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Published October 1, 2007 | Published
Journal Article Open

The FIRST-2MASS Red Quasar Survey

Abstract

Combining radio observations with optical and infrared color selection, demonstrated in our pilot study to be an efficient selection algorithm for finding red quasars, we have obtained optical and infrared spectroscopy for 120 objects in a complete sample of 156 candidates from a sky area of 2716 deg^2. Consistent with our initial results, we find that our selection criteria (J - K > 1.7, R - K > 4.0) yield a ~50% success rate for discovering quasars substantially redder than those found in optical surveys. Comparison with UVX- and optical color-selected samples shows that ≳ 10% of the quasars are missed in a magnitude-limited survey. Simultaneous two-frequency radio observations for part of the sample indicate that a synchrotron continuum component is ruled out as a significant contributor to reddening the quasars' spectra. We go on to estimate extinctions for our objects assuming that their red colors are caused by dust. Continuum fits and Balmer decrements suggest E(B - V) values ranging from near zero to 2.5 mag. Correcting the K-band magnitudes for these extinctions, we find that for K ≤ 14.0, red quasars make up between 25% and 60% of the underlying quasar population; owing to the incompleteness of 2MASS at fainter K-band magnitudes, we can only set a lower limit to the radio-detected red quasar population of >20%-30%.

Additional Information

© 2007 The American Astronomical Society. Received 2007 March 6; accepted 2007 June 20. We thank Sally Laurent-Muehleisen for assisting with the VLA observations and Johnny Metelsky for reducing and analyzing them. The work of E. G. and D. J. H. was supported at Columbia by the National Science Foundation (NSF) under grant AST 05- 07598. The work of R. H. B. and M. D. G. was also supported in part under the auspices of the US Department of Energy by Lawrence Livermore National Laboratory under contract W-7405-ENG-48. This publication makes use of data products from the Two Micron All Sky Survey, which is a joint project of the University of Massachusetts and the Infrared Processing and Analysis Center/California Institute of Technology, funded by the National Aeronautics and Space Administration and the NSF. Funding for the creation and distribution of the SDSS Archive has been provided by the Alfred P. Sloan Foundation, the Participating Institutions, the National Aeronautics and Space Administration, the NSF, the US Department of Energy, the Japanese Monbukagakusho, and the Max-Planck Society. The SDSS Web site is http://www.sdss.org. The SDSS is managed by the Astrophysical Research Consortium( ARC) for the Participating Institutions. The Participating Institutions are the University of Chicago, Fermilab, the Institute for Advanced Study, the Japan Participation Group, Johns Hopkin sUniversity, the Korean Scientist Group, Los Alamos National Laboratory, the Max-Planck-Institute for Astronomy (MPIA), the Max-Planck-Institute for Astrophysics (MPA),New Mexico State University, University of Pittsburgh, University of Portsmouth, Princeton University, the United States Naval Observatory, and the University of Washington. The Guide Star Catalogue II is a joint project of the Space Telescope Science Institute and the Osservatorio Astronomico di Torino. Space Telescope Science Institute is operated by the Association of Universities for Research in Astronomy, for the National Aeronautics and Space Administration under contract NAS5-26555. The participation of the Osservatorio Astronomico di Torino is supported by the Italian Council for Research in Astronomy. Additional support is provided by European Southern Observatory, Space Telescope European Coordinating Facility, the International GEMINI project, and the European Space Agency Astrophysics Division. TIFKAM was funded by Ohio State University, the MDM consortium, MIT, and NSF grant AST 96-05012. NOAO and USNO paid for the development of the ALADDIN arrays and contributed the array currently in use in TIFKAM.

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August 22, 2023
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