Complex Radio Spectral Energy Distributions in Luminous and Ultraluminous Infrared Galaxies
Creators
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1.
National Radio Astronomy Observatory
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2.
University of Virginia
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3.
Carnegie Observatories
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4.
California Institute of Technology
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5.
New Mexico Institute of Mining and Technology
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6.
Max Planck Institute for Astronomy
Abstract
We use the Expanded Very Large Array to image radio continuum emission from local luminous and ultraluminous infrared galaxies (LIRGs and ULIRGs) in 1 GHz windows centered at 4.7, 7.2, 29, and 36 GHz. This allows us to probe the integrated radio spectral energy distribution (SED) of the most energetic galaxies in the local universe. The 4-8 GHz flux densities agree well with previous measurements. They yield spectral indices α ≈ –0.67 (where F_ν α ν^α) with ±0.15 (1σ) scatter, typical of nonthermal (synchrotron) emission from star-forming galaxies. The contrast of our 4-8 GHz data with literature 1.5 and 8.4 GHz flux densities gives further evidence for curvature of the radio SED of U/LIRGs. The SED appears flatter near ~1 GHz than near ~6 GHz, suggesting significant optical depth effects at lower frequencies. The high-frequency (28-37 GHz) flux densities are low compared to extrapolations from the 4-8 GHz data. We confirm and extend to higher frequency a previously observed deficit of high-frequency radio emission for luminous starburst galaxies.
Additional Information
© 2011 The American Astronomical Society. Received 2011 April 15; accepted 2011 June 21; published 2011 August 29. We thank the anonymous referee for suggestions that improved this work. The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc. Support for A.K.L. during part of this work was provided by NASA through Hubble Fellowship grantHST-HF-51258.01-A awarded by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., for NASA, under contract NAS 5-26555.Attached Files
Published - Leroy2011p15918Astrophys_J_Lett.pdf
Files
Leroy2011p15918Astrophys_J_Lett.pdf
Additional details
Identifiers
- Eprint ID
- 25484
- Resolver ID
- CaltechAUTHORS:20110929-091829109
Funding
- NASA Hubble Fellowship
- HST-HF-51258.01-A
- NASA
- NAS 5-26555
- Space Telescope Science Institute
Dates
- Created
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2011-09-29Created from EPrint's datestamp field
- Updated
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2021-11-09Created from EPrint's last_modified field
Caltech Custom Metadata
- Caltech groups
- Infrared Processing and Analysis Center (IPAC) , Physics Department