On the nature of MG II absorption line systems in quasars

Abstract

view Abstract Citations (13) References (40) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS On the Nature of MG II Absorption Line Systems in Quasars Drinkwater, M. J. ; Webster, R. L. ; Thomas, P. A. Abstract The results of a large R-band imaging survey of 71 bright (m_V_ < 18) quasars are presented. The quasars were chosen from published samples which have intermediate resolution optical spectroscopy available, so the presence of low redshift Mg II absorption lines can be determined. We have searched our data for galaxies close to the line-of-sight to the quasars, which we might be able to identify with the absorption systems. We find a high coincidence between galaxies very near the line-of-sight and quasars showing absorption systems in their spectra, a result consistent with other studies. These galaxies have a mean luminosity of 0.5 L_*_ (assuming they lie at the absorption redshift). The distribution of impact parameters between the galaxies and the quasars extends with a flat distribution to large radii (>30h^-1^ kpc). This suggests that the absorption systems may not be gravitationally bound to the observed galaxies, but may be part of larger extended systems. We also find a significant number of galaxies near the line-of-sight to the quasar where no absorption is seen in the quasar spectrum. The selection of our quasars is unbiased with respect to galaxies near the line-of-sight, so we can compare the observed number of absorption systems to that predicted by a simple model with a constant covering factor in Mg II absorbing gas within a maximum radius of each detected galaxy. The model is consistent with a covering factor of unity, but allowing for incompleteness in the detection of galaxies, the covering factor is less than unity. The redshifts of the galaxies are required to confirm this result. Publication: The Astronomical Journal Pub Date: September 1993 DOI: 10.1086/116689 Bibcode: 1993AJ....106..848D Keywords: Absorption Spectra; Magnesium; Quasars; Astronomical Catalogs; Astronomical Photometry; Astronomical Spectroscopy; Gravitational Effects; Image Analysis; Red Shift; Astrophysics; QUASARS: ABSORPTION LINES full text sources ADS | data products NED (248) SIMBAD (69) CDS (1)