|Speaker:||Ezequiel Treister (University of Hawaii)|
|Title:||Super-massive Black Holes Across the Cosmic History|
|Date (JST):||Fri, Mar 04, 2011, 13:30 - 15:00|
|Place:||Seminar Room A|
It is now clear that the formation of the super-massive black hole (mass greater than a million solar masses) that can be now found in the center of most massive galaxies is directly connected to the evolution of the host galaxy. However, the details of this connection are still not well understood, in spite of significant progress in the last years. In order to fully understand galaxy formation we need to know when in the cosmic history are black holes growing more intensively, in what type of galaxies this growth is happening and what fraction of these sources are invisible at most wavelengths due to obscuration by the surrounding dusty medium.
Super-massive black holes grow by accreting surrounding matter and by mergers. In this talk, I will review observations of the density of black hole accretion from the nearby Universe at z~0 to early growth episodes at z~6, when the Universe was less than a billion years old. This is done by combining multiwavelength data ranging from infrared to soft gamma rays in both wide/shallow and narrow/deep surveys. We find that a large fraction of the black hole growth, ~75%, is obscured, and report evidence for a strong connection between significant black hole growth episodes and major galaxy mergers from z~0 to z~3. We then measure from deep optimally-stacked X-ray observations the amount of black hole growth in z=6-8 galaxies (0.7-1 billion years after the Big Bang). Finally, I will describe the impact of future deep observations at hard X-ray energies with upcoming missions like NuSTAR and Astro-H.