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Title: The Radiative Feedback of the First Cosmological Objects

Abstract

In hierarchical models of structure formation, an early cosmic UV background (UVB) is produced by the small (T{sub vir}(less-or-similar sign)10{sup 4} K) halos that collapse before reionization. The UVB at energies below 13.6 eV suppresses the formation of stars or black holes inside small halos by photodissociating their only cooling agent, molecular H{sub 2}. We self-consistently compute the buildup of the early UVB in Press-Schechter models, coupled with H{sub 2} photodissociation both in the intergalactic medium (IGM) and inside virialized halos. We find that the intergalactic H{sub 2} has a negligible effect on the UVB, both because its initial optical depth is small ((less-or-similar sign)0.1) and because it is photodissociated at an early stage. If the UV sources in the first collapsed halos are stars, then their UV flux suppresses further star formation inside small halos. This results in a pause in the buildup of the UVB, and reionization is delayed until larger halos (T{sub vir}(greater-or-similar sign)10{sup 4} K) collapse. If the small halos host miniquasars with hard spectra extending to {approx}1 keV, then their X-rays balance the effects of the UVB, the negative feedback does not occur, and reionization could be caused by the small halos. (c) 2000 Themore » American Astronomical Society.« less

Authors:
; ;
Publication Date:
OSTI Identifier:
20217418
Resource Type:
Journal Article
Journal Name:
Astrophysical Journal
Additional Journal Information:
Journal Volume: 534; Journal Issue: 1; Other Information: PBD: 1 May 2000; Journal ID: ISSN 0004-637X
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; COSMOLOGY; BACKGROUND RADIATION; ULTRAVIOLET SPECTRA; HYDROGEN; BLACK HOLES; IONIZATION; THEORETICAL DATA

Citation Formats

Haiman, Zoltan, Abel, Tom, and Rees, Martin J. The Radiative Feedback of the First Cosmological Objects. United States: N. p., 2000. Web. doi:10.1086/308723.
Haiman, Zoltan, Abel, Tom, & Rees, Martin J. The Radiative Feedback of the First Cosmological Objects. United States. doi:10.1086/308723.
Haiman, Zoltan, Abel, Tom, and Rees, Martin J. Mon . "The Radiative Feedback of the First Cosmological Objects". United States. doi:10.1086/308723.
@article{osti_20217418,
title = {The Radiative Feedback of the First Cosmological Objects},
author = {Haiman, Zoltan and Abel, Tom and Rees, Martin J.},
abstractNote = {In hierarchical models of structure formation, an early cosmic UV background (UVB) is produced by the small (T{sub vir}(less-or-similar sign)10{sup 4} K) halos that collapse before reionization. The UVB at energies below 13.6 eV suppresses the formation of stars or black holes inside small halos by photodissociating their only cooling agent, molecular H{sub 2}. We self-consistently compute the buildup of the early UVB in Press-Schechter models, coupled with H{sub 2} photodissociation both in the intergalactic medium (IGM) and inside virialized halos. We find that the intergalactic H{sub 2} has a negligible effect on the UVB, both because its initial optical depth is small ((less-or-similar sign)0.1) and because it is photodissociated at an early stage. If the UV sources in the first collapsed halos are stars, then their UV flux suppresses further star formation inside small halos. This results in a pause in the buildup of the UVB, and reionization is delayed until larger halos (T{sub vir}(greater-or-similar sign)10{sup 4} K) collapse. If the small halos host miniquasars with hard spectra extending to {approx}1 keV, then their X-rays balance the effects of the UVB, the negative feedback does not occur, and reionization could be caused by the small halos. (c) 2000 The American Astronomical Society.},
doi = {10.1086/308723},
journal = {Astrophysical Journal},
issn = {0004-637X},
number = 1,
volume = 534,
place = {United States},
year = {2000},
month = {5}
}