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Published June 10, 2010 | Published
Journal Article Open

Radio Sources from a 31 GHz Sky Survey with the Sunyaev-Zel'dovich Array

Abstract

We present the first sample of 31 GHz selected sources to flux levels of 1 mJy. From late 2005 to mid-2007, the Sunyaev-Zel'dovich Array observed 7.7 deg^2 of the sky at 31 GHz to a median rms of 0.18 mJy beam^(-1). We identify 209 sources at greater than 5σ significance in the 31 GHz maps, ranging in flux from 0.7 mJy to ~200 mJy. Archival NVSS data at 1.4 GHz and observations at 5 GHz with the Very Large Array are used to characterize the sources. We determine the maximum-likelihood integrated source count to be N(>S) = (27.2 ± 2.5)deg^(–2) × (S_(mJy))^(–1.18±0.12) over the flux range 0.7-15 mJy. This result is significantly higher than predictions based on 1.4 GHz selected samples, a discrepancy which can be explained by a small shift in the spectral index distribution for faint 1.4 GHz sources. From comparison with previous measurements of sources within the central arcminute of massive clusters, we derive an overdensity of 6.8 ± 4.4, relative to field sources.

Additional Information

© 2010 American Astronomical Society. Received 2009 December 11; accepted 2010 April 6; published 2010 May 20. We thank John Cartwright, Ben Reddall, and Marcus Runyan for their significant contributions to the construction and commissioning of the SZA instrument. We thank the staff of the Owens Valley Radio Observatory and CARMA for their outstanding support. We thank Jonathan Sievers and Brian Mason for helpful discussions, Bryan Butler, Claire Chandler, Gustaaf van Moorsel, and Meri Stanley for their assistance with EVLA mosaicking observations, and Bryan Butler and Mark Gurwell for providing the Mars model to which the SZA data are calibrated. We gratefully acknowledge the James S. McDonnell Foundation, the National Science Foundation and the University of Chicago for funding to construct the SZA. The operation of the SZA is supported by NSF Division of Astronomical Sciences through grant AST-0604982. Partial support is provided by NSF Physics Frontier Center grant PHY-0114422 to the Kavli Institute of Cosmological Physics at the University of Chicago, and by NSF grants AST-0507545 and AST-05-07161 to Columbia University. A.M. acknowledges support from a Sloan Fellowship, and S.M. from an NSF Astronomy and Astrophysics Fellowship, and C.G., S.M., and M.S. from NSF Graduate Research Fellowships. Facilities: SZA, VLA

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August 22, 2023
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