2018/09/30 by Elisa Boera, George D. Becker, James S. Bolton +1 · 1 citation
Physics and Astronomy · #astro-ph.CO
paper · pdf · doi:10.3847/1538-4357/aafee4
36 pages, 35 figures, replaced with the accepted version (ApJ); 2 additional sections in the Appendix, updated references
arxiv created 2019/01/31 · arxiv updated 2019/02/27
We present a new investigation of the thermal history of the intergalactic medium (IGM) during and after reionization using the Lyman-α forest flux power spectrum at 4.0\lesssim z\lesssim5.2. Using a sample of 15 high-resolution spectra, we measure the flux power down to the smallest scales ever probed at these redshifts (-1\lesssim log(k/km-1s)\lesssim -0.7). These scales are highly sensitive to both the instantaneous temperature of the IGM and the total energy injected per unit mass during and after reionization. We measure temperatures at the mean density of T0∼7000-8000 K, consistent with no significant temperature evolution for redshifts 4.2\lesssim z\lesssim5.0. We also present the first observational constraints on the integrated IGM thermal history, finding that the total energy input per unit mass increases from u0∼4.6 \rm eV m\rm p-1 to 7.3 eV m\rm p-1 from z∼ 6 to 4.2 assuming a Λ-CDM cosmology. We show how these results can be used simultaneously to obtain information on the timing and the sources of the reionization process. Our first proof of concept using simplistic models of instantaneous reionization produces results comparable to and consistent with the recent Planck constraints, favoring models with z\rm rei∼ 8.5+1.1-0.8.