The B3-VLA CSS sample. VIII: New optical identifications from the Sloan Digital Sky Survey. The ultraviolet-optical spectral energy distribution of the young radio sources

Abstract

Compact steep-spectrum radio sources and giga-hertz peaked spectrum radio sources (CSS/GPS) are generally considered to be mostly young radio sources. In recent years we studied at many wavelengths a sample of these objects selected from the B3-VLA catalog: the B3-VLA CSS sample. Only ~ 60 % of the sources were optically identified. We aim to increase the number of optical identifications and study the properties of the host galaxies of young radio sources. We cross-correlated the CSS B3-VLA sample with the Sloan Digital Sky Survey (SDSS), DR7, and complemented the SDSS photometry with available GALEX (DR 4/5 and 6) and near-IR data from UKIRT and 2MASS. We obtained new identifications and photometric redshifts for eight faint galaxies and for one quasar and two quasar candidates. Overall we have 27 galaxies with SDSS photometry in five bands, for which we derived the ultraviolet-optical spectral energy distribution (UV-O-SED). We extended our investigation to additional CSS/GPS selected from the literature. Most of the galaxies show an excess of ultra-violet (UV) radiation compared with the UV-O-SED of local radio-quiet ellipticals. We found a strong dependence of the UV excess on redshift and analyzed it assuming that it is generated either from the nucleus (hidden quasar) or from a young stellar population (YSP). We also compare the UV-O-SEDs of our CSS/GPS sources with those of a selection of large size (LSO) powerful radio sources from the literature. If the major process of the UV excess is caused by a YSP, our conclusion is that it is the result of the merger process that also triggered the onset of the radio source with some time delay. We do not see evidence for a major contribution from a YSP triggered by the radio sources itself.

38 pages, 21 figures, 6 tables. Accepted for publication on A&A

References in corpus (10)

• GPS radio sources: new optical observations and an updated master list
• The properties of the young stellar populations in powerful radio galaxies at low and intermediate redshifts
• Tracing jet--ISM interaction in young AGN: correlations between [OIII] 5007 and 5-GHz emission
• Star formation in the hosts of GHz peaked spectrum and compact steep spectrum radio galaxies
• Complete identification of the Parkes half-Jansky sample of GHz peaked spectrum radio galaxies
• The 6C** sample of steep-spectrum radio sources: I - Radio data, near-infrared imaging and optical spectroscopy
• The B3-VLA CSS sample. VII: WSRT Polarisation Observations and the Ambient Faraday Medium Properties Revisited
• 4C 39.29 - extended emission around a powerful Type 2 quasar
• The host galaxies of Compact Steep Spectrum and Gigahertz-Peaked Spectrum radio sources
• Deep spectroscopy of 9C J1503+4528: a very young CSS radio source at z=0.521

Cited by in corpus (11)

• Compact steep-spectrum and peaked-spectrum radio sources
• Spectral index properties of milliJansky radio sources
• The Gamma-Ray Emitting Radio-Loud Narrow-Line Seyfert 1 Galaxy PKS 2004-447 II. The Radio View
• The Gamma-Ray Emitting Radio-Loud Narrow-Line Seyfert 1 Galaxy PKS 2004-447 I. The X-Ray View
• Pushing subarcsecond resolution imaging down to 30 MHz with the trans-European International LOFAR Telescope
• New class of Very High Energy gamma-ray emitter: radio-dark mini-shells surrounding AGN jets
• High-resolution observations of SDSS J080800.99+483807.7 in the optical and radio domains. A possible example of jet-triggered star formation
• Far-UV to mid-IR properties of nearby radio galaxies
• Young but fading radio sources: searching for remnants among compact steep-spectrum radio sources
• Angular Size-Redshift: Experiment and Calculation
• Hunting for the nature of the enigmatic narrow-line Seyfert 1 galaxy PKS 2004-447