mignon-Risse, Peggy Varniere and Fabien Casse

We present general-relativistic hydrodynamical simulations of inviscid circumbinary discs (CBDs) around near equal-mass binary black holes (BBH) in the binary-disc post-decoupling epoch. We use an approximate BBH spacetime with a post-Newtonian inspiral motion trajectory from ${\sim}80 (M/10^7 \mathrm{M_\odot}) \, \mbox{days}$ (separation of ${\sim}\,30$ gravitational radii) to ${\sim}100 (M/10^7 \mathrm{M_\odot}) \, \mbox{minutes}$ before merger. Initial data for the inspiral runs are produced from circular-orbits runs covering the formation timescale of the overdense {\lq}lump{\rq}, orbiting the CBD inner edge. The CBD non-axisymmetries (spiral waves and lump) lead to non-negligible angular momentum transport with effective viscosity ${\alpha_\mathrm{eff} \, {\sim} \, 10^{{-3}}{- 2\times 10}^{-2}}$. We post-process these simulations with a general-relativistic ray-tracing code to obtain synthetic observations in thermal emission. We find the lump and its associated electromagnetic (EM) modulation, already reported in the pre-decoupling epoch, to survive post-decoupling up until the end of the simulation. For LISA sources, our findings point to an active EM signature in UV during optimal gravitational wave source localization. For PTA sources and current BBH candidates detected through their optical periodicity: the lump{ in a low-viscosity CBD is a possible, though not unique, origin} for the observed periodicity.
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High Energy Astrophysical Phenomena

Search for Axion-Like Particles in High-Magnetic-Field Pulsars with NICER

Yen-Jhen Liu and Yi Yang

Axion-like particles (ALPs) can couple to photons in strong magnetic fields, producing characteristic fluctuations in X-ray spectra. Using data from NASA's Neutron Star Interior Composition Explorer (NICER), we analyzed three pulsars: PSR J2229+6114, PSR J1849-0001, and PSR B0531+21, to search for such features. Each spectrum was modeled with a sliding-window power-law fitting method to identify local deviations from the smooth continuum. From these analyses, we derived constraints on the axion-photon coupling constant $g_{a\gamma\gamma}$ assuming dipole and quadrupole magnetic field distributions. We obtain upper limits in the range $10^{-10}$–$10^{-13}\,\mathrm{GeV}^{-1}$ for ALP masses in the $0.8$–$10~\mathrm{keV}$ region.
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Earth and Planetary Astrophysics

Historic microlensing events in the euclid Galactic Bulge Survey

V. Bozza, L. Salmeri, P. Rota et al. (+47 more)

Microlensing campaigns have a long history of observations covering the Galactic bulge, where thousands of detections have been obtained, including many exoplanetary systems. The Euclid Galactic Bulge Survey represents a unique opportunity to revisit a large number of past events and attempt the lens-source resolution of known events falling in the covered area. As the analysis of individual events requires non-negligible efforts, it is important to establish priorities among all possible targets, identifying those candidates with the higher chance for a successful resolution of the lens from the source and with the highest scientific interest. Drawing from the databases of the three main microlensing surveys (OGLE, MOA and KMTNet), we compile the complete catalog of past microlensing events in the Euclid survey footprint up to year 2023, containing 7801 entries. By re-modeling all events and cross-checking with Galactic models, we estimate the relative lens-source proper motions for all events. Taking into account all uncertainties, for each microlensing event we are able to estimate the probability that the lens is separated from the source by more than a given angular distance threshold. Hence, we rank all events by their resolution probability, providing additional useful information that will guide future analyses on the most promising candidates. A particular attention is dedicated to the 51 known planetary microlensing events.
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All authors V. Bozza, L. Salmeri, P. Rota, E. Bachelet, J.-P. Beaulieu, A.A. Cole, J.C. Cuillandre, E. Kerins, I. Mcdonald, P. Mróz, M. Penny, C. Ranc, N. Rektsini, E. Thygesen, H. Verma, A. Udalski, R. Poleski, J. Skowron, M. K. Szymański, I. Soszyński, P. Pietrukowicz, S. Kozłowski, K. Ulaczyk, K.A. Rybicki, P. Iwanek, M. Wrona, M. Gromadzki, M.J. Mróz, F. Abe, D.P. Bennett, A. Bhattacharya, I.A. Bond, R. Hamada, Y. Hirao, A. Idei, S. Ishitani Silva, S. Miyazaki, Y. Muraki, T. Nagai, K. Nunota, G. Olmschenk, N.J. Rattenbury, Y.K. Satoh, T. Sumi, D. Suzuki, T. Tamaoki, S.K. Terry, P.J. Tristram, A. Vandorou, H. Yama

Cosmology and Nongalactic Astrophysics

A Case for an Inhomogeneous Einstein-de Sitter Universe

Peter Raffai, Dominika E. R. Kis, Dávid A. Ködmön et al. (+3 more)

We present a local-to-global cosmological framework in which cosmic acceleration emerges from structure formation in an inhomogeneous Einstein-de Sitter (iEdS) universe, without dark energy. The model exhibits a quasilinear coasting evolution toward an effective Milne state driven by growing inhomogeneities. We test the iEdS model with ${H_0=72.5\ \mathrm{km\ s^{-1}\ Mpc^{-1}}}$ and ${\Omega_{\mathrm{m},0}=0.272}$ using CMB, BAO, and SN Ia data. The iEdS model fits the data comparably to $\Lambda$CDM and resolves the $H_0$ tension, while yielding a cosmic age ${t_0\simeq 13.67\ \mathrm{Gyr}}$ consistent with globular-cluster estimates.
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All authors Peter Raffai, Dominika E. R. Kis, Dávid A. Ködmön, Adrienn Pataki, Rebeka L. Böttger, Gergely Dálya

Astrophysics of Galaxies

A semi-analytical mock galaxy catalog for the CSST extragalactic surveys from the Jiutian simulations

Zhenlin Tan, Lizhi Xie, Jiaxin Han et al. (+17 more)

We introduce a mock galaxy catalog built for the CSST extragalactic surveys using the primary runs of the Jiutian $N$-body simulation suites. The catalogs are built by coupling the GAlaxy Evolution and Assembly (GAEA) semi-analytical model of galaxy formation with merger trees extracted from the simulations using the Hierarchical Bound-Tracing (HBT+) algorithm. The spectral energy distributions (SEDs) and broadband magnitudes are computed using the neural-network-based stellar population synthesizer StarDuster, which is trained on radiative transfer simulations to account for detailed galaxy geometry in modeling dust obscuration. Galaxy light-cones up to $z=5$ are subsequently generated with the BLiC light-cone builder which interpolates the properties of galaxies over time using an optimized interpolation scheme. The resulting catalogs exhibit good convergence in many statistical properties of the galaxy population produced from two different resolution simulations. The catalogs reproduce a number of observed galaxy properties across a range of galaxy mass and redshift, including the stellar mass functions, the luminosity function, gas mass fraction, galaxy size-mass relation and galaxy clustering. We also present the photometric and redshift distributions of galaxies expected to be observed in the CSST surveys.
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All authors Zhenlin Tan, Lizhi Xie, Jiaxin Han, Yisheng Qiu, Fabio Fontanot, Gabriella De Lucia, Qi Guo, Qingyang Li, Jiale Zhou, Wenkang Jiang, Xin Wang, Feihong He, Chichuan Jin, Yipeng Jing, Ming Li, Xiaodong Li, Wenxiang Pei, Wenting Wang, Xiaohu Yang, Yu Yu

High Energy Astrophysical Phenomena

The First Upper Bound on the Non-Stationary Gravitational Wave Background and its Implication on the High Redshift Binary Black Hole Merger Rate

Mohit Raj Sah and Suvodip Mukherjee

The high redshift merger rate and mass distribution of black hole binaries provide a direct probe to distinguish astrophysical black holes (ABHs) and primordial black holes (PBHs), which can be studied using the Stochastic Gravitational-Wave Background (SGWB). The conventional analyses solely based on the power spectrum are limited in constraining the properties of the underlying source population under the assumption of a non-sporadic Gaussian distribution. However, recent studies have shown that SGWB is expected to be sporadic and non-Gaussian in nature, which gives rise to non-zero spectral correlation that depends on the high redshift merger rate and mass distribution of the compact objects. In this work, we present the first spectral covariance analysis of the SGWB using data from the LIGO–Virgo–KAGRA collaboration during the third and the first part of the fourth observing runs. Our analysis indicates that the current spectral correlation is consistent with non-stationary noise, yielding no detection and providing only upper bounds over the frequency range of 20 Hz to 100 Hz. This upper bound on the spectral correlation translates into a mass-distribution-dependent upper bound on the merger rate of PBHs. This provides a stringent upper bound on the PBH merger rate at high redshift and hence puts constraints on the PBH formation scenarios. In the future, detection of this signal will provide a new avenue to probe the high-redshift black hole population using gravitational waves.
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Earth and Planetary Astrophysics

Formation of Free-Floating Planets via Ejection: Population Synthesis with a Realistic IMF and Comparison to Microlensing Observations

Kangrou Guo, Shigeru Ida and Masahiro Ogihara

Microlensing observations suggest that the mass distribution of free-floating planets (FFPs) follows a declining power-law with increasing mass. The origin of such distribution is unclear. Using a population synthesis framework, we investigate the formation channel and properties of FFPs, and compare the predicted mass function with observations. Assuming FFPs originate from planet-planet scattering and ejection in single star systems, we model their mass function using a Monte Carlo based planet population synthesis model combined with N-body simulations. We adopt a realistic stellar initial mass function, which naturally results in a large fraction of planetary systems orbiting low-mass stars. The predicted FFP mass function is broadly consistent with observation: it follows the observed power-law at higher masses ($10 \lesssim m/M_\oplus < 10^4$), while at lower masses ($0.1 < m/M_\oplus \lesssim 10$) it flattens, remaining marginally consistent with the lower bound of the observational uncertainties. Low-mass, close-in planets tend to remain bound, while Neptune-like planets at wide orbits dominate the ejected population due to their large Hill radii and shallow gravitational binding. We also compare the mass distribution of bound planets with microlensing observations and find reasonably good agreement with both surveys. Our model predicts $\simeq 1.20$ ejected planets per star in the mass range of $0.33 < m/M_\oplus < 6660$, with a total FFP mass of $\simeq 17.98~M_\oplus$ per star. Upcoming surveys will be crucial in testing these predictions and constraining the true nature of FFP populations.
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Instrumentation and Methods for Astrophysics

A new broadband atmospheric dispersion corrector for HROS-TMT

Manjunath Bestha, Thirupathi Sivarani, Bachar Wehbe et al. (+7 more)

Atmospheric dispersion causes light from celestial objects with different wavelengths to refract at varying angles as it passes through Earth's atmosphere. This effect results in an elongated image at the focal plane of a telescope and diminishes fiber coupling efficiency into spectrographs. We propose an optical design that incorporates a Rotational Atmospheric Dispersion Corrector (RADC) to address the broadband dispersion encountered in the multi-object mode of the High-Resolution Optical Spectrograph (HROS) on the Thirty Meter Telescope (TMT). The RADC corrects the dispersion across the entire wavelength range (0.31-1 micron), using Amici prisms optimized for over 90% transmission efficiency and minimal angular deviation of the beam from the optical axis after dispersion correction. For enhanced accuracy, particularly in the blue region, we have, for the first time, implemented the Filippenko (1982) model in Zemax via a custom Dynamic-Link Library (DLL) file.
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All authors Manjunath Bestha, Thirupathi Sivarani, Bachar Wehbe, Amirul Hasan, Bharat Chandra P, Devika K Divakar, Athira Unni, Parvathy Menon, Arun Surya, Pallavi Saraf

Astrophysics of Galaxies

The Multiphase Circumgalactic Medium of DESI Emission-Line Galaxies at z~1.5

Ting-Wen Lan, J. Xavier Prochaska, J. Aguilar et al. (+39 more)

We study the multiphase circumgalactic medium (CGM) of emission line galaxies (ELGs) at $z\sim1.5$, traced by MgII$\lambda2796$, $\lambda2803$ and CIV$\lambda1548$, $\lambda1550$ absorption lines, using approximately 8,000 ELG-quasar pairs from the Dark Energy Spectroscopic Instrument. Our results show that both the mean rest equivalent width ($W_{0}$) profiles and covering fractions of MgII and CIV increase with ELG stellar mass at similar impact parameters, but show similar distributions when normalized by the virial radius. Moreover, warm CIV gas has a more extended distribution than cool MgII gas. The dispersion of MgII and CIV gas velocity offsets relative to the galaxy redshifts rises from $\sim100 \, \rm km \, s^{-1}$ within halos to $\sim 200 \, \rm km \, s^{-1}$ beyond. We explore the relationships between MgII and CIV $W_{0}$ and show that the two are not tightly coupled: at a fixed absorption strength of one species, the other varies by several-fold, indicating distinct kinematics between the gas phases traced by each. We measure the line ratios, FeII/MgII and CIV/MgII, of strong MgII absorbers and find that at $<0.2$ virial radius, the FeII/MgII ratio is elevated, while the CIV/MgII ratio is suppressed compared with the measurements on larger scales, both with $\sim4\, \sigma$ significance. We argue that multiphase gas that is not co-spatial is required to explain the observational results. Finally, by combining with the measurements in the literature, we show the redshift evolution of CGM properties and estimate the neutral hydrogen, metal, and dust masses in the CGM of DESI ELGs — found to be comparable to those in the ISM.
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All authors Ting-Wen Lan, J. Xavier Prochaska, J. Aguilar, S. Ahlen, A. Anand, D. Bianchi, D. Brooks, F. J. Castander, T. Claybaugh, A. de la Macorra, P. Doel, S. Ferraro, A. Font-Ribera, J. E. Forero-Romero, E. Gaztañaga, G. Gutierrez, R. Joyce, S. Juneau, R. Kehoe, T. Kisner, A. Kremin, M. Landriau, L. Le Guillou, M. Manera, A. Meisner, R. Miquel, J. Moustakas, S. Nadathur, W. J. Percival, F. Prada, I. Pérez-Ràfols, G. Rossi, E. Sanchez, D. Schlegel, M. Schubnell, H. Seo, J. Silber, D. Sprayberry, G. Tarlé, B. A. Weaver, R. Zhou, H. Zou