Work

Excess cataloged X-ray and radio sources at galaxy-cluster virial shocks

Year: 2024

Type: article

Abstract: We detect a highly significant excess of X-ray (2RXS) and radio (NVSS, GMRT, VLSSr) catalog sources when stacked around MCXC galaxy clusters and groups, narrowly confined within ≲ 100 kpc of the ∼ 2.4 R 500 virial shock radius (inferred from previous continuum stacking), with similar X-ray (∼ 4σ for 443 clusters) and radio (∼ 4σ for 485 clusters) characteristics (> 5σ joint). The excess sources show 10–100 kpc scales, LX (0.1 – 2.4 keV)≃ 1042-43 erg s-1 or νLν (ν = 1.4 GHz) ≃ 1040-41 erg s-1 luminosities, and a preferentially radial radio-polarization. The narrow localization and properties of the excess identify these sources not as AGN, often invoked speculatively for excess X-ray sources at cluster outskirts, but rather as infalling gaseous clumps interacting with the virial shock, probably galactic halos and possibly outflow remnants. The local excess of such discrete, radio-to-γ-ray sources around an object can probe its virial shock also at high redshifts and sub-cluster scales.

Source: Journal of Cosmology and Astroparticle Physics

Authors: Gideon Ilani, Kuan-Chou Hou, Uri Keshet

Institutions: Ben-Gurion University of the Negev, Institute of Astronomy and Astrophysics, Academia Sinica, Academia Sinica

Language: English

Topic: Galaxies: Formation, Evolution, Phenomena

Subfield: Astronomy and Astrophysics

Field: Physics and Astronomy

Domain: Physical Sciences

Open Access status: hybrid

Estimated APC paid: $3,135

Funder: Israel Science Foundation

Awards: G2088294977, G2837684338, G3379657711, G518288856