CfA Colloquium Schedule Fall 2007
 1 November 2007

1 November 2007

Speaker: Paul Green (CfA)

Title: Black Holes in the Blue Yonder - the Chandra Multiwavelength Project (ChaMP)


Supermassive black holes (SMBH) had their Glory Days about 10 Gyr ago, when they shone in abundance as luminous quasars. That active population has been downsizing ever since, but along the way the SMBH seem to have played a fundamental role in galaxy growth. Understanding this evolution means finding the SMBH then and now, a tricky business indeed. Theoretical models of AGN growth and triggering involve galaxy mergers and copious gas accretion that may hide most AGN, especially in their adolescence. Spectral decomposition of the Cosmic X-ray Background concurs, suggesting that much of that emission arises from heavily obscured objects.

X-ray observations play a key role in unveiling AGN, because most extragalactic X-ray sources are active galactic nuclei (AGN), and vice versa. The ongoing Chandra Multiwavelength Project is a large, archival survey of serendipitous sources in the X-ray sky at high Galactic latitude. We describe ChaMP results on the X-ray luminosity function of quasars and nearby galaxies, and compare results from X-ray vs. optical galaxy cluster selection. These studies use our own deep NOAO imaging, and spectroscopy from SAO telescopes including FLWO1.5m/FAST, MMT and Magellan. We also describe the extended ChaMP, encompassing 323 Chandra fields with SDSS overlap, from which we constrain the spectral energy distributions of a thousand broad line AGN and outline other ongoing projects.

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