The sub-mJy radio population of the E-CDFS: Optical and infrared counterpart identification

M. Bonzini, V. Mainieri, P. Padovani, K. I. Kellermann, N. Miller, P. Rosati, P. Tozzi, S. Vattakunnel, I. Balestra, W. N. Brandt, B. Luo, Y. Q. Xue

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39 Scopus citations


We study a sample of 883sources detected in a deep Very Large Array survey at 1.4GHz 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 4Ms and 250ks 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.

Original languageEnglish (US)
Article number15
JournalAstrophysical Journal, Supplement Series
Issue number1
StatePublished - Nov 2012

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


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