Skip to main content
Open Access Publications from the University of California

Semi-numeric simulations of helium reionization and the fluctuating radiation background

  • Author(s): Dixon, KL
  • Furlanetto, SR
  • Mesinger, A
  • et al.

Recent He II Lyman a forest observations within the range 2.0 ≤ z ≤ 3.2 show large fluctuations in the optical depth at z ≥ 2.7. These results point to a fluctuating He-ionizing background, which may be due to the end of helium reionization of this era. We present a fast, semi-numeric procedure to approximate detailed cosmological simulations. We compute the distribution of dark matter haloes, ionization state of helium, and density field at z = 3, which are in broad agreement with recent simulations. Given our speed and flexibility, we investigate a range of ionizing source and active quasar prescriptions. Spanning a large area of parameter space, we find order-of-magnitude fluctuations in the HeIIionization rate in the post-reionization regime. During reionization, the fluctuations are even stronger and develop a bimodal distribution, in contrast to semi-analytic models and the hydrogen equivalent. These distributions indicate a low-level ionizing background even at significant He II fractions. © 2014 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society.

Many UC-authored scholarly publications are freely available on this site because of the UC Academic Senate's Open Access Policy. Let us know how this access is important for you.

Main Content
Current View