AAS 202nd Meeting, May 2003
Session 19 Galaxy Clusters and Intergalactic Medium
Oral, Monday, May 26, 2003, 2:00-3:30pm, 209/210

## [19.05] The Density--Width Relation of the Saturated Ly\alpha Absorption

H. Zhan (Department of Physics, University of Arizona)

We report a correlation between the mean matter density \bar{\rho} and the width w of the saturated Ly\alpha absorptions, which is well characterized by \bar{\rho}(w)=\rho0+a\ wb. This property is established using the pseudo-hydro technique (Croft et al. 1998). It provides a constraint for the inversion of the Ly\alpha forest, which encounters difficulty in the saturated region. We have done a a simple inversion of the simulated Ly\alpha forests with a Gaussian density profile. The results show that the one-dimensional mass power spectrum is well recovered on scales above 2 h-1Mpc, or, roughly k \gtrsim 0.03 km-1s, at z=3. The recovery underestimates the power on small scales, but improvement is possible with a more sophisticated algorithm.