A study of Lyα quasar absorbers in the nearby universe

摘要: Spectroscopy of 10 quasars obtained with the Goddard High Resolution Spectrograph (GHRS) Hubble Space Telescope (HST) is presented. In sight lines, we detect 357 absorption lines above a significance level 3 σ and 272 4.5 σ. Automated software used to identify almost all which are unresolved at GHRS G140L resolution 200 km s-1. After identifying Galactic intervening metal higher order Lyman left 139 Lyα absorbers in redshift range 0 < z 0.22 (lines within 900 s-1 geocoronal not selected). These diffuse hydrogen have column densities that mostly 1013-1015 cm-2 for an assumed Doppler parameter 30 The number density rest equivalent width 0.24 A, dN/dz = 38.3 ± 5.3, agrees well measurement from Quasar Absorption-Line Key Project. There marginal evidence cosmic variance detected among lines. A clustering analysis reveals excess nearest-neighbor line pairs on velocity scales 250-750 95%-98% confidence level. hypothesis randomly distributed space can be ruled out 99.8% No two-point correlation power (ξ 1 95% confidence). amplitudes 250-500 s-1, least 4-5 times smaller than amplitude bright galaxies. detailed comparison between nearby galaxies carried limited subset 11 where galaxy sample large contiguous volume complete MB -16. Absorbers lie preferentially regions intermediate density, but it often possible assign unique counterpart absorber. This provides no explicit support associated halos luminous We made preliminary absorption-line properties environments results hydrodynamic simulations. suggest represent or shocked gas intergalactic medium traces web large-scale structure.