Abstract
While stars are widely discussed as the source of the high-energy
photons that reionized the universe, an additional source of ionizing
photons that must also contribute to reionization in this scenario are
the supernovae (SNe) which mark the end of the life of massive stars.
Here we estimate the relative contributions of SNe and stars to
reionization. While the rate at which ionizing photons are produced in
SNe shocks is well below that at which they are produced by stars, the
harder spectra of radiation emitted from SNe lead to an enhanced escape
fraction of SN-generated photons relative to that of stellar photons. In
particular, along a given line of sight out of a galaxy, we find that
for neutral hydrogen column densities N H >~
1018 cm-2 the contribution to reionization from
SNe is greater than that from stars. Drawing on the results of
simulations presented in the literature, we find that the overall
(line-of-sight-averaged) SNe shock-generated ionizing photon escape
fraction is larger than the stellar photon escape fraction by a factor
of sime4 to sime7, depending on the metallicity of the stellar
population. Overall, our results suggest that the effect of SNe is an
enhancement of up to ~10% in the fraction of hydrogen reionized by
stellar sources. We briefly discuss the implications of our results for
the population of galaxies responsible for reionization.
| Original language | English |
|---|---|
| Pages (from-to) | 126 |
| Journal | Astrophysical Journal |
| Volume | 743 |
| Publication status | Published - 1 Dec 2011 |
Keywords / Materials (for Non-textual outputs)
- cosmology: theory
- dark ages
- reionization
- first stars
- radiative transfer
- supernovae: general