Repository logo
 

Spatial fluctuations of the intergalactic temperature-density relation after hydrogen reionization

Published version
Peer-reviewed

Type

Article

Change log

Authors

Keating, Laura C 
Puchwein, Ewald 
Haehnelt, Martin G 

Abstract

The thermal state of the post-reionization IGM is sensitive to the timing of reionization and the nature of the ionizing sources. We have modelled here the thermal state of the IGM in cosmological radiative transfer simulations of a realistic, extended, spatially inhomogeneous hydrogen reionization process, carefully calibrated with Ly α forest data. We compare these with cosmological simulations run using a spatially homogeneous ionizing background. The simulations with a realistic growth of ionized regions and a realistic spread in reionization redshifts show, as expected, significant spatial fluctuations in the temperature–density relation (TDR) of the post-reionization IGM. The most recently ionized regions are hottest and exhibit a flatter TDR. In simulations consistent with the average TDR inferred from Ly α forest data, these spatial fluctuations have a moderate but noticeable effect on the statistical properties of the Ly α opacity of the IGM at z ∼ 4–6. This should be taken into account in accurate measurements of the thermal properties of the IGM and the free-streaming of dark matter from Ly α forest data in this redshift range. The spatial variations of the TDR predicted by our simulations are, however, smaller by about a factor of 2 than would be necessary to explain the observed large spatial opacity fluctuations on large (≥50 h−1 comoving Mpc) scales atz ≳ 5.5.

Description

Keywords

methods: numerical, galaxies: high-redshift, intergalactic medium, quasars: absorption lines, dark ages, reionization, first stars

Journal Title

Monthly Notices of the Royal Astronomical Society

Conference Name

Journal ISSN

0035-8711
1365-2966

Volume Title

477

Publisher

Oxford University Press
Sponsorship
European Research Council (320596)
Science and Technology Facilities Council (ST/H008861/1)
Science and Technology Facilities Council (ST/K001590/1)
Science and Technology Facilities Council (ST/K00333X/1)
Science and Technology Facilities Council (ST/P000673/1)
Science and Technology Facilities Council (ST/L000636/1)
Science and Technology Facilities Council (ST/N000927/1)
LCK acknowledges the support of a CITA postdoctoral fellowship, an Isaac Newton studentship, the Cambridge Trust, and STFC. Support by the FP7 ERC Advanced Grant Emergence-320596 is gratefully acknowledged. EP acknowledges support from the Kavli Foundation. This work used the DiRAC Data Analytic system at the University of Cambridge, operated by the University of Cambridge High Performance Computing Service on behalf of the STFC DiRAC HPC Facility (www.dirac.ac.uk). This equipment was funded by BIS National E-infrastructure capital grant (ST/K001590/1), STFC capital grants ST/H008861/1 and ST/H00887X/1, and STFC DiRAC Operations grant ST/K00333X/1. DiRAC is part of the National E-Infrastructure. This research was supported by the Munich Institute for Astro- and Particle Physics (MIAPP) of the DFG cluster of excellence ‘Origin and Structure of the Universe’.