2016/05/31 by Fahad Nasir, James S. Bolton, George D. Becker · 1 citation
Physics and Astronomy · #astro-ph.CO
paper · pdf · doi:10.1093/mnras/stw2147
14 pages, 8 figures, 2 Tables, Accepted for publication in MNRAS
arxiv created 2016/08/23 · arxiv updated 2016/08/31
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 \rm 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 2-3 \rm eV over the redshift interval 5≤ z ≤ 12. For an initial temperature of T∼ 104\rm K following reionisation, this corresponds to the difference between early (z\rm re=12) and late (z\rm re=7) reionisation in our models.