The Hot and Energetic Universe: The close environments of supermassive black holes

Michal Dovciak, Giorgio Matt, Stefano Bianchi, Thomas Boller, Laura Brenneman, Michal Bursa, Antonino D'Ai, Tiziana di Salvo, Barbara de Marco, Rene Goosmann, Vladimir Karas, Kazushi Iwasawa, Erin Kara, Jon Miller, Giovanni Miniutti, Iossif Papadakis, Pierre-Olivier Petrucci, Gabriele Ponti, Delphine Porquet, Chris Reynolds, Guido Risaliti, Agata Rozanska, Luca Zampieri, Andreas Zezas, Andrew Young

Published 2013-06-10Version 1

Most of the action in Active Galactic Nuclei (AGN) occurs within a few tens of gravitational radii from the supermassive black hole, where matter in the accretion disk may lose up to almost half of its energy with a copious production of X-rays, emitted via Comptonization of the disk photons by hot electrons in a corona and partly reflected by the accretion disk. Thanks to its large effective area and excellent energy resolution, Athena+ contributions in the understanding of the physics of accretion in AGN will be fundamental - and unique - in many respects. It will allow us to map the disk-corona system - which is crucial to understand the mechanism of energy extraction and the relation of the corona with winds and jets - by studying the time lags between reflected and primary photons. These lags have been recently discovered by XMM-Newton, but only Athena+ will have the sensitivity required to fully exploit this technique. Athena+ will also be able e.g. to determine robustly the spin of the black hole in nearby sources (and to extend these measurements beyond the local Universe), to establish the nature of the soft X-ray components, and to map the circumnuclear matter within the AGN inner parsec with unprecedented details.