Galaxy cluster virial-shock sources in eROSITA catalogs

Abstract

Following the recent identification of discrete ROSAT and radio sources associated with the virial shocks of MCXC clusters and groups, we examine if the early eROSITA-DE data release (EDR) shows virial-shock X-ray sources within its $140$ deg${}^2$ field. EDR catalog sources are stacked and radially binned around EDR catalog clusters and groups. The properties of the excess virial-shock sources are inferred statistically by comparing the virial-shock region to the field. An excess of X-ray sources is found narrowly localized at the $2.0<r/R_{500}<2.25$ normalized radii, just inside the anticipated virial shocks, of the resolved 532 clusters, for samples of both extended ($3\sigma$ for 534 sources) or bright ($3.5\sigma$ for 5820 sources; $4\sigma$ excluding the low cluster-mass quartile) sources. The excess sources are on average extended ($\sim 100$ kpc), luminous ($L_X\simeq 10^{43-44}$ erg s${}^{-1}$), and hot ($\sim$keV), consistent with infalling gaseous halos crossing the virial shock. The results agree with the stacked ROSAT-MCXC signal, showing the higher $L_X$ anticipated at EDR redshifts and a possible dependence upon host mass. Localized virial-shock spikes in the distributions of discrete radio, X-ray, and probably also $\gamma$-ray sources are new powerful probes of accretion from the cosmic web, with strong constraints anticipated with future all-sky catalogs such as by eROSITA.

4 pages, 5 figures + Appendices

References in corpus (5)

• The eROSITA Final Equatorial Depth Survey (eFEDS): The X-ray catalog
• The eROSITA Final Equatorial-Depth Survey (eFEDS): Catalog of galaxy clusters and groups
• The eROSITA Final Equatorial-Depth Survey (eFEDS): X-ray Properties and Scaling Relations of Galaxy Clusters and Groups
• Shocks in the Stacked Sunyaev-Zel'dovich Profiles of Clusters II: Measurements from SPT-SZ + Planck Compton-y Map
• Synchrotron emission from virial shocks around stacked OVRO-LWA galaxy clusters

Cited by in corpus (4)

• Excess cataloged X-ray and radio sources at galaxy-cluster virial shocks
• A Hierarchical Shock Model of Ultra-High-Energy Cosmic Rays
• Macroscopic magnetization of primordial plasma by virial shocks
• Radially polarized synchrotron from galaxy-cluster virial shocks