The relation between Lyman-alpha absorbers and gas--rich galaxies in the local universe
May, 2008Citations per year
Abstract: (arXiv)
We use high-resolution hydrodynamical simulations to investigate the spatial correlation between weak (N(HI) <10^{15} cm^{-2}) Ly-alpha absorbers and gas--rich galaxies in the local universe. We confirm that Ly-alpha absorbers are preferentially expected near gas--rich galaxies and that the degree of correlation increases with the column density of the absorber. The real--space galaxy auto--correlation is stronger than the cross--correlation (correlation lengths r_{0,gg}=3.1 \pm 0.1 Mpc/h and r_{0,ag}=1.4 \pm 0.1 Mpc/h, respectively), in contrast with the recent results of Ryan-Weber (2006, RW06), and the auto--correlation of absorbers is very weak. These results are robust to the presence of strong galactic winds in the hydrodynamical simulations. In redshift--space a further mismatch arises since at small separations the distortion pattern of the simulated galaxy-absorber cross-correlation function is different from the one measured by RW06. However, when sampling the intergalactic medium along a limited number of lines--of--sight, as in the real data, uncertainties in the cross correlation estimates are large enough to account for these discrepancies. Our analysis suggests that the statistical significance of difference between the cross--correlation and auto--correlation signal in current datasets is ~ 1-sigma only.References(45)
Figures(9)