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Date and Time of the Query: 2019-06-16 T22:02:56 PDT
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For refcode 1995ApJ...445..599M:
Retrieve 25 NED objects in this reference.
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Copyright by American Astronomical Society. Reproduced by permission
1995ApJ...445..599M THE SPATIAL VARIATION OF THE INFRARED-TO-RADIO RATIO IN SPIRAL GALAXIES K. A. MARSH Jet Propulsion Laboratory, California Institute of Technology, MS 306-451, 4800 Oak Grove Drive, Pasadena, CA 91109 AND G. HELOU Infrared Processing and Analysis Center, California Institute of Technology, IPAC 100-22, Pasadena, CA 91125 Received 1994 September 20; accepted 1994 December 12 ABSTRACT We have produced two-dimensional maps of the intensity ratio, Q_60_, of 60 microns infrared to 20 cm radio continuum emission, for a set of 25 nearby galaxies, mostly spirals. The ratio maps were obtained from infrared images made using IRAS data with the maximum correlation method, and radio images made using VLA data. Before taking the ratio, the radio images were processed so as to have the same resolution properties as the infrared images; the final spatial resolution in all cases is approximately 1', corresponding to 1-2 kpc for most galaxies. This resolution represents a significant improvement over previous studies. Our new high-resolution maps confirm the slow decrease of Q_60_ with increasing radial distance from the nucleus, but show additional structure which is probably associated with separate sites of active star formation in the spiral arms. The maps show Q_60_ to be more closely related to infrared surface brightness than to the radial distance r in the galaxy disk. We note also that the Q_60_ gradients are absent (or at least reduced) for the edge-on galaxies, a property which can be attributed to the dilution of contrast due to the averaging of the additional structure along the line of sight. The results are all in qualitative agreement with the suggestion that the radio image represents a smeared version of the infrared image, as would be expected on the basis of current models in which the infrared- radio correlation is driven by the formation of massive stars, and the intensity distribution of radio emission is smeared as a result of the propagation of energetic electrons accelerated during the supernova phase. Subject headings: galaxies: photometry - galaxies: spiral - infrared: galaxies - radio continuum: galaxies
Retrieve 25 NED objects in this reference.
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