Mon. Not. R. Astron. Soc., 418, 1787-1795 (2011/December-2)
H I absorption towards nearby compact radio sources.
CHANDOLA Y., SIROTHIA S.K. and SAIKIA D.J.
Abstract (from CDS):
We present the results of H I absorption measurements towards a sample of nearby compact steep-spectrum (CSS) and gigahertz-peaked spectrum (GPS) radio sources, the Compact Radio sources at Low Redshift (CORALZ) sample, using the Giant Metrewave Radio Telescope (GMRT). We observed a sample of 18 sources and find seven new detections. These sources are of lower luminosity than earlier studies of CSS and GPS objects, and we investigate any dependence of H I absorption features on radio luminosity. Within the uncertainties, the detection rates and column densities are similar to the more luminous objects, with the GPS objects exhibiting a higher detection rate than for the CSS objects. The relative velocity of the blueshifted absorption features, which may be due to jet–cloud interactions, are within ∼ -250 km/s and do not appear to extend to values over 1000 km/s seen for the more luminous objects. This could be due to the weaker jets in these objects, but requires confirmation from observations of a larger sample of sources. There appears to be no evidence of any dependence of H I column density on either luminosity or redshift, but these new detections are consistent with the inverse relation between H I column density and projected linear size.
2011 The Authors Monthly Notices of the Royal Astronomical Society2011 RAS
galaxies: active - galaxies: evolution - galaxies: jets - galaxies: nuclei - radio lines: galaxies