The Astro-H mission

ASTRO-H is a mission of the Japan Aerospace Exploration Agency (JAXA) to be launched in 2014. It is part of a very successful scientific program dedicated to astro- physical exploration. Japanese missions dedicated to high-energy astrophysics include Hakucho (1979), Tenma (1983), Ginga (1987), ASCA (1993) and Suzaku (2005, after the launch failure of an identical mission in 2000), which is still in operation.
Like it has been the case for Suzaku, JAXA invited European astrophysicists to participate to the ASTRO-H science team and offers telescope time to the European community. In exchange, the European Space Agency encourages European participation to the development of the scientific payload of ASTRO-H. There is no European mission addressing the same, or even similar, science goals as those ASTRO-H within the expected time frame of the mission. ASTRO-H can also be viewed as a precursor to the International X-ray Observatory/Athena, a mission proposed in the framework of ESAs Cosmic Vision program and to which the collaboration presented in this proposal is envisaging significant hardware contributions of a similar nature, and even possibly going beyond it. The mission ob jectives of ASTRO-H are to study the evolution of the population of obscured supermassive black holes in active galactic nuclei, trace the growth history of the largest structures in the Universe, provide insights into the behavior of material in extreme gravitational fields, determine the spin of black holes and the equation of state of neutron stars, trace particle acceleration structures in clusters of galaxies and supernova remnants and investigate the detailed physics of jets. ASTRO-H will achieve these goals thanks to two major technological leaps:

• The first focussing optics telescope (HXT) in a hard X-ray observatory
• The first high-resolution spatially resolved spectroscopy using cryogenics detector (SXS)

The SXS Filter Wheel Development

ISDC participates in the ASTRO-H mission in collaboration with SRON (Netherlands) by developping a filter wheel for the SXS. In order to maintain the energy resolution of the detector, the X-ray counting rate needs to be kept below a few counts per second and per pixel, because of the slow time constant (~ 10 ms) of the signals. For observations of bright X-ray sources with high energy resolution, a filter wheel is an essential apparatus which controls the X-ray flux thanks to its various filters. In addition the filter wheel is equipped with electronically controlled X-ray source developed by SRON, in order to allow the monitoring of the gain of the instrument.

The filter wheel will be fairly large (around 40 cm in diameter), because of its being mounted on the optical bench middle plate, i.e. far from the focus point. Environmental conditions are standard for low-orbit missions, without any particularly hard constraints in temperature range or radiation levels.

The Astro-H European Science Support Center

ISDC hosts the Astro-H European Science Support Center. It contributes to the effort of testing, validation and documentation of the analysis software and of the calibration of the instruments. It will provide support to European astronomers for the analysis of their Astro-H data.