The Sub-mJy Radio Population of the E-CDFS: Optical and Infrared Counterpart Identification
Abstract
We study a sample of 883 sources detected in a deep Very Large Array survey at 1.4 GHz in the Extended Chandra Deep Field South. This paper focuses on the identification of their optical and infrared (IR) counterparts. We use a likelihood-ratio technique that is particularly useful when dealing with deep optical images to minimize the number of spurious associations. We find a reliable counterpart for 95% of our radio sources. Most of the counterparts (74%) are detected at optical wavelengths, but there is a significant fraction (21%) that are only detectable in the IR. Combining newly acquired optical spectra with data from the literature, we are able to assign a redshift to 81% of the identified radio sources (37% spectroscopic). We also investigate the X-ray properties of the radio sources using the Chandra 4 Ms and 250 ks observations. In particular, we use a stacking technique to derive the average properties of radio objects undetected in the Chandra images. The results of our analysis are collected in a new catalog containing the position of the optical/IR counterpart, the redshift information, and the X-ray fluxes. It is the deepest multi-wavelength catalog of radio sources, which will be used for future study of this galaxy population.
- Publication:
-
The Astrophysical Journal Supplement Series
- Pub Date:
- November 2012
- DOI:
- 10.1088/0067-0049/203/1/15
- arXiv:
- arXiv:1209.4176
- Bibcode:
- 2012ApJS..203...15B
- Keywords:
-
- cosmology: observations;
- galaxies: active;
- galaxies: starburst;
- radio continuum: galaxies;
- Astrophysics - Cosmology and Nongalactic Astrophysics
- E-Print:
- 18 pages, 11 figures, accepted for publication in ApJS, Table 3 and 5 are available in their entirety in the ancillary data