Column density distribution of galactic Ly alpha absorption systems

A simple consistency argument for hypothesis of the galactic halo origin of the Ly alpha forest absorption lines is advanced, based on the recent dete rmination of column-density vs. impact parameter relation for the low-redsh ift gaseous galactic haloes. It is shown that observations of neutral hydro gen absorption around luminous galaxies are consistent with the index of th e power-law column density distribution derived from statistical analyses o f large samples of high-redshift Ly alpha forest lines.