HEAD 2003 Meeting
Session 37. Cosmic X-ray Background and Deep Surveys II
Oral, Tuesday, March 25, 2003, 9:00-10:00am

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[37.01] Characterizing the X-ray emitting populations which dominate the Cosmic X-ray Background.

J. Silverman (SAO), P. Green, B. Wilkes (CXC), P. Smith (Steward), ChaMP Collaboration

The Chandra Multiwavelength Project (ChaMP) is carrying out an extensive optical spectroscopic observing campaign to identify counterparts to Chandra X-ray sources. Since sources with 2-8 keV flux levels around 10-14 erg cm-2 s-1 dominate the CXRB, somewhat brighter than previously thought, the ChaMP survey is providing the demographics of the X-ray emitting population. We are acquiring spectra of 90% of the sources in a subset (22) of the ChaMP fields to an optical flux limit (r'<21). In addition, half of these fields will have the same high level of completeness to r'=22 to include the high redshift and possibly obscured AGN. We have amassed about 400 spectra using the WIYN/3.5m, CTIO/4m, KPNO/4m, Magellan, MMT and FLWO 1.5m. The sample primarily includes broad emission line AGN (65%, z<4) with significant subsets of narrow emission line galaxies (14%, z<1), absorption line galaxies (12%, z<1), 8% stars and 1% clusters. This sample will be used to measure the AGN X-ray Luminosity Function and to answer such questions as "Are we seeing the beginning of the quasar epoch at z>3 or does the onset of accretion occur at higher redshifts in contrast to optically selected samples?" We summarize the initial results of the spectroscopic study and highlight interesting/unusual sources found so far.

We gratefully acknowledge the financial support of NASA grant: AR1-2003X (Chandra).

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Bulletin of the American Astronomical Society, 35#2
© 2003. The American Astronomical Soceity.