H I imaging of four quasar-galaxy pairs - The parent galaxies of low-redshift quasar absorption systems

Abstract

view Abstract Citations (70) References (47) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS H i Imaging of Four Quasar-Galaxy Pairs: The Parent Galaxies of Low-Redshift Quasar Absorption Systems Carilli, C. L. ; van Gorkom, J. H. Abstract We present observations of the neutral hydrogen in four quasar-galaxy pairs. These were selected as the only known pairs for which Ca II or Na I absorption had been detected toward the background quasar at the velocity of the foreground galaxy. In three of the four pairs H I is detected in emission from the galaxy and in absorption toward the radio quasar. In each case the absorption arises in extended neutral hydrogen associated with the galaxy, and the gas morphology indicates a recent gravitational disturbance. We conclude that the parent galaxies of low- redshift absorption-line systems are gravitationally disturbed galaxies, and that the extended gas seen in absorption toward these quasars results directly from these tidal disturbances. In the three galaxies in which H I is detected, the H I is seen along the narrow line of sight to the quasar in emission and/or absorption over a large velocity range (from more than 50 km s^-1^ to up to 250 km s^-1^ in one case). These large velocity spreads are similar to the velocity range seen in high-redshift heavy element quasar absorption-line systems (York et al. 1986). The reason for the large velocity range in the low- redshift systems is that the gas is gravitationally disturbed. We find that Ca II and Na I are good tracers of H I 21 cm absorption, which is unlike the Mg II systems but is similar to the damped Lyman- α systems. We derive upper limits to the spin temperatures in the absorbing clouds of a few hundred degrees. For 1327-206-ESO 1327-2041 the absorbing gas is associated with a "polar ring." For 0955+326-NGC 3067, the gas may also be in a "polar ring," or it may be in very extended spiral arms. For 2020-370-Klemola 31A, the absorbing gas is in the warped disk of an "ocular spiral" galaxy. For 0446-208-Anon, no H I is detected. Publication: The Astrophysical Journal Pub Date: November 1992 DOI: 10.1086/171934 Bibcode: 1992ApJ...399..373C Keywords: Absorption Spectra; Galactic Clusters; Hydrogen; Quasars; Atomic Spectra; Line Spectra; Red Shift; Astrophysics; GALAXIES: CLUSTERING; GALAXIES: QUASARS: ABSORPTION LINES; RADIO LINES: ATOMIC full text sources ADS | data products NED (7) SIMBAD (6)