The Kinetic Sunyaev-Zel'dovich effect as a probe of the physics of cosmic reionization: the effect of self-regulated reionization

Park, Hyunbae, Shapiro, Paul R, Komatsu, Eiichiro, Iliev, Ilian T, Ahn, Kyungjin and Mellema, Garrelt (2013) The Kinetic Sunyaev-Zel'dovich effect as a probe of the physics of cosmic reionization: the effect of self-regulated reionization. Astrophysical Journal, 769 (2). p. 93. ISSN 0004-637X

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We calculate the angular power spectrum of the Cosmic Microwave Background
(CMB) temperature fluctuations induced by the kinetic Sunyaev-Zel'dovich (kSZ)
effect from the epoch of reionization (EOR). We use detailed N-body+radiative
transfer simulations to follow inhomogeneous reionization of the intergalactic
medium (IGM). For the first time we take into account the "self-regulation" of
reionization: star formation in low-mass dwarf galaxies (10^8 M_\sun \lesssim M
\lesssim 10^9 M_\sun) or minihalos (10^5 M_\sun \lesssim M \lesssim 10^8
M_\sun) is suppressed if these halos form in the regions that were already
ionized or Lyman-Werner dissociated. Some previous work suggested that the
amplitude of the kSZ power spectrum from the EOR can be described by a
two-parameter family: the epoch of half ionization and the duration of
reionization. However, we argue that this picture applies only to simple forms
of the reionization history which are roughly symmetric about the
half-ionization epoch. In self-regulated reionization, the universe begins to
be ionized early, maintains a low level of ionization for an extended period,
and then finishes reionization as soon as high-mass atomically-cooling halos
dominate. While inclusion of self-regulation affects the amplitude of the kSZ
power spectrum only modestly (\sim 10 %), it can change the duration of
reionization by a factor of more than two. We conclude that the simple
two-parameter family does not capture the effect of a physical, yet complex,
reionization history caused by self-regulation. When added to the
post-reionization kSZ contribution, our prediction for the total kSZ power
spectrum is below the current upper bound from the South Pole Telescope.
Therefore, the current upper bound on the kSZ effect from the EOR is consistent
with our understanding of the physics of reionization.

Item Type: Article
Keywords: cosmic background radiation, dark ages, reionization, first stars, early universe, galaxies: high-redshift, intergalactic medium, large-scale structure of universe, radiative transfer
Schools and Departments: School of Mathematical and Physical Sciences > Physics and Astronomy
Subjects: Q Science > QB Astronomy
Depositing User: Ilian Iliev
Date Deposited: 10 Jun 2013 07:25
Last Modified: 15 Mar 2017 02:14

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