THE ENVIRONMENT OF LYMAN-ALPHA ABSORBERS IN THE SIGHT LINE TOWARD 3C-273

We present new ground-based data following up on the Hubble Space Telescope discovery of low-redshift Lyalpha absorption in the sight line to the quasar 3C 273. Our goal is to investigate the relationship between the low column density absorbers and higher column density objects such as galaxies or H II regions. Narrow-band filter observations with a coronagraph show that there are no H II regions or other strong Halpha line-emitting ps within a 12 kpc radius of the line of sight to the quasar, at the velocities of three of the absorbers. Broad-band imaging in Gunn r shows that there are no dwarf galaxies at Virgo distances with absolute magnitude above MB almost-equal-to - 13.5 and within a radius of 40 kpc from the line of sight to the quasar. Finally, we present fiber spectroscopy of a complete sample of galaxies within a radius of 1-degrees, down to an apparent magnitude of B almost-equal-to 19. Analysis of this sample, combined with galaxies within 10 Mpc of the quasar line of sight taken from the literature, shows that the absorbers are definitely not distributed at random with respect to the galaxies, but also that the absorber-galaxy correlation function is not as strong as the galaxy-galaxy correlation function on large scales. We show that our data are consistent with the hypothesis that all galaxies more luminous than 0.1L* have effective cross sections [for association with absorbers whose neutral hydrogen column density (log N(HI)) is greater than 13.0] of between 0.5 and 1 Mpc. We also show a clear case of a Lyalpha absorber which has no galaxy brighter than M(B) = - 18 within a projected distance of 4.8 Mpc, and discuss the possibility that Lyalpha absorbers are destroyed in a rich galaxy environment.