Astronomy and Astrophysics – Astrophysics
Scientific paper
2000-12-15
Astronomy and Astrophysics
Astrophysics
4 pages, 2 postscript figures, LaTeX, uses paspiau199.sty. to appear in "The Universe at Low Radio Frequencies", IAU Symposium
Scientific paper
WSRT observations have provided a first inventory of the incidence of HI 21 cm line absorption associated with AGN at redshifts up to z=1.0. There is a large range in line depths, from tau=0.44 to tau less than 0.001, and a substantial variety of line profiles, from Gaussians of less than ten km/s to more typically a few hundred km/s, as well as irregular and multi-peaked absorption, sometimes spanning many hundreds of km/s. The chance to detect appreciable HI absorption is greatest in the most compact radio sources, GPSs and CSOs, where it can occur in circumnuclear ``disks'' or ``tori'', as well as in gas enveloping jets and hot spots; inferred densities range at least between 10 per cubic cm and 10000 per cubic cm. But HI absorption occurs also in some CSSs, perhaps associated with jet-cloud interaction regions, and in quasars with a large optical reddening. VLBI observations at the unusual UHF frequencies of redshifted HI 21 cm can give unique ``sight''lines into the physics and evolution of young radio sources and their inner galactic medium.
No associations
LandOfFree
Associated HI in Absorbers at High Redshift does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Associated HI in Absorbers at High Redshift, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Associated HI in Absorbers at High Redshift will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-510423