Jeremiah P. Ostriker
Dept. Astroph. Science Obs., Princeton Univ. (Princeton, New Jersey, Etats-Unis d'Amérique)
Amphithéâtre Henri Mineur, Institut d'Astrophysique de Paris
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| « Black hole accretion and radiative feedback: the dramatic effects of preheating » |
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Jeremiah P. Ostriker |
| Black holes resident in the centers of galaxies will be fed by accretion of ambient gas whenever gas reaches those central regions. This can be due to mergers, but even without mergers the evolution of the stellar populations of normal galaxies provides very large amounts of gas, as stars pass through the planetary nebula stage, with the total mass release being greater than 10^11 Msolar for normal massive ellipticals. Much of that gas will cool and fall to the centers of the systems, where it will induce starbursts and accretion events onto the central black holes. We follow these events with a high resolution hydrodynamic code, allowing for radiative transfer, supernovae and other relevant physical processes. In addition, we know the spectral output of accreting black holes and we find that the high energy output from these objects will strongly inhibit inflow, causing episodic accretion and a low "duty cycle". The simulations help us to understand many phenomena including the black hole stellar mass relation, the paucity of gas in ellipticals, the incidence of the "K+A" phenomena and the observed fact that most of the black holes found in galactic centers are in the "off" state. |
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vendredi 18 janvier 2008 - 11:00 Amphithéâtre Henri Mineur, Institut d'Astrophysique de Paris |
| Page web du séminaire / Seminar's webpage |