XEUS is the potential successor to ESA's XMM-Newton X-ray observatory and is being proposed in response to the
Cosmic Vision 2015-2025 long term plan for ESA's Science Programme. A new mission configuration was developed
in the last year, accommodating the boundary conditions of a European-led mission with a formation-flying mirror and
detector spacecraft in L2 with a focal length of 35m and an effective area of >5 m2 at 1 keV. Here the new capabilities
are compared with the key scientific questions presented to the Cosmic Vision exercise: the evolution of large scale
structure and nucleosynthesis, the co-evolution of supermassive black holes and their host galaxies, and the study of
matter under extreme conditions.
XEUS is the potential successor to ESA's XMM-Newton X-ray observatory and is being proposed in response to the Cosmic Vision 2015-2025 long term plan for ESA's Science Programme. Novel light-weight optics with an effective area of 5 m2 at 1 keV and 2 m2 at 7 keV and 2-5" HEW spatial resolution together with advanced detectors will provide much improved imaging, spectroscopic and timing performances and open new vistas in X-ray astronomy in the post 2015 timeframe. XEUS will allow the study of the birth, growth and spin of the super-massive black holes in early AGN, allow the cosmic feedback between galaxies and their environment to be investigated through the study of inflows and outflows and relativistic acceleration and allow the growth of large scale structures and metal synthesis to be probed using the hot X-ray emitting gas in clusters of galaxies and the warm/hot filamentary structures observable with X-ray absorption spectroscopy. High time resolution studies will allow the Equation of State of supra-nuclear material in neutron stars to be constrained. These science goals set very demanding requirements on the mission design which is based on two formation flying spacecraft launched to the second Earth-Sun Lagrangian point by an Ariane V ECA. One spacecraft will contain the novel high performance optics while the other, separated by the 35 m focal length, will contain narrow and wide field imaging spectrometers and other specialized instruments.
XEUS is the potential successor to ESA's XMM-Newton X-ray observatory. Novel light-weight optics with an effective area of 10 m2 at 1 keV and 2-5" HEW spatial resolution together with advanced imaging detectors will provide a sensitivity around 200 times better than XMM-Newton as well as much improved high-energy coverage, and spectroscopic performance. This enormous improvement in scientific capability will open up new vistas in X-ray astronomy. It will allow the detection of massive black holes in the earliest AGN and estimates of their mass, spin and red-shift through their Fe-K line properties. XEUS will study the first gravitationally bound, Dark Matter dominated, systems small groups of galaxies and trace their evolution into today's massive clusters. High-resolution spectroscopy of the hot intra-cluster gas will be used to investigate the evolution of metal synthesis to the present epoch. The hot filamentary structure will be studied using absorption line spectroscopy allowing the mass, temperature and density of the intergalactic medium to be characterized. As well as these studies of the deep universe, the enormous low-energy collecting area will provide a unique capability to investigate bright nearby objects with dedicated high-throughput, polarimetric and time resolution detectors.
Development of single pixel x-ray microcalorimeters at our institutes, employing superconducting-to-normal phase transition thermometers operating at about 100 mK, generally called Transition-Edge-Sensors (TES), has now resulted in an energy resolution of 3.9 eV FWHM for 5.89 keV x-rays in combination with a response time of 100 μs. Pixel arrays of these detectors, presently under development, will allow for unprecedented x-ray spectroscopy of spatially extended cosmic x-ray sources such as clusters of galaxies, supernova remnants, the galactic diffuse x-ray background and the arm-hot intergalactic medium. Optimization of these cryogenic imaging detectors around 1 keV, in combination with large-area x-ray optics, makes them the most suitable sensor for study of the formation and evolution of hot matter in the universe at large redshift. This detector concept is therefore included in the model payload of the XEUS mission, presently under study by ESA and ISAS. Smaller scale low energy x-ray spectroscopy missions could however generate significant progress in the understanding of supernova remnants, cluster of galaxies and galactic and intergalactic diffuse x-ray emission. This paper presents some science cases, which make explicit use of the unique combination of high efficiency, high spectral resolution and imaging of cryogenic x-ray imaging spectrometers. Furthermore it discusses the present development status of these imaging spectrometers at our institutes, their operating principles and expected performance figures.
XEUS: The X-ray Evolving Universe Spectroscopy mission represents a potential follow-on mission to the ESA XMM cornerstone currently nearing completion. XEUS represents the next logical step forward in x-ray astrophysics after the current set of mission have been launched and completed their operational lives. The development and ultimate success relies heavily on the capability of the International Space Station (ISS). In this paper we describe the key characteristics of the mission including the requirements placed specifically on the ISS and discuss the significant advances in high energy astrophysics expected from such an observatory.
A feasibility study of an imaging 32 by 32 pixel micro- calorimeter array, intended for the XEUS mission is presented. Three different concepts, theoretically leading to a detector that combines an energy resolution of 5 eV for 8 keV x-rays and a count rate of at least 100 counts/pixel, are presented and discussed. The starting point for this study is the current progress in the field of single pixel micro-calorimeters employing voltage biased transition edge sensors. The design concepts originate from different philosophies for the thermal design and geometrical lay-out and will use state of the art micro-machining and lithography. Moreover, both from an electrical and a cooling point of view SQUID read-out will be the challenge and grouping of pixels might be considered.