The remarkable absorption-line systems in the quasar Tololo 1037-27

Open Access
Publisher Website
Google Scholar
Abstract
We present the first medium-resolution spectroscopic observations of the quasar Tololo 1037–27 (zem = 2.18). We find 49 absorption lines between 3500 and 6000 Å, and identify seven absorption-line redshifts. Remarkably, six of the absorption systems are in the small redshift range zabs = 1.971 to zabs = 2.138. The two most prominent absorption systems, zabs = 2.138 and zabs = 2.082 are of high ionization and the full width at half maximum at rest and after correction for the instrumental response of their Lyα and C IV lines is in the range 600–1100 km s−1, i.e. larger than the width of lines which would be produced by absorbing material in a single galaxy. These properties, along with the high density of absorption-line systems, suggest that the Lyα and C IV lines are the superposition of several unresolved lines arising from absorption by individual galaxies in two groups or clusters of galaxies, possibly members of the same supercluster. The gas in these clusters could be influenced by the proximity of this or other quasars, which might explain the high degree of ionization of the absorbing gas. Alternatively, and perhaps less likely, the two absorption systems are intrinsic to the quasar and represent two outflows of gas. The four other absorption line systems at zabs = 2.128, 2.070, 2.028 and 1.971 respectively, show lower degrees of ionization, and velocity profiles which are consistent with them originating in intervening galaxies or clusters of galaxies. The significantly lower redshift system at zabs = 1.077 is a low-ionization intervening galaxy system. Three rather strong absorption lines, including one at a wavelength just above that of Lyα in emission, remain unidentified.

This publication has 0 references indexed in Scilit: