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Special ACKS Seminar: Dragan Huterer
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ACKS Seminar: Laura Ferrarese (University of Victoria)
| What | ACKS |
|---|---|
| When |
18 October 07 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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The structure of Early-Type galaxies from the ACS Virgo Cluster Survey: Cores, Stellar Nuclei and Supermassive Black Holes
Stellar and gas dynamical studies in an ever-increasing number of galaxies have established that many - and perhaps all - luminous galaxies contain central supermassive black holes (SBHs). Following the discovery that SBH masses correlate with various properties of the host galaxy - such as bulge luminosity, mass, velocity dispersion, light concentration, and halo circular velocity - it has become widely accepted not only that the presence of a SBH can affect the very structure of galaxy cores, but also that SBH and galaxy formation are closely entwined.
In this talk, I will present recent results from the ACS Virgo and Fornax cluster surveys, and probe deeper into the structure of early-type galaxies and the SBH-galaxy connection. The surveys, which targeted 100 early-type galaxies - from giants to dwarfs - in the Virgo cluster, and 43 in the Fornax cluster, represent the most complete and homogeneous imaging survey of early-type galaxies ever conducted with HST. In contrast with earlier claims, we find a continuity in structural properties when moving from faint dwarf systems to regular and giant ellipticals. Furthermore, in moving from bright to faint early-type galaxies, the surface brightness profiles within the inner few hundred parsecs undergo a systematic but smooth transition from low-density cores to high density stellar nuclei. Cores are uniquely associated with galaxies brighter than M(B) ~ -20.5 mag, the same galaxies which are believed to hosts SBHs. Stellar nuclei, on the other hand, are present in as many as 80% of low- and intermediate-luminosity galaxies. Remarkably, SBHs and stellar nuclei obey a similar "M-sigma" relation, and both contain the same mean fraction, ~0.2%, of the total galactic mass. I will argue that the creation of a "central massive object" (CMO) is a generic by-product of galaxy formation, with SBHs and stellar nuclei being the dominant modes of CMO formation in bright and intermediate/faint galaxies respectively.
Special ACKS Seminar: Dragan Huterer