CfA Colloquium Schedule Spring 2005
 24 February 2005

24 February 2005

Speaker: Luis Ho (Carnegie Observatories)

Title: Black Hole Demographics in the Local Universe

Abstract: A significant fraction of local galaxies show evidence of nuclear activity. I argue that the bulk of this activity, while energetically not remarkable, derives from accretion onto a central massive black hole. The statistics of nearby active galactic nuclei thus provide an effective probe of black hole demography. Consistent with the picture emerging from direct dynamical studies, the local census of nuclear activity strongly suggests that most, perhaps all, galaxies with a significant bulge component contain a central massive black hole. Although late-type galaxies appear to be generally deficient in nuclear black holes, there are important exceptions to this rule. I highlight recent developments in the search for "intermediate-mass" (10^4-10^6 solar mass) black holes in late-type galaxies, and their implications for seeding the formation of supermassive black holes and the detection of gravitational waves.

Video of the Presentation (Talks can be viewed with RealPlayer. Free download is available from )

References for students:

  1. Black Hole Demography from Nearby Active Galactic Nuclei,
  2. Low-state Black Hole Accretion in Nearby Galaxies, see preprints in


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