2001/10/31 by Massimo Ricotti, Nickolay Y. Gnedin, J. Michael Shull · 7 citations
Physics and Astronomy · #Astronomy and Astrophysical Research #Electrical and Electromagnetic Research #Galaxies: Formation, Evolution, Phenomena #Galaxy #Galaxy formation and evolution #Radiative transfer #Redshift #Reionization #Star formation #Stars #Universe #astro-ph
paper · pdf · doi:10.1086/341256
Accepted for publication on ApJ, 38 pages, including 18 figures and 1 table. Movies and a higher quality version of the paper (figures) are available at: http://casa.colorado.edu/~ricotti/MOVIES.html
arxiv created 2002/04/09 · openalex publication_date 2002/08/10 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
We use three-dimensional cosmological simulations with radiative transfer to study the formation and evolution of the first galaxies in a ΛCDM cosmology. The simulations include continuum radiative transfer using the optically thin variable Eddington tensor (OTVET) approximation and line radiative transfer in the H 2 Lyman-Werner bands of the UV background radiation. Chemical and thermal processes are treated in detail, particularly the ones relevant for H 2 formation and destruction. We find that the first luminous objects ("small-halo objects") are characterized by bursting star formation (SF) that is self-regulated by a feedback process acting on cosmological instead of galactic scales. The global SF history is regulated by the mean number of ionizing photons that escape from each source, UV ⟨ f esc ⟩. It is almost independent of the assumed SF efficiency parameter, * , and the intensity of the dissociating background. The main feedback process that regulates the SF is the reformation of H 2 in front of H II regions and inside relic H II regions. The H II regions remain confined inside filaments, maximizing the production of H 2 in overdense regions through cyclic destruction/reformation of H 2 . If UV ⟨ f esc ⟩ > 10 -7 / * , the SF is self-regulated, photoevaporation of small-halo objects dominates the metal pollution of the low-density intergalactic medium, and the mass of produced metals depends only on ⟨ f esc ⟩. If UV ⟨ f esc ⟩ ≲ 10 -7 / * , positive feedback dominates, and small-halo objects constitute the bulk of the mass in stars and metals until at least redshift z ~ 10. Small-halo objects cannot reionize the universe because the feedback mechanism confines the H II regions inside the large-scale structure filaments. In contrast to massive objects ("large halos"), which can reionize voids, small-halo objects partially ionize only the dense filaments while leaving the voids mostly neutral.