Relating Diffusion Properties of Cosmic-Ray Electrons to Star Formation Activity within Normal Galaxies
Abstract
Using data obtained as part of the {\it Spitzer} Infrared Nearby Galaxies Survey (SINGS; Kennicutt et al. 2003) and WSRT-SINGS radio continuum survey (Braun et al. 2006), we study the effects of star-formation activity on the far-infrared (FIR)--radio correlation {\it within} galaxies. This is done by testing a phenomenological model for the correlation, which describes the radio image as a smeared version of the FIR image. We find that this description works particularly well for galaxies with higher infrared surface brightnesses, yielding best-fit smoothing scale-lengths of a few hundred parsecs, substantially shorter than those for lower surface brightness galaxies. We interpret this result to suggest that galaxies with higher disk averaged star formation rates have had a recent episode of enhanced star formation and are characterized by a higher fraction of young cosmic-ray (CR) electrons compared to galaxies with lower star formation activity.
Cite
@article{arxiv.astro-ph/0609038,
title = {Relating Diffusion Properties of Cosmic-Ray Electrons to Star Formation Activity within Normal Galaxies},
author = {E. J. Murphy and G. Helou and L. Armus and R. Braun and J. D. P. Kenney and the SINGS team},
journal= {arXiv preprint arXiv:astro-ph/0609038},
year = {2007}
}
Comments
2 pages, 1 figure; To appear in "Studying Galaxy Evolution with Spitzer and Herschel", conference held in Crete, Greece, May 2006. CUP conference series eds. V.Charmandaris, D.Rigopoulou, and N.D. Kylafis