The VLA Survey of the Chandra Deep Field–South. I. Overview and the Radio Data

Abstract

We report 20 and 6 cm VLA deep observations of the CDF-S including the Extended CDF-S. We discuss the radio properties of 266 cataloged radio sources, of which 198 are above a 20 cm completeness level reaching down to 43 Jy at the center of the field. Survey observations made at 6 cm over a more limited region cover the original CDF-S to a comparable level of sensitivity as the 20 cm observations. Of 266 cataloged radio sources, 52 have X-ray counterparts in the CDF-S and a further 37 have counterparts in the E-CDF-S area not covered by the 1 Ms exposure. Using a wide range of material, we have found optical or infrared counterparts for 254 radio sources, of which 186 have either spectroscopic or photometric redshifts. Three radio sources have no apparent counterpart at any other wavelength. Measurements of the 20 cm radio flux density at the position of each CDF-S X-ray source detected a further 30 radio sources above a conservative 3 detection limit. X-ray and submillimeter observations have been traditionally used as a measure of AGN and star formation activity, respectively. These new observations probe the faint end of both the star formation and radio galaxy/AGN population, as well as the connection between the formation and evolution of stars and SMBHs. Both of the corresponding gravitational and nuclear fusion driven energy sources can lead to radio synchrotron emission. AGN and radio galaxies dominate at high flux densities. Although emission from star formation becomes more prominent at the microjansky levels reached by deep radio surveys, even for the weakest sources, we still find an apparent significant contribution from low-luminosity AGN as well as from star formation.

The XMM deep survey in the CDF-S

“…The radio power at 1.4 GHz is thus ∼9.3 × 10 26 W/Hz (Bonzini et al 2012. If we adopt the measurements of the two radio lobes from Kellermann et al (2008) at 6 cm, we derive an energy index 3 of α ≈ 0.9−1.0, which is consistent with the relatively old electron populations typically expected in radio lobes.…”

“…From the analysis of VLA 20 cm (1.4 GHz) and 6 cm (4.8 GHz) maps, Miller et al (2008) and Kellermann et al (2008) report the presence of an extended radio galaxy, classified as a double Fanaroff-Riley (FRII, Fanaroff & Riley 1974), whose "centroid" corresponds to the red galaxy associated with PID352 (see Fig. 7).…”

Ly$\mathsf{\alpha}$ emitters in the GOODS-S field

“…Again, by analogy with the arguments already used for the Lynx arc (F03; Binette et al 2003;Villar-Martín et al 2004), the limit on this line ratio can be used to argue for a hot blackbody-like source rather than the hard power law spectrum associated with an AGN. The absence of detectable radio (Kellermann et al 2008) or X-ray (Giacconi et al 2002) emission from the source at very low flux levels is also evidence against an AGN interpretation.…”

Radio-faint AGN: a tale of two populations

“…More details on this and other 2 A preliminary version of this figure has been shown by Padovani et al (2014). 3 Due to a small numerical error, the number counts in Kellermann et al (2008) and, consequently, also those in Padovani et al (2009) and Padovani et al (2011), were too high by ∼ 5%. statistical techniques used in this paper can be found in Padovani et al (2011).…”