Related papers: Evidence for a Circumnuclear Disk in 1946+708
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…
We present results of VLA and VLBA observations of the 1.420 GHz neutral hydrogen absorption associated with the Compact Symmetric Object 1946+708 (z=0.101). We find significant structure in the gas on parsec scales. The peak column density…
Recent VLBI observations have identified several compact radio sources which have symmetric structures on parsec scales, and exhibit HI absorption which appears to be associated with the active nucleus. These sources are uniquely well…
We present sensitive, high resolution Very Long Baseline Array (VLBA) observations of the central 0.3 arcsec of PKS 2322-123 at 1.3 and 5 GHz. These observations reveal straight and symmetric jets emerging from both sides of an inverted…
New HI observations of the nearby radio-loud galaxies Centaurus A and B2 0258+35 show broad absorption (Delta_v=400km/s) against the unresolved nuclei. Both sources belong to the cases where blue- and redshifted absorption is observed at…
One of the most important problems in the study of AGN is understanding the detailed geometry, physics, and evolution of the central engines and their environments. The leading models involve an accretion disk and torus around a central…
We present Very Long Baseline Array (VLBA) HI absorption observations of the core region of the powerful radio galaxy Cygnus A. These data show both broad (FWHM = 231 \pm 21 km/s) and narrow (FWHM <30 km/s) velocity width absorption…
We detect the 21 cm line of neutral hydrogen in absorption at a redshift of 0.673 towards the 1 Jy radio source 1504+377. The 1504+377 radio source is located toward the center of what appears to be an inclined disk galaxy at z = 0.674. The…
Massive outflows of neutral atomic hydrogen (HI) have been observed in absorption in a number of radio galaxies and are considered a signature of AGN feedback. These outflows on kpc-scales have not been investigated in great detail as they…
Cold, neutral interstellar gas, the reservoir for star formation, is traced through the absorption of the 21-centimetre continuum radiation by neutral hydrogen (HI). Although detected in one hundred cases in the host galaxies of distant…
Using a combination of observations involving the VLA, MERLIN and global VLBI networks we have made a detailed study of the radio continuum and the neutral hydrogen (HI) kinematics and distribution within the central kiloparsec of the radio…
VLT J- to M\p-band adaptive optics observations of the Circinus Galaxy on parsec scales resolve a central bright Ks-band source with a FWHM size of 1.9 $\pm$ 0.6 pc. This source is only visible at wavelengths longward of 1.6 $\mu$m and…
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…
The radio source 4C12.50 has often been suggested to be a prime candidate for the link between ultraluminous infrared galaxies and young radio galaxies. A VLBI study of the neutral hydrogen in the nuclear regions of this object shows that…
Observations of radio absorption (free-free and 21 cm neutral hydrogen absorption) can provide important constraints on the interstellar medium (either ionised or neutral) surrounding AGN. This gas is relevant in the obscuration of the…
We present an analysis of the properties of neutral hydrogen (HI) in 248 nearby (0.02<z<0.25) radio galaxies with $S_{\rm 1.4\, GHz}>30$ mJy and for which optical spectroscopy is available. The observations were carried out with the…
Sensitive high angular and linear resolution radio images of the 240-pc radio jet in NGC4151, imaged at linear resolutions of 0.3 to 2.6 pc using the VLBA and phased VLA at 21 cm, are presented and reveal for the first time a faint, highly…
We report the results of our observations of HI absorption towards the central region of the rejuvenated radio galaxy 4C29.30 (J0840+2949) with the Giant Metrewave Radio Telescope (GMRT). The radio source has diffuse, extended emission with…
We present sensitive, high-resolution 21-cm VLBA+VLA observations of the radio jet and nuclear HI absorption in NGC 4151. The 25-mas (1.6-pc) resolution continuum image reveals a highly collimated radio jet, underlying the discrete…
We have identified a large (~200 kpc), powerful double radio source whose host galaxy is clearly a disk and most likely a spiral. This FR I radio galaxy is located very near the center of the RC 0 cluster Abell 428. The existence of such an…