Simulating the WFXT sky
  We investigate the scientific impact of the Wide Field X-ray Telescope
mission. We present simulated images and spectra of X-ray sources as observed
from the three surveys planned for the nominal 5-year WFXT lifetime. The goal
of these simulations is to provide WFXT images of the extragalactic sky in
different energy bands based on accurate description of AGN populations, normal
and star forming galaxies, groups and clusters of galaxies. The images are
realized using a detailed PSF model, instrumental and physical
backgrounds/foregrounds, accurate model of the effective area and the related
vignetting effect. Thanks to this comprehensive modelization of the WFXT
properties, the simulated images can be used to evaluate the flux limits for
detection of point and extended sources, the effect of source confusion at very
faint fluxes, and in general the efficiency of detection algorithms. We also
simulate the spectra of the detected sources, in order to address specific
science topics which are unique to WFXT. Among them, we focus on the
characterization of the Intra Cluster Medium (ICM) of high-z clusters, and in
particular on the measurement of the redshift from the ICM spectrum in order to
build a cosmological sample of galaxy clusters. The end-to-end simulation
procedure presented here, is a valuable tool in optimizing the mission design.
Therefore, these simulations can be used to reliably characterize the WFXT
discovery space and to verify the connection between mission requirements and
scientific goals. Thanks to this effort, we can conclude on firm basis that an
X-ray mission optimized for surveys like WFXT is necessary to bring X-ray
astronomy at the level of the optical, IR, submm and radio wavebands as
foreseen in the coming decade.
