Journal Article

Radiation from early black holes – I. Effects on the neutral intergalactic medium

E. Ripamonti, M. Mapelli and S. Zaroubi

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 387, issue 1, pages 158-172
Published in print June 2008 | ISSN: 0035-8711
Published online May 2008 | e-ISSN: 1365-2966 | DOI:
Radiation from early black holes – I. Effects on the neutral intergalactic medium

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In the pre-reionization Universe, the regions of the intergalactic medium (IGM) which are far from luminous sources are the last to undergo reionization. Until then, they should be scarcely affected by stellar radiation; instead, the X-ray emission from an early black hole (BH) population can have much larger influence. We investigate the effects of such emission, looking at a number of BH model populations (differing for the cosmological density evolution of BHs, the BH properties, and the spectral energy distribution of the BH emission). We find that BH radiation can easily heat the IGM to 103–104K, while achieving partial ionization. The most interesting consequence of this heating is that BHs are expected to induce a 21-cm signal (δTb∼ 20–30 mK at z≲ 12) which should be observable with forthcoming experiments (e.g. LOFAR). We also find that at z≲ 10 BH emission strongly increases the critical mass separating star-forming and non-star-forming haloes.

Keywords: black hole physics; galaxies: formation; intergalactic medium; cosmology: theory; diffuse radiation

Journal Article.  12384 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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