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ACKS Seminar: Dave Spiegel (Columbia University)
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ACKS Seminar: Elena Gallo (UC Santa Barbara)
| What | ACKS |
|---|---|
| When |
22 May 08 from 04:00 pm to 05:00 pm |
| Where | CAMPUS: Phys & Astrophys Bldg., 1st fl., conf rm (102/103) |
| Contact Name | Lukasz Stawarz |
| Contact Email | stawarz@slac.stanford.edu |
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Hunting for quiescent super-massive black holes: first results from AMUSE-Virgo
State of the art cold dark matter simulation suggest that energy `feedback' from super-massive black holes could solve a number of problems faced by the hierarchical paradigm at galactic scale, such as the observed red colors of massive spheroidal galaxies. In order for black hole feedback to be effective, low-levels of prolonged activity are needed is essential to prevent the reservoir of gas from cooling and producing young stars. I will present the first Chandra results from the AGN Multiwavelength Survey of Early-type galaxies in the Virgo cluster (AMUSE-Virgo). This large program targets 100 early-type Virgo galaxies with the Chandra X-ray Observatory and Spitzer Space Telescope, with the aim to provide an unbiased census of low-level super-massive black hole activity in the local universe. The sample covers over 4 orders of magnitude in black hole mass as estimated from the mass-velocity dispersion relation, large enough that it can be divided in SMBH mass bins to test whether the nuclear activity duty cycle is mass dependent. I will report on the Chandra observations of the first 16 targets, combined with results from archival data of other, more massive, 16 targets. Hard X-ray emission from a position coincident with the galaxy nucleus is detected in 50 per cent of the galaxies, and ascribed to highly sub-Eddington accretion-powered activity from a SMBH. Two of the detected nuclei are hosted in galaxies with absolute B magnitudes fainter than -18, indicating that supermassive black holes are still being harbored in such faint, low-mass objects. Most importantly, the X-ray active fraction increases with the stellar mass of the host.
MASS: Doug Applegate