X-ray Characterization of Galaxy Groups and Hickson Groups in COSMOS-Web to z~3.8 I. X-ray Luminosity Function Evolution

Ghassem Gozaliasl; Günther Hasinger; Gavin Leroy; Alexis Finoguenov; Fatemeh Abedini; Hollis B. Akins; Rafael C. Arango-Toro; Arif Babul; Caitlin M. Casey; Nicole E. Drakos; Andreas L. Faisst; Carter Flayhart; Maximilien Franco; Zohreh Ghaffari; Santosh Harish; Hossein Hatamnia; Olivier Ilbert; Jeyhan S. Kartaltepe; Ali Ahmad Khostovan; Maarit Korpi-Lagg; Ronaldo Laishram; Daizhong Liu; Matteo Maturi; Henry Joy McCracken; Jed McKinney; Nicolas McMahon; Lauro Moscardini; Mahdiyar Mousavi-Sadr; Jason Rhodes; Brant E. Robertson; Louise Paquereau; Rasha M. Samir; Mark Sargent; Diana Scognamiglio; Marko Shuntov; Greta Toni; Francesco Ubertosi; Eleni Vardoulaki

arXiv · 2610.02470

X-ray Characterization of Galaxy Groups and Hickson Groups in COSMOS-Web to z~3.8 I. X-ray Luminosity Function Evolution

View original source ↗Read source document ↗Export metadata ↓

Abstract

Galaxy groups are the dominant halo environment in the Universe and a sensitive laboratory for feedback and gas-cycling physics, yet a uniform, intermediate-redshift X-ray characterization of the group population has been limited by the availability of deep, wide-area imaging. We present a uniform X-ray characterization of the COSMOS-Web galaxy group population: 1,678 groups (CW-All) identified with the AMICO algorithm applied to the JWST-selected COSMOS-Web photometric catalog ($0.08 \lesssim z \lesssim 3.7$), and a parallel sample of 993 Hickson compact groups (CW-HCG; $0.08 \lesssim z \lesssim 3.82$) over $0.45~\mathrm{deg}^2$. We apply a uniform aperture-photometry X-ray pipeline to the combined Chandra and XMM-Newton COSMOS mosaic, measuring fluxes, luminosities, temperatures, and halo masses and radii for every group, together with detections, upper limits, and quality flags. We detect X-ray emission from 499 CW-All groups (29.7\%) and 332 CW-HCG groups (33.4\%) at SNR~$\geq 2.0$, and present the X-ray luminosity function in four redshift bins. The characteristic luminosity $L^\star$ rises monotonically by $\sim$1.9--2.1~dex from the lowest to highest redshift bin in both catalogs, a trend that persists under two independent cross-check binning schemes and is not explained by mass or richness selection of the detected population. A targeted search for diffuse X-ray emission from the AmicOne protocluster candidate at $2.50 \lesssim z < 3.09$ finds no statistically significant signal at the current depth. We publicly release the X-ray measurements and derived properties for both catalogs.

Explore related subjects

astro-ph.GA

Keep this discovery

Explore connections, maps & timelines

BibTeX RIS

Ghassem Gozaliasl, Günther Hasinger, Gavin Leroy, Alexis Finoguenov, Fatemeh Abedini, Hollis B. Akins, Rafael C. Arango-Toro, Arif Babul, Caitlin M. Casey, Nicole E. Drakos, Andreas L. Faisst, Carter Flayhart, Maximilien Franco, Zohreh Ghaffari, Santosh Harish, Hossein Hatamnia, Olivier Ilbert, Jeyhan S. Kartaltepe, Ali Ahmad Khostovan, Maarit Korpi-Lagg, Ronaldo Laishram, Daizhong Liu, Matteo Maturi, Henry Joy McCracken, Jed McKinney, Nicolas McMahon, Lauro Moscardini, Mahdiyar Mousavi-Sadr, Jason Rhodes, Brant E. Robertson, Louise Paquereau, Rasha M. Samir, Mark Sargent, Diana Scognamiglio, Marko Shuntov, Greta Toni, Francesco Ubertosi, Eleni Vardoulaki. 2026-10-01. X-ray Characterization of Galaxy Groups and Hickson Groups in COSMOS-Web to z~3.8 I. X-ray Luminosity Function Evolution. https://arxiv.org/abs/2610.02470

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related papers

arXiv2026

Learning to See Sharper: A Physics-Informed Artificial Intelligence Framework for Super-Resolving Galaxy Spectra

The information recoverable from galaxy spectra depends fundamentally on spectral resolution, yet assembling large samples at high resolution remains observationally expensive. We present a deep-learning framework for spectral super-resolution that enhances low-resolution galaxy spectra by a factor of $\sim$10 in resolving power ($R\sim100$ to $R\sim1000$). The model is trained on 2,858 paired JWST/NIRSpec observations from the \gls{jades} program, where low-resolution prism spectra are matched with medium-resolution grating spectra (G140M, G235M, G395M) combined into a unified reference covering $1.0-5.3μ\mathrm{m}$. Our three-stage architecture performs an initial super-resolution, infers the redshift from the coarse reconstruction, and then applies a physics-informed residual refinement that uses attention across emission-line tokens to learn inter-line relationships and predict parametric line profiles, alongside a convolutional branch for continuum corrections. Evaluated on a 20% held-out sample, the model achieves noise-limited residuals over most of the spectral range and improves the signal-to-noise ratio of key diagnostic lines including [OII], H$β$, [OIII], and H$α$. The super-resolved spectra separate features that are entirely unresolved at prism resolution, such as the [OIII] $λ\lambda4959,5007$ doublet and H$β$, in exchange for a modest retrieval of line fluxes. As a proof of concept using JWST data, this approach is readily extensible to the low-resolution grism spectroscopy that will be delivered by Euclid and the Roman Space Telescope, potentially enabling population-level diagnostics across millions of galaxy spectra that would otherwise be inaccessible at low-resolution.

astro-ph.GA↗

arXiv2026

Supernovae Ia ejecta velocities and host galaxy environments: the role of survey-selection effects

The origin of the near-maximum-light Si II $λ$6355 velocity diversity among supernovae Ia (SNe Ia) remains uncertain. Previous studies have suggested that high-velocity (HV) and normal-velocity (NV) SNe Ia occupy systematically different host galaxy environments, implying differences in their progenitor populations. We re-examine this hypothesis using a sample of 354 nearby ($z\leq0.04$) spectroscopically normal SNe Ia, comprising 239 NV and 115 HV events, identified in targeted and untargeted surveys. For each SN, we determine the host galaxy morphology, galactocentric distance, and physical size, and obtain homogeneous stellar mass estimates while assessing the influence of survey-selection effects. The Si II velocity distribution is well described by two Gaussian components, confirming the NV and HV populations. We find no statistically significant differences between the galactocentric distance, host galaxy size, or stellar mass distributions of the two velocity subgroups. The environmental trends reported in previous studies are recovered only with marginal statistical significance in the targeted subsample, whereas they disappear almost entirely in the untargeted subsample, consistent with survey-selection effects playing a major role in the previously inferred environmental differences between the NV and HV events. Our results weaken the interpretation that the observed Si II velocity diversity is primarily driven by systematic differences in the global host properties examined here. Instead, they favour a scenario in which intrinsic explosion asymmetries and viewing-angle effects account for a substantial fraction of the observed velocity diversity, without excluding a possible contribution from local environmental conditions or progenitor properties.

astro-ph.GA↗

arXiv2026

No Convincing Evidence for Tidal Binary Clusters in the Galaxy

Context. The existence of tidal binary clusters (TBCs) in the Milky Way has been repeatedly suggested using Gaia DR3 astrometry and recent catalogs of binary clusters and groups. However, the dynamical feasibility of forming truly bound binary clusters through tidal capture remains uncertain. Aims. We perform a systematic reassessment of twenty star clusters, currently claimed as members of TBCs from the catalog of binary and grouped clusters of Liu et al. (2025) to ascertain their classification. Methods. For each candidate pair, we use Gaia DR3 astrometry and photometry to perform a simultaneous and self-consistent opti mization of age, distance modulus, reddening, and metallicity. Results. Our analysis shows that all studied TBCs fail in the required physical condition that ages are compatible with independent formation. After applying strict evolutionary criteria, these systems are more naturally explained as co-eval members of primordial cluster pairs or groups rather than products of tidal capture. Conclusions. We conclude that genuine tidal binary clusters, if present in the Milky Way, must be extremely rare. This work un derscores the importance of robust age determinations and physically motivated selection criteria in future searches for dynamically assembled cluster pairs.

astro-ph.GA↗