The Wide Field X-ray Telescope Mission-A Digital Sky Survey in X-rays

Sensitive surveys of the X-ray universe have been limited to small areas of the sky due to the intrinsically small field of view of Wolter-1 X-ray optics. High angular resolution is needed to achieve a low background per source, minimize source confusion, and distinguish point from extended objects. WFXT consists of three co-aligned wide field X-ray telescopes with a 1 degrees field of view and a less than or similar to 10 '' (goal of 5 '') angular resolution (HEW) over the full field. Total effective area at 1 keV will be > 5000 cm(-2). WFXT will perform three extragalactic surveys that will cover most of the sky to 100-1000 times the sensitivity of the ROSAT All Sky Survey, greater than or similar to 2000 deg(2) to deep Chandra or XMM-Newton sensitivity, and greater than or similar to 100 deg(2) to the deepest Chandra sensitivity. WFXT will generate a legacy X-ray dataset of a half million clusters and groups of galaxies to z approximate to 2, also characterizing the physics of the intracluster gas for a significant fraction of them, thus providing an unprecedented data set for cosmological applications; it will detect > 10(7) AGN to z > 6, again obtaining spectra for a substantial fraction, to study the growth of supermassive black holes; it will detect > 10(5) normal/starburst galaxies; and it will detect and characterize star formation regions across the Galaxy. WFXT is the only X-ray survey mission that will match, in area and sensitivity, the next generation of wide-area optical, IR and radio surveys