A closer look at using quasar near-zones as a probe of neutral hydrogen in the intergalactic medium

S. Bolton, James; G. Haehnelt, Martin

Abstract

We examine a large set of synthetic quasar spectra to realistically assess the potential of using the relative sizes of highly ionized near-zones in the Lya and Lyb forest as a probe of the neutral hydrogen content of the intergalactic medium (IGM) at z>6. The scatter in the relative near-zone size distribution, induced by underlying fluctuations in the baryonic density field and the filtering of ionizing radiation, is considerable even for fixed assumptions about the IGM neutral fraction. As a consequence, the current observational data cannot distinguish between an IGM which is significantly neutral or highly ionized just above z=6. Under standard assumptions for quasar ages and ionizing luminosities, a future sample of several tens of high resolution Lya and Lyb near-zone spectra should be capable of distinguishing between a volume weighted neutral hydrogen fraction in the IGM which is greater or less than 10 per cent.

• Journal Article Type: Article
• Acceptance Date: Jul 5, 2007
• Publication Date: 2007-10
• Deposit Date: Sep 16, 2019
• Publisher: Oxford University Press
• Peer Reviewed: Peer Reviewed
• Volume: 381
• Issue: 1
• Pages: L35-L39
• DOI: https://doi.org/10.1111/j.1745-3933.2007.00361.x
• Keywords: Astrophysics
• Public URL: https://nottingham-repository.worktribe.com/output/2462358
• Publisher URL: https://onlinelibrary.wiley.com/doi/10.1111/j.1745-3933.2007.00361.x