paper

Feedback-regulated star formation and escape of LyC photons from mini-haloes during reionisation

arXiv:1608.04762 · doi:10.1093/mnras/stx052

Abstract

Reionisation in the early Universe is likely driven by dwarf galaxies. Using cosmological radiation-hydrodynamic simulations, we study star formation and the escape of Lyman continuum (LyC) photons from mini-haloes with . Our simulations include a new thermo-turbulent star formation model, non-equilibrium chemistry, and relevant stellar feedback processes (photoionisation by young massive stars, radiation pressure, and mechanical supernova explosions). We find that feedback reduces star formation very efficiently in mini-haloes, resulting in the stellar mass consistent with the slope and normalisation reported in Kimm \& Cen and the empirical stellar mass-to-halo mass relation derived in the local Universe. Because star formation is stochastic and dominated by a few gas clumps, the escape fraction in mini-haloes is generally determined by radiation feedback (heating due to photo-ionisation), rather than supernova explosions. We also find that the photon number-weighted mean escape fraction in mini-haloes is higher (-) than that in atomic-cooling haloes, although the instantaneous fraction in individual haloes varies significantly. The escape fraction from Pop III stars is found to be significant () only when the mass is greater than 100\,\msun. Based on simple analytic calculations, we show that LyC photons from mini-haloes are, despite their high escape fractions, of minor importance for reionisation due to inefficient star formation. We confirm previous claims that stars in atomic-cooling haloes with masses are likely to be the most important source of reionisation.

22 pages, 15 figures, Accepted for the publication in MNRAS

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