A Deep VLA Radio Continuum Study of the Core and Outskirts of the Coma Cluster

TL;DR

This study uses deep 1.4GHz VLA radio observations of the Coma cluster's core and outskirts to catalog radio sources, identify their optical counterparts, and analyze the properties of cluster galaxies and AGN.

Contribution

It provides the first deep radio catalog of the Coma cluster with optical identifications, revealing the radio properties of cluster ellipticals and star-forming galaxies.

Findings

Detected 1030 radio sources with high sensitivity.

Identified radio AGN in ellipticals down to specific luminosities.

Linked radio sources to star-forming galaxies with low SFRs.

Abstract

We present deep 1.4GHz Very Large Array (VLA) radio continuum observations of two ~half square degree fields in the Coma cluster of galaxies. The two fields, "Coma 1" and "Coma 3," correspond to the cluster core and southwest infall region and were selected on account of abundant pre-existing multiwavelength data. In their most sensitive regions the radio data reach 22 uJy rms per 4.4" beam, sufficient to detect (at 5-sigma) Coma member galaxies with log(L) = 20.11 W/Hz. The full catalog of radio detections is presented herein and consists of 1030 sources detected at >=5 sigma, 628 of which are within the combined Coma 1 and Coma 3 area. We also provide optical identifications of the radio sources using data from the Sloan Digital Sky Survey (SDSS). The depth of the radio observations allows us to detect AGN in cluster elliptical galaxies with Mr < -20.5 (AB magnitudes), including radio detections for all cluster ellipticals with Mr < -21.8. At fainter optical magnitudes (-20.5 < Mr <~ -19) the radio sources are associated with star-forming galaxies with star formation rates as low as 0.1 solar masses per year.