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Detecting the rise and fall of the first stars by their impact on cosmic reionization

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posted on 2023-06-08, 15:12 authored by Kyungjin Ahn, Ilian IlievIlian Iliev, Paul R Shapiro, Garrelt Mellema, Jun Koda, Yi Mao
The intergalactic medium was reionized before redshift z ~ 6, most likely by starlight which escaped from early galaxies. The very ?rst stars formed when hydrogen molecules (H2) cooled gas inside the smallest galaxies, minihalos of mass between 105 and 108 solar masses, before redshift z ~ 40. Minihalo stars then started reionization but could not ?nish it before the rising background of H2-dissociating soft-ultraviolet starlight choked them o?. We con?rm this hypothesis by the ?rst large-scale radiative transfer simulations to include minihalo sources and their suppression. We show that reionization began much earlier with minihalo sources than without, and was greatly extended, which boosts the intergalactic electron-scattering optical depth and the large-angle polarization ?uctuations of the cosmic microwave background signi?cantly. Although within current WMAP uncertainties, this boost should be readily detectable by Planck. If reionization ended as late as z ov 7, as suggested by other observations, Planck will thereby see the signature of the ?rst stars at high redshift, currently undetectable by any other probe. We also show that minimal reionization models satisfying both the late reionization condition, zov . 7, and the large optical depth condition, tes & 0.085, can be distinguished from our ?ducial model under the same constraints by Planck at high con?dence level.

History

Publication status

  • Published

File Version

  • Published version

Journal

Astrophysical Journal Letters

ISSN

2041-8205

Publisher

Institute of Physics

Issue

1

Volume

756

Page range

L16

Department affiliated with

  • Physics and Astronomy Publications

Full text available

  • Yes

Peer reviewed?

  • Yes

Legacy Posted Date

2013-06-10

First Open Access (FOA) Date

2013-06-10

First Compliant Deposit (FCD) Date

2013-06-07

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