The Radio-Infrared Correlation within Galaxies
A comparison of the distributions of 60μm infrared and 20cm radio continuum emission within spiral galaxies reveals a broad correlation between the two, which is modulated by a slow decrease in the 60μm-to-20cm ratio with increasing radius. Using these results, we propose a physical model for understanding the tight correlation between far-infrared and non-thermal radio luminosities in star-forming galaxies. This approach suggests that the basic constraint implied by the correlation is a tight coupling between the sources of the dust-heating photons and those of cosmic-ray electrons. Among spiral galaxies, we require in addition a universal relation whereby magnetic field strength scales with gas density to a power l/3≤β≤2/3.
KeywordsStar Formation Spiral Galaxy Tight Coupling Disk Galaxy Star Formation Activity
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