Volume 460, Number 1, December II 2006
|Page(s)||67 - 81|
|Published online||12 September 2006|
Time evolution of the radio continuum of young starbursts: the importance of synchrotron emission
Center for Computational Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8577, Japan e-mail: firstname.lastname@example.org
2 INAF – Istituto di Radioastronomia-Sezione Firenze, Largo E. Fermi 5, 50125 Firenze, Italy e-mail: email@example.com
Accepted: 30 August 2006
We investigate the radio spectral energy distributions (SEDs) of young star-forming galaxies and how they evolve with time. The duration and luminosity of the nonthermal radio emission from supernova remnants (SNRs) are constrained by using the observational radio SEDs of SBS 0335-052 and I Zw 18, which are the two lowest-metallicity blue compact dwarf galaxies in the nearby universe. The typical radio “fluence” for SNRs in SBS 0335-052, that is the radio energy emitted per SNR over its radiative lifetime, is estimated to be ~6– at 5 GHz. On the other hand, the radio fluence in I Zw 18 is ~1– at 5 GHz. We discuss the origin of this variation and propose scaling relations between synchrotron luminosity and gas density. We have also predicted the time dependence of the radio spectral index and of the spectrum itself, for both the “active” (SBS 0335-052) and “passive” (I Zw 18) cases. These models enable us to roughly age date and classify radio spectra of star-forming galaxies into active/passive classes. Implications for high-z galaxy evolution are also discussed.
Key words: galaxies: dwarf / galaxies: evolution / galaxies: ISM / ISM: supernova remnants / radio continuum: galaxies
© ESO, 2006
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.