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Complex Radio Spectral Energy Distributions in Luminous and Ultraluminous Infrared Galaxies

Leroy, Adam K. and Evans, Aaron S. and Momjian, Emmanuel and Murphy, Eric and Ott, Jürgen and Armus, Lee and Condon, James and Haan, Sebastian and Mazzarella, Joseph M. and Meier, David S. and Privon, George C. and Schinnerer, Eva and Surace, Jason and Walter, Fabian (2011) Complex Radio Spectral Energy Distributions in Luminous and Ultraluminous Infrared Galaxies. Astrophysical Journal Letters, 739 (1). Art. No. L25. ISSN 2041-8205.

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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.

Item Type:Article
Related URLs:
URLURL TypeDescription
Leroy, Adam K.0000-0002-2545-1700
Evans, Aaron S.0000-0003-2638-1334
Momjian, Emmanuel0000-0003-3168-5922
Murphy, Eric0000-0001-7089-7325
Ott, Jürgen0000-0001-8224-1956
Armus, Lee0000-0003-3498-2973
Condon, James0000-0003-4724-1939
Mazzarella, Joseph M.0000-0002-8204-8619
Meier, David S.0000-0001-9436-9471
Privon, George C.0000-0003-3474-1125
Schinnerer, Eva0000-0002-3933-7677
Surace, Jason0000-0001-7291-0087
Walter, Fabian0000-0003-4793-7880
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.
Group:Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
NASA Hubble FellowshipHST-HF-51258.01-A
NASANAS 5-26555
Space Telescope Science InstituteUNSPECIFIED
Subject Keywords:galaxies: active; galaxies: starburst; infrared: galaxies; radio continuum: galaxies
Issue or Number:1
Classification Code:PACS: 98.62.Ai; 98.70.Lt; 98.70.Dk; 98.54.Ep
Record Number:CaltechAUTHORS:20110929-091829109
Persistent URL:
Official Citation:Complex Radio Spectral Energy Distributions in Luminous and Ultraluminous Infrared Galaxies Adam K. Leroy et al. 2011 ApJ 739 L25
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:25484
Deposited By: Ruth Sustaita
Deposited On:29 Sep 2011 17:01
Last Modified:09 Mar 2020 13:18

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