Imprints of temperature fluctuations on the z ∼ 5 Lyman-α forest: a view from radiation-hydrodynamic simulations of reionization
Abstract

Reionization leads to large spatial fluctuations in the intergalactic temperature that can persist well after its completion. We study the imprints of such fluctuations on the $z$ ∼ 5 Ly α forest flux power spectrum using a set of radiation-hydrodynamic simulations that model different reionization scenarios. We find that large-scale coherent temperature fluctuations bring ${\sim}20\text{--}60{{\ \rm per\ cent}}$ extra power at k ∼ 0.002 s km−1, with the largest enhancements in the models where reionization is extended or ends the latest. On smaller scales (k ≳ 0.1 s km−1), we find that temperature fluctuations suppress power by ${\lesssim}10{{\ \rm per\ cent}}$. We find that the shape of the power spectrum is mostly sensitive to the reionization mid-point rather than temperature fluctuations from reionization’s patchiness. However, for all of our models with reionization mid-points of $z$ ≤ 8 ($z$ ≤ 12), the shape differences are ${\lesssim}20{{\ \rm per\ cent}}$ (${\lesssim}40{{\ \rm per\ cent}}$) because of a surprisingly well-matched cancellation between thermal broadening and pressure smoothing that occurs for realistic thermal histories. We also consider fluctuations in the ultraviolet background, finding their impact on the power spectrum to be much smaller than temperature fluctuations at k ≳ 0.01 s km−1. Furthermore, we compare our models to power spectrum more »

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Award ID(s):
Publication Date:
NSF-PAR ID:
10122684
Journal Name:
Monthly Notices of the Royal Astronomical Society
Volume:
490
Issue:
3
Page Range or eLocation-ID:
p. 3177-3195
ISSN:
0035-8711
Publisher:
Oxford University Press
1. ABSTRACT Using a set of high resolution simulations, we quantify the effect of species-specific initial transfer functions on probes of the intergalactic medium (IGM) via the Lyman-α forest. We focus on redshifts 2–6, after H i reionization. We explore the effect of these initial conditions on measures of the thermal state of the low density IGM: the curvature, Doppler width cutoff, and Doppler width distribution. We also examine the matter and flux power spectrum, and potential consequences for constraints on warm dark matter models. We find that the curvature statistic is at most affected at the $\approx 2{{\ \rm per\ cent}}$more »