AAS 205th Meeting, 9-13 January 2005
Session 167 Quasars and Blazars
Oral, Thursday, January 13, 2005, 2:00-3:30pm, Royal Palm 1-3

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[167.05] Dust-obscured quasars selected from Spitzer's First Look Survey

M. Lacy (Spitzer Science Center), G. Canalizo (University of California, Riverside), S. Rawlings (University of Oxford), A. Sajina (University of British Columbia), E.L. Gates (UCO/Lick Observatory), L. Storrie-Lombardi, L. Armus (Spitzer Science Center)

We have identified several dust-obscured quasars in the Spitzer First Look Survey region using a selection based on mid-infrared color. Our selection allows us to directly compare the number density of obscured quasars with those of unobscured quasars from the Sloan survey in the same region of sky. This has enabled a direct comparison of the number densities of unobscured, type-1, and obscured, type-2, quasars at a given luminosity for the first time. Optical spectroscopy shows that most of our candidates show the high ionization, narrow-line spectra expected of type-2 quasars. At the low to moderate quasar luminosities probed by our study, our results show that the number density of type-2 objects is comparable to that of type-1s. A composite spectrum of the host galaxies of the type-2s show evidence for recent star formation activity. We discuss these results in the context of other studies of the dust-obscured quasar population.

This work is based on observations made with the Spitzer Space Telescope, which is operated by the Jet Propulsion Laboratory, California Institute of Technology under NASA contract 1407. Support for this work was provided by NASA through an award issued by JPL/Caltech.

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© 2004. The American Astronomical Society.