Related papers: HI Absorption in GPS/CSS Sources

In this paper we study 21-cm absorption spectra and the corresponding emission spectra toward bright continuum sources in the test region (326deg< l < 333 deg) of the Southern Galactic Plane Survey. This survey combines the high resolution…

We have carried out a sensitive high-latitude (|b| > 15deg.) HI 21cm-line absorption survey towards 102 sources using the GMRT. With a 3-sigma detection limit in optical depth of ~0.01, this is the most sensitive HI absorption survey. We…

In this paper we further explore the implications that this has for the currently popular consensus that it is the orientation of the circumnuclear obscuring torus which determines whether absorption is present along our sight-line. The…

We present an overview of the occurrence and properties of atomic gas associated with compact radio sources at redshifts up to z=0.85. Searches for HI 21cm absorption were made with the Westerbork Synthesis Radio Telescope at UHF-high…

We present a 21-cm emission-absorption study towards extragalactic sources in the Canadian Galactic Plane Survey (CGPS). We have analyzed HI spectra towards 437 sources with S > 150 mJy, giving us a source density of 0.6 sources per square…

Hydrogen column densities inferred from X-ray absorption are typically 5 - 30 times larger than the neutral atomic hydrogen column densities derived from 21cm HI absorption toward radio-loud active galactic nuclei. Some part of the…

In the last several years, a number of compact extragalactic radio sources have been found to exhibit neutral hydrogen absorption at or near the systemic velocities of their host galaxies. Models proposed to explain this phenomenon involve…

Data from a recent Australia Telescope Compact Array (ATCA) program of multi-frequency, multi-epoch monitoring of 202 active galactic nuclei with declinations < +10 degrees have been searched for GHz Peaked Spectrum (GPS) and Compact Steep…

We report on WSRT observations of HI and OH absorption at z=0.885 towards the radio lens PKS 1830-21, mm wave transitions of several molecular species have already been observed at this redshift. At mm wavelengths the source structure is…

We present a summary of recent studies of HI absorption in radio galaxies. The results show how the absorption can be due to a variety of phenomena and how they can help us in understanding more of what is happening in and around AGNs.

By combining the data from surveys for HI 21-cm absorption at various impact parameters in near-by galaxies, we report an anti-correlation between the 21-cm absorption strength (velocity integrated optical depth) and the impact parameter.…

Compact Steep Spectrum (CSS) and Gigahertz Peaked Spectrum (GPS) sources are classes of compact, powerful, extragalactic objects. These sources are thought to be the earliest stages in the evolution of radio galaxies, capturing the ignition…

We have undertaken a survey for HI 21-cm absorption within the host galaxies of z ~ 1.2 - 1.5 radio sources, in the search of the cool neutral gas currently "missing" at z > 1. This deficit is believed to be due to the optical selection of…

We present a study, done with the Australian LBA, of HI absorption for two compact radio galaxies (PKS 1549-79 and PKS 1814-63). In both the radio galaxies, the HI appears to give us information about the environment in which the radio…

We determine the small-scale structure for a large sample of Compact Steep Spectrum (CSS) and Gigahertz Peaked Spectrum (GPS) sources and a sample of larger radio sources at 327 MHz using the technique of Inter-Planetary Scintillation (IPS)…

We present {\it Chandra} X-ray Observatory observations of Giga-Hertz Peaked Spectrum (GPS) and Compact Steep Spectrum (CSS) radio sources. The {\it Chandra} sample contains 13 quasars and 3 galaxies with measured 2-10 keV X-ray luminosity…

A search for HI absorption has been made in 23 radio galaxies using the ATCA, the VLA and the WSRT. In five galaxies HI absorption was detected. We investigate how the detection rate is distributed among galaxies with different radio and…

Recent targeted studies of associated HI absorption in radio galaxies are starting to map out the location, and potential cosmological evolution, of the cold gas in the host galaxies of Active Galactic Nuclei (AGN). The observed 21 cm…

We report the detection of HI 21-cm absorption in a member of the rare and recently discovered class of compact radio sources, 'Extremely Inverted Spectrum Extragalactic Radio Sources (EISERS)'. EISERS conceivably form a special sub-class…

Using the WSRT, we carried out shallow HI absorption observations of a flux-selected (S > 50 mJy) sample of 93 radio AGN with available SDSS redshifts between 0.02 < z < 0.23. We study the gas properties of radio AGN down to fluxes not…