The Gaseous Extent of Galaxies and the Origin of \lya Absorption Systems at z < 1

Abstract

We present initial results of a program to obtain and analyze HST WFPC2 images of galaxies in fields of HST spectroscopic target QSOs. The goal of the program is to investigate how the properties of \lya absorption systems observed in the spectra of background QSOs vary with the properties of intervening galaxies. We found that \lya absorption equivalent width depends strongly on galaxy impact parameter and galaxy B-band luminosity, and that the gaseous extent of individual galaxies scales with galaxy B-band luminosity by $r\propto L_B^{0.35\pm0.10}$.

2 pages, LATEX, with 1 ps figure, conf_iap.sty. To appear in the Proceedings of 13th IAP Colloquium (July 1-5, 1997) Structure and Evolution of the Intergalactic Medium from QSO Absorption Line Systems, ed. P. Petitjean, S. Charlot