ARCADE 2 OBSERVATIONS OF GALACTIC RADIO EMISSION
- Code 665, Goddard Space Flight Center, Greenbelt, MD 20771 (United States)
- Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109 (United States)
- Columbia Astrophysics Laboratory, 550W 120th Street, Mail Code 5247, New York, NY 10027-6902 (United States)
- Department of Physics, Broida Hall, Mail Code 9530, University of California, Santa Barbara, CA 93106 (United States)
- Kavli Institute for Particle Astrophysics and Cosmology, SLAC National Accelerator Laboratory, Menlo Park, CA 94025 (United States)
We use absolutely calibrated data from the ARCADE 2 flight in 2006 July to model Galactic emission at frequencies 3, 8, and 10 GHz. The spatial structure in the data is consistent with a superposition of free-free and synchrotron emission. Emission with spatial morphology traced by the Haslam 408 MHz survey has spectral index {beta}{sub synch} = -2.5 {+-} 0.1, with free-free emission contributing 0.10 {+-} 0.01 of the total Galactic plane emission in the lowest ARCADE 2 band at 3.15 GHz. We estimate the total Galactic emission toward the polar caps using either a simple plane-parallel model with csc |b| dependence or a model of high-latitude radio emission traced by the COBE/FIRAS map of C II emission. Both methods are consistent with a single power law over the frequency range 22 MHz to 10 GHz, with total Galactic emission toward the north polar cap T{sub Gal} = 10.12 {+-} 0.90 K and spectral index {beta} = -2.55 {+-} 0.03 at reference frequency 0.31 GHz. Emission associated with the plane-parallel structure accounts for only 30% of the observed high-latitude sky temperature, with the residual in either a Galactic halo or an isotropic extragalactic background. The well-calibrated ARCADE 2 maps provide a new test for spinning dust emission, based on the integrated intensity of emission from the Galactic plane instead of cross-correlations with the thermal dust spatial morphology. The Galactic plane intensity measured by ARCADE 2 is fainter than predicted by models without spinning dust and is consistent with spinning dust contributing 0.4 {+-} 0.1 of the Galactic plane emission at 23 GHz.
- OSTI ID:
- 21576704
- Journal Information:
- Astrophysical Journal, Vol. 734, Issue 1; Other Information: DOI: 10.1088/0004-637X/734/1/4; ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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