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Published September 2007 | Published
Journal Article Open

Magellan Spectroscopy of AGN Candidates in the COSMOS Field


We present spectroscopic redshifts for the first 466 X-ray- and radio-selected AGN targets in the 2 deg^2 COSMOS field. Spectra were obtained with the IMACS instrument on the Magellan (Baade) telescope, using the nod-and-shuffle technique. We identify a variety of type 1 and type 2 AGNs, as well as red galaxies with no emission lines. Our redshift yield is 72% down to i_(AB) = 24, although the yield is >90% for i_(AB) < 22. We expect the completeness to increase as the survey continues. When our survey is complete and additional redshifts from the zCOSMOS project are included, we anticipate ~1100 AGNs with redshifts over the entire COSMOS field. Our redshift survey is consistent with an obscured AGN population that peaks at z ~ 0.7, although further work is necessary to disentangle the selection effects.

Additional Information

© 2009 American Astronomical Society. Print publication: Issue 1 (2007 September); received 2006 April 24; accepted for publication 2006 May 26. We would like to thank Alan Dressler and the IMACS team for creating an excellent instrument, as well as telescope operators Hernan Nuñez and Felipe Sanchez and the Las Campanas Observatory staff for support while observing. We thank Mike Westover for help with the January observations.We also thank the COSMOS team for their work in creating the catalogs used for selecting our targets. The HST COSMOS Treasury program was supported through NASA grant HST-GO-09822.

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Published - TRUapjss07.pdf


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