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Searching for new OH megamasers out to redshifts z>1

Published online by Cambridge University Press:  24 July 2012

Kyle W. Willett
Kyle W. Willett*
Affiliation:
Center for Astrophysics and Space Astronomy, University of ColoradoUCB 391, Boulder, CO 80304, United States School of Physics and Astronomy, University of Minnesota116 Church St. SE, Minneapolis, MN 55455, United States email: willett@physics.umn.edu
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Abstract

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We have carried out a search for 18-cm OH megamaser (OHM) emission with the Green Bank Telescope. The targeted galaxies comprise a sample of 121 ULIRGs at 0.09<z<1.5, making this is the first large, systematic search for OHMs at z>0.25. Nine new detections of OHMs are reported, all at redshifts z<0.25. For the remainder of the galaxies, observations constrain the upper limit on OH emission; this rules out OHMs of moderate brightness (LOH>103 L⊙) for 26% of the sample, and extremely bright OHM emission (LOH>104 L⊙) for 73% of the sample. Losses from RFI result in the OHM detection fraction being significantly lower than expected for galaxies with LIR>1012 L⊙. The new OHM detections are used to calculate an updated OH luminosity function, with Φ∝ LOH−0.66; this slope is in agreement with previous results. Non-detections of OHMs in the COSMOS field constrain the predicted sky density of OHMs; the results are consistent with a galaxy merger rate evolving as (1+z)m, where m≤6.

Keywords

masersradio lines: galaxiesinfrared: galaxiesgalaxies: interactions
Type
Contributed Papers
Information
Proceedings of the International Astronomical Union , Volume 8 , Symposium S287: Cosmic Masers - from OH to H0 , January 2012 , pp. 345 - 349
Copyright
Copyright © International Astronomical Union 2012

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