Journal Article

Simulating high-redshift galaxies

Ruben Salvaterra, Andrea Ferrara and Pratika Dayal

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 414, issue 2, pages 847-859
Published in print June 2011 | ISSN: 0035-8711
Published online June 2011 | e-ISSN: 1365-2966 | DOI:
Simulating high-redshift galaxies

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Recent observations have gathered a considerable sample of high-redshift galaxy candidates and determined the evolution of their luminosity function (LF). To interpret these findings, we use cosmological SPH simulations including, in addition to standard physical processes, a detailed treatment of the Pop III−Pop II transition in early objects. The simulated high-z galaxies match remarkably well the amplitude and slope of the observed LF in the redshift range 5 < z < 10. The LF shifts towards fainter luminosities with increasing redshift, while its faint-end slope keeps an almost constant value, α≈−2. The stellar populations of high-z galaxies have ages of 100–300 (40–130) Myr at z= 5 (z= 7–8), implying an early (z > 9.4) start of their star formation activity; the specific star formation rate is almost independent of galactic stellar mass. These objects are enriched rapidly with metals and galaxies identified by HST/WFC3 () show metallicities ≈0.1 Z even at z= 7–8. Most of the simulated galaxies at z≈ 7 (noticeably the smallest ones) are virtually dust-free, and none of them has an extinction larger than E(BV) = 0.01. The bulk (50 per cent) of the ionizing photons is produced by objects populating the faint end of the LF (), which JWST will resolve up to z= 7.3. Pop III stars continue to form essentially at all redshifts; however, at z= 6 (z= 10) the contribution of Pop III stars to the total galactic luminosity is always less than 5 per cent for (). The typical high-z galaxies closely resemble the GRB host galaxy population observed at lower redshifts, strongly encouraging the use of GRBs to detect the first galaxies.

Keywords: methods: numerical; galaxies: high-redshift; galaxies: luminosity function, mass function; cosmology: theory

Journal Article.  10033 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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