A population of high-redshift type 2 quasars - II. Radio properties

Abstract

We present multi-frequency radio observations of a sample of z ~ 2 obscured (type 2) quasars in the Spitzer extragalactic First Look Survey area. We combine the public data at 1.4 GHz, used in the selection of these sources, with new observations at 610 MHz (Giant Meterwave Radio Telescope) and at 4.9 GHz (Very Large Array). We find that the sample includes sources with steep, flat and gigahertz-peaked spectra. There are no strong correlations between the presence or absence of emission lines in the optical spectra and the radio spectral properties of the sample. However, there are no secure flat-spectrum type 2 quasars with narrow emission lines which would be problematic for unified schemes. Most of the population have straight radio spectra with spectral index α ~ 1 as is expected for developed, potentially Fanaroff-Riley type I-like jets in which continuous injection of relativistic electrons is accompanied by inverse Compton losses against the cosmic microwave background. © 2006 The Authors. Journal compilation © 2006 RAS.