The VLA Survey of the Chandra Deep Field South. II. Identification and host galaxy properties of submillijansky sources

TL;DR

This study identifies optical and infrared counterparts for most radio sources in the Chandra Deep Field South, revealing a shift in host galaxy types from early-type to starburst galaxies below 0.08 mJy.

Contribution

It provides a comprehensive multiwavelength identification and analysis of submillijansky radio sources, highlighting the changing nature of their host galaxies.

Findings

Majority of sources identified with optical/infrared counterparts (~95%)

Redshifts assigned to about 70% of sources, including spectroscopic and photometric

Evidence of a population shift from early-type to starburst galaxies below 0.08 mJy

Abstract

We present the optical and infrared identifications of the 266 radio sources detected at 20 cm with the Very Large Array in the Chandra Deep Field South (Kellermann et al. 2008). Using deep i-band Advanced Camera for Surveys, R-band Wide Field Imager, K-band SOFI/NTT, K-band ISAAC/VLT and Spitzer imaging data, we are able to find reliable counterparts for 254 (~95%) VLA sources. Twelve radio sources remain unidentified and three of them are ``empty fields''. Using literature and our own data we are able to assign redshifts to 186 (~70%) radio sources: 108 are spectroscopic redshifts and 78 reliable photometric redshifts. Based on the rest frame colors and morphological distributions of the host galaxies we find evidences for a change in the submillijansky radio source population: a) above ~ 0.08 mJy early-type galaxies are dominating; b) at flux densities below ~0.08 mJy, starburst galaxies become dominant.