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From optical spectroscopy of X-ray sources observed as part of ChaMP, wepresent redshifts and classifications for a total of 1569 Chandra sources fromour targeted spectroscopic follow up using the FLWO, SAAO, WIYN, CTIO, KPNO,Magellan, MMT and Gemini telescopes, and from archival SDSS spectroscopy. Weclassify the optical counterparts as 50% BLAGN, 16% NELG, 14% ALG, and 20%stars. We detect QSOs out to z~5.5 and galaxies out to z~3. We have compiledextensive photometry from X-ray to radio bands. Together with our spectroscopicinformation, this enables us to derive detailed SEDs for our extragalacticsources. We fit a variety of templates to determine bolometric luminosities,and to constrain AGN and starburst components where both are present. While~58% of X-ray Seyferts require a starburst event to fit observed photometryonly 26% of the X-ray QSO population appear to have some kind of star formationcontribution. This is significantly lower than for the Seyferts, especially ifwe take into account torus contamination at z>1 where the majority of our X-rayQSOs lie. In addition, we observe a rapid drop of the percentage of starburstcontribution as X-ray luminosity increases. This is consistent with thequenching of star formation by powerful QSOs, as predicted by the merger model,or with a time lag between the peak of star formation and QSO activity. We havetested the hypothesis that there should be a strong connection between X-rayobscuration and star-formation but we do not find any association between X-raycolumn density and star formation rate both in the general population or thestar-forming X-ray Seyferts. Our large compilation also allows us to reporthere the identification of 81 XBONG, 78 z>3 X-ray sources and 8 Type-2 QSOcandidates. Also we have identified the highest redshift (z=5.4135) X-rayselected QSO with optical spectroscopy.

The Chandra Multi-Wavelength Project: Optical Spectroscopy and the Broadband Spectral Energy Distributions of X-ray Selected AGN