1996/05/20 by U. Lisenfeld, Lisenfeld, U., H. J. Voelk +3
Physics and Astronomy · #Astrophysics (astro-ph) #FOS: Physical sciences #astro-ph
paper · pdf · doi:10.48550/arxiv.astro-ph/9605118
9 pages A&A tex, 10 postscript figures, accepted for publication in Astronomy & Astrophysics
arxiv created 1996/05/20 · arxiv updated 2009/12/01
This paper presents an analysis of the correlation between the far-infrared (FIR) and the radio emission of starburst galaxies. Data for interacting galaxies, many of which are undergoing a starburst, and for normal galaxies have been analysed and compared in order to test for any influence of the star-formation activity on the ratio between the FIR and the radio emission at 2.4 GHz, \q24. No statistically significant indication for such an influence has been found: There is neither a significant difference between \q24 of the two samples nor a dependence of this ratio on the starburst strength. This observational fact is unexpected because of the different physical conditions and the short time-scale of the star-formation activity in a starburst. In order to interprete the observations the FIR and the radio emission during a starburst have been modeled. The following conclusions could be drawn from the observed constancy of \q24: A strong and fast (≈ 107 yr) increase of the magnetic field at the beginning of the starburst is required in order to maintain a constant \q24. Otherwise the strong Inverse Compton losses that are due to the intense radiation field in a starburst would lower the synchrotron emission drastically resulting in a value of \q24 significantly higher than the observed one. Furthermore, the time-scale of the variation of the star-formation rate has to be longer than some 107 yr. For lower values the different time-scales of the FIR and the radio emission produce large fluctuations of \q24.