In July 2008, the International X-ray Observatory (IXO) was announced to the astronomical community. IXO is an international collaboration involving members appointed by ESA, NASA and JAXA. The IXO mission supersedes the XEUS and Constellation-X mission concepts.
The X-ray sky is dominated by two kinds of source: point sources marking accreting supermassive black holes in galactic nuclei, and the extensive atmospheres of clusters of galaxies. X-ray astronomy has played a crucial role in studying both these phenomena over the last 30 years. But what is perhaps most remarkable is the discovery within the the last 10 years that these phenomena are inextricably linked, although the nature of this connection remains poorly understood. The principal science aims of IXO are to study:
To address these challenges, IXO will employ optics with 20 times more collecting area at 1 keV than any previous X-ray telescope. The focal plane instruments will deliver up to 100-fold increase in effective area for high resolution spectroscopy from 0.3-10 keV, deep spectral imaging from 0.2-40 keV over a wide field of view, unprecedented polarimetric sensitivity, and microsecond spectroscopic timing with high count rate capability. Further technical information on the IXO mission can be found here (including the most recent versions of the IXO response matrices).