2009/06/09 by Hidenobu Yajima, Masayuki Umemura, Masao Mori +2 · 1 citation
Physics and Astronomy · #Astronomy #Astrophysics #Astrophysics and Cosmic Phenomena #Astrophysics and Star Formation Studies #Galaxies: Formation, Evolution, Phenomena #Galaxy #Ionization #Luminosity #Photoionization #Physics #Radiative transfer #Redshift #Reionization #Supernova #astro-ph.CO #astro-ph.GA
paper · pdf · doi:10.1111/j.1365-2966.2009.15195.x
8 pages, 4 figures, accepted for publication in MNRAS
arxiv created 2009/06/09 · openalex publication_date 2009/08/10 · arxiv updated 2015/05/13 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
In order to assess the contribution of Lyman break galaxies (LBGs) and Lyman α emitters (LAEs) at redshifts 3 < z < 7 to the ionization of intergalactic medium (IGM), we investigate the escape fractions of ionizing photons from supernova-dominated primordial galaxies by solving the three-dimensional (3D) radiative transfer. The model galaxy is employed from an ultra-high-resolution chemodynamic simulation of a primordial galaxy by Mori & Umemura, which well reproduces the observed properties of LAEs and LBGs. The total mass of model galaxy is 1011 M⊙. We solve not only photoionization but also collisional ionization by shocks. In addition, according to the chemical enrichment, we incorporate the effect of dust extinction, taking the size distributions of dust into account. As a result, we find that dust extinction reduces the escape fractions by a factor of 1.5–8.5 in the LAE phase and by a factor of 2.5–11 in the LBG phase, while the collisional ionization by shocks increases the escape fractions by a factor of ≈2. The resultant escape fractions are 0.07–0.47 in the LAE phase and 0.06–0.17 in the LBG phase. These results are well concordant with the recent estimations derived from the flux density ratio at 1500 to 900 Å of LAEs and LBGs. Combining the resultant escape fractions with the luminosity functions of LAEs and LBGs, we find that high-z LAEs and LBGs can ionize the IGM at z= 3–5. However, ionizing radiation from LAEs as well as LBGs falls short of ionizing the IGM at z > 6. That implies that additional ionization sources may be required at z > 6.