The main goal of my PhD project is to characterize the properties of the
intergalactic medium (IGM) around galaxies at high redshift, in order to study
the galaxy/intergalactic medium interplay. In fact, intergalactic space provides
a critical laboratory to investigate the baryon cycle that regulates star formation
and galaxy growth. First of all, the IGM is the reservoir of baryons from which
galaxies form and it is the fuel necessary for sustaining star formation, while
at the same time it is being replenished with both newly accreted intergalactic
gas and chemically enriched materials from galaxies, carrying the imprints of
galactic feedback. In this context, the IGM metal enrichment has gained a lot
of interest after the second half of the ’90s. In fact, it was originally thought
that the gas infalling onto galaxies had a primordial composition, as heavy el-
ements can be produced only inside stars and star formation is not present in
the low-density and high-temperature IGM. With the advent of high-resolution
spectroscopy around 1995, the first metal absorption lines were observed in
Quasars (QSOs) spectra, leading to the question of the mechanisms polluting
the IGM. In this thesis work, I tried to characterise the properties of the IGM
around galaxies at high redshift using hydrodynamical simulations compared
with observational data taken from the literature. In particular, with my re-
search I have shed some light on the nature of the enviroment that give rise to
the observed metal systems (in particular systems identified by the C iv and Si iv
transitions) and at the same time I have found that some of the subgrid physical
processes implemented in simulations do not have a substantial influence on the
characteristics of the IGM.
