Inferring the IGM thermal history during reionization with the Lyman α forest power spectrum at redshiftz≃ 5

Nasir, Fahad; Bolton, James S.; Becker, George D.

Abstract

We use cosmological hydrodynamical simulations to assess the feasibility of constraining the thermal history of the intergalactic medium during reionisation with the Lyα forest at z ≃ 5. The integrated thermal history has a measureable impact on the transmitted flux power spectrum that can be isolated from Doppler broadening at this redshift. We parameterise this using the cumulative energy per proton, u₀, deposited into a gas parcel at the mean background density, a quantity that is tightly linked with the gas density power spectrum in the simulations. We construct mock observations of the line of sight Lyα forest power spectrum and use a Markov Chain Monte Carlo approach to recover u₀ at redshifts 5≲z≲12. A statistical uncertainty of ∼ 20 per cent is expected (at 68 per cent confidence) at z ≃ 5 using high resolution spectra with a total redshift path length of Δz = 4 and a typical signal-to-noise ratio of S/N = 15 per pixel. Estimates for the expected systematic uncertainties are comparable, such that existing data should enable a measurement of u₀ to within ∼ 30 per cent. This translates to distinguishing between reionisation scenarios with similar instantaneous temperatures at z ≃ 5, but with an energy deposited per proton that differs by 2–3eV over the redshift interval 5≲z≲12. For an initial temperature of T ∼ 10⁴K following reionisation, this corresponds to the difference between early (zre = 12) and late (zre = 7) reionisation in our models.

Citation

Nasir, F., Bolton, J. S., & Becker, G. D. (2016). Inferring the IGM thermal history during reionization with the Lyman α forest power spectrum at redshiftz≃ 5. Monthly Notices of the Royal Astronomical Society, 463(3), 2335-2347. https://doi.org/10.1093/mnras/stw2147

• Journal Article Type: Article
• Acceptance Date: Aug 23, 2016
• Online Publication Date: Aug 25, 2016
• Publication Date: Dec 11, 2016
• Deposit Date: Sep 22, 2016
• Publicly Available Date: Sep 22, 2016
• Journal: Monthly Notices of the Royal Astronomical Society
• Print ISSN: 0035-8711
• Electronic ISSN: 1365-2966
• Publisher: Oxford University Press
• Peer Reviewed: Peer Reviewed
• Volume: 463
• Issue: 3
• Pages: 2335-2347
• DOI: https://doi.org/10.1093/mnras/stw2147
• Keywords: Dark Ages, Reionization, First Stars - Methods: Numerical - Intergalactic Medium - Quasars: Absorption Lines
• Public URL: https://nottingham-repository.worktribe.com/output/804588
• Publisher URL: http://mnras.oxfordjournals.org/content/early/2016/08/25/mnras.stw2147
• Additional Information: This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society ©: 2016 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.
• Contract Date: Sep 22, 2016