  My Ph.D. Thesis is devoted to the study of groups and clusters of galaxies in
the X-ray band. This field has been very active in the last ten years, thanks
to the data gathered from the Chandra and XMM satellites. Clusters of galaxies
are prominent X-ray sources thanks to thermal bremsstrahlung emission from the
diffuse ICM heated to 10^7-10^8 K, which provides about 15% of their total
mass. The analysis of the X-ray emission from groups and clusters allows to
study the large scale structure of the Universe, to constrain the cosmological
parameters, and to investigate the interaction between the ICM and the cluster
galaxies. My scientific work is mainly focused on the realization of a new
X-ray survey of galaxy clusters, the SXCS, obtained from the previously
unexplored archive of the X-Ray Telescope (XRT) on board of the Swift
satellite. The goal is not only to build a new catalogue, but also to
characterize the thermodynamical and chemical properties of the brightest
groups and clusters in the survey catalogue. Moreover, given the overall
characteristics of the survey, I also expect to detect some clusters at
redshift z>1, which will have a strong impact in the study of the large scale
structure of the Universe and the cosmological parameters. During my work I
also contributed substantially to the image simulator code of a new proposed
X-ray mission submitted to the NASA Astro 2010 Decadal Survey: the Wide Field
X-ray Telescope (WFXT). This work represents an important part of the
scientific case of WFXT, since, for first time in the simulations I included
realistic populations of all the source types contributing to the extragalactic
X-ray sky, namely groups and clusters of galaxies, active galactic nuclei, and
star-forming galaxies. Thanks to this work, the scientific cases of WFXT can
now be tested on solid ground.
