The history of star formation of starburst galaxies

In this paper, we use different luminosity ratios to trace the histories of star formation of two different kinds of starburst galaxies: HII galaxies and starburst nucleus galaxies (SBNGs). The mean star formation rates (SFRs) for these galaxies is comparable, and compatible with a near constant star formation over a few Gyr period. We have also found an interesting difference between the burst stellar population of the SBNGs and the HII galaxies: SBNGs have an excess of intermediate-mass stars as compared to HII galaxies. We interpreted this difference as a sign that SBNGs have experienced a higher frequency of bursts of star formation than the HII galaxies. This interpretation is qualitatively consistent with the Stochastic Self Propagation of Star Formation (SSPSF) theory, which suggests that the starburst phenomenon depends on internal processes, regulated by the evolution of massive stars.