MNRAS-2014-Dixon-987-1001.pdf (1.66 MB)
Semi-numeric simulations of helium reionization and the fluctuating radiation background
journal contribution
posted on 2023-06-08, 17:55 authored by Keri DixonKeri Dixon, Steven R Furnaletto, Andrei MesingerRecent He II Lyman-alpha forest observations from 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 halos, ionization state of helium, and density field at z = 3 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 He II ionization 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.
Funding
Astronomy rolling grant; G0278; STFC-SCIENCE AND TECHNOLOGY FACILITIES COUNCIL; ST/I000976/1
History
Publication status
- Published
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- Published version
Journal
Monthly Notices of the Royal Astronomical SocietyISSN
0035-8711Publisher
Wiley-BlackwellExternal DOI
Volume
440Page range
987-1001Department affiliated with
- Physics and Astronomy Publications
Full text available
- Yes
Peer reviewed?
- Yes
Legacy Posted Date
2014-07-24First Open Access (FOA) Date
2014-07-24First Compliant Deposit (FCD) Date
2014-07-24Usage metrics
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