International X-ray Observatory (IXO)
2 August 2018
IXO is a next-generation space observatory which has been proposed as a joint project involving Europe, the United States and Japan. It is a candidate L-class (large) mission in ESA's Cosmic Vision 2015-2025 programme. In order to address some of the most fundamental questions in contemporary astrophysics and cosmology, including the behaviour of matter and energy under extreme conditions, IXO will provide major advances in X-ray imaging, timing and spectroscopy.