Radio Emission from Galaxies in the Hubble Deep Field

Abstract

We report on sensitive radio observations made with the VLA at 8.5 GHz centered on the Hubble Deep Field (HDF). We collected data in the A, CnB, C, DnC, and D conÐgurations corresponding to angular resolutions ranging from to 10A. We detected 29 radio sources in a complete sample within 0A .3 of the HDF center and above a Ñux density limit of 9.0 kJy (5 p). Seven of these sources are located 4@ .6 within the HDF itself, while the remaining 22 sources are covered by the Hubble Ñanking Ðelds (HFFs) or ground-based optical images. All of the sources in the HDF are identiÐed with galaxies with a mean magnitude R \ 21.7, while the mean magnitude of the identiÐcations outside the HDF is R \ 22.1. One radio source in the HDF, which is just below our formal completeness level but is conÐrmed by independent 1.4 GHz observations, has no optical counterpart above the HDF limit of R \ 29. Three radio sources outside the HDF have no optical counterparts to R \ 27. Based on a radio and optical positional coincidence, we detected an additional 19 radio sources in this Ðeld (seven of which are contained in the HDF) with 6.3 kJy kJy (3.5 p) and R ¹ 25 but which are not included inThe microjansky radio sources are distributed over a wide range of redshifts (0.1 \ z \ 3) and have a typical monochromatic luminosity of about 1023 W Hz~1. The majority of the optical identiÐcations are with luminous galaxies at modest redshifts many with evidence for recent star for-, mation. The remainder are composed of a mixture of bright Ðeld elliptical galaxies and late-type galaxies with evidence of nuclear activity (LINERs and Seyfert galaxies) and nearby (z \ 0.2) Ðeld spiral galaxies. None of the radio sources in this survey are identiÐed with quasars or galactic stars.

The eMERGE Survey – I: Very Large Array 5.5 GHz observations of the GOODS-North Field

“…GOODS-N was observed previously at 1.4 GHz (Richards 2000;Muxlow et al 2005;Morrison et al 2010) and 8.5 GHz (Richards et al 1998) with the Karl G. Jansky Very Large Array (VLA). Preliminary observations at 5.5 GHz were obtained as part of the e-MERLIN commissioning (Guidetti et al 2013).…”

The Chandra Deep Field North Survey. IX. Extended X-Ray Sources

“…VLA J123725+621128.-This is one of only two VLAdetected sources in the vicinity of the HDF-N that shows extended radio emission on extragalactic scales (Richards et al 1998); the other is VLA J123644+621133 associated with source 3 and described in x 4.1. With a 1.4 GHz flux density of 6 mJy, this object is one of the brightest radio sources in the field and is classified morphologically as a WAT source.…”

“…The CDF-N has the potential to determine whether the gravitational potential wells of these apparent groups are deep enough to harbor large amounts of hot gas and dark matter. Additionally, deep radio imaging of this region has revealed two highly extended radio sources (Richards et al 1998;Muxlow et al 1999;Snellen & Best 2001); one is the Fanaroff-Riley I (FR I; Fanaroff & Riley 1974) radio galaxy VLA J123644+621133 located within the HDF-N itself, and the other is the wide-angle-tailed (WAT) source VLA J123725+621128. These two radio sources are notable because FR I galaxies, and in particular WATs, are known to reside predominantly in or near rich clusters of galaxies; extended X-ray emission associated with these particular radio sources has yet to be detected.…”

Low Frequency Science with the Square Kilometre Array

“…The integrated radio emission of normal galaxies is tightly correlated to the 60 micron radiation (Condon et al 1991), since both are linked to massive star formation activity in galactic disks. At current sensitivity levels only a very small number (seven) of the HST galaxies are detectable as radio sources (Richards et al 1998). The SKA will probe the radio continuum sky to the nanoJy level, allowing detection of disk emission from starburst galaxies to very large redshift; thereby probing the star formation activity of the early universe.…”