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 skydue to the intrinsically small fieldof viewof Wolter‐I X‐ray optics. High angular resolutionis neededto achievea low background per source, minimize source confusion, and distinguish point from extended objects. WFXT consists of three co‐aligned wide field X‐ray telescopeswith a 1° fieldof viewand a≲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 skyto 100–1000 times the sensitivity of the ROSATAll SkySurvey, ≳2000 deg2 to deep Chandra or XMM‐Newton sensitivity, and ≳100 deg2 to the deepest Chandra sensitivity. WFXT will generate a legacy X‐ray dataset of a half million clusters and groups of galaxies to z≈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 wi...