The low-redshift Lyα forest towards 3C 273

Abstract

We present an analysis of the Ly. α forest towards 3C 273 from the Space Telescope Imaging Spectrograph at ∼7 km s. -1 resolution, along with reprocessed data from the Far Ultraviolet Spectroscopic Explorer. The high ultraviolet flux of 3C 273 allows us to probe the weak, low- z absorbers. The main sample consists of 21 H i absorbers that we could discriminate to a sensitivity of the redshift density for absorbers with is ∼ 1.5σ below the mean for other lines of sight; for, it is consistent with numerical model predictions. The Doppler parameter distribution is consistent with other low- z samples. We find no evidence for a break in the column density power-law distribution to a broad Ly. α absorber is within Δv≤ 50 km s. -1 and 1.3 local-frame Mpc of two ∼ 0.5L* galaxies, with an O vi absorber ∼700 km s. -1 away, similarly close to three galaxies and indicating overdense environments. We detect clustering on the Δv < 1000 km s. -1 scale at 3.4σ significance for, consistent with the level predicted from hydrodynamical simulations, and indication for a Ly. α forest void at 0.09 < z < 0.12. We find at least two components for the z= 0.0053 Virgo absorber, but the total column is not significantly changed. © 2010 The Authors. Journal compilation © 2010 RAS.