The circumgalactic medium of high-redshift galaxies

We study the properties of the circumgalactic medium (CGM) of high-z galaxies in the metal enrichment simulations presented in Pallottini et al. At z = 4, we find that the simulated CGM gas density profiles are self-similar, once scaled with the virial radius of the parent dark matter halo. We also find a simple analytical expression relating the neutral hydrogen equivalent width (EWH i) of CGM absorbers as a function of the line-of-sight impact parameter (b). We test our predictions against mock spectra extracted from the simulations and show that the model reproduces the EWH i(b) profile extracted from the synthetic spectra analysis. When compared with available data, our CGM model nicely predicts the observed EWH i(b) in z a parts per thousand(2) 2 galaxies, and supports the idea that the CGM profile does not evolve with redshift.