The FIR/radio correlation in starburst galaxies - constraints on starburst models

U. Lisenfeld; H. J. Voelk; C. Xu

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arXiv · astro-ph/9605118

The FIR/radio correlation in starburst galaxies - constraints on starburst models

U. Lisenfeld·H. J. Voelk·C. Xu

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Abstract

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 ($\approx 10^7$ 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 $10^7$ yr. For lower values the different time-scales of the FIR and the radio emission produce large fluctuations of $\q24$.

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U. Lisenfeld, H. J. Voelk, C. Xu. 1996-05-20. The FIR/radio correlation in starburst galaxies - constraints on starburst models. https://arxiv.org/abs/astro-ph/9605118

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