Modeling Lyman continuum emission from young galaxies

Abstract

Based on cosmological simulations, we model Lyman continuum emission from a sample of 11 high-redshift star forming galaxies spanning a mass range of a factor 20. Each of the 11 galaxies has been simulated both with a Salpeter and a Kroupa initial mass function (IMF). We find that the Lyman continuum (LyC) luminosity of an average star forming galaxy in our sample declines from z=3.6 to 2.4 due to the steady gas infall and higher gas clumping at lower redshifts, increasingly hampering the escape of ionizing radiation. The galaxy-to-galaxy variation of apparent LyC emission at a fixed redshift is caused in approximately equal parts by the intrinsic variations in the LyC emission and by orientation effects. The combined scatter of an order of magnitude can explain the variance in the far-UV spectra of high-redshift galaxies detected by Shapley et al. (2006). Our results imply that the cosmic galactic ionizing UV luminosity would be monotonically decreasing from z=3.6 to 2.4, curiously anti-correlated with the star formation rate in the smaller galaxies, which on average rises during this redshift interval.

8 pages, 12 figures, ApJ, in press

References in corpus (2)

• Evolution of the Luminosity Function, Star Formation Rate, Morphology and Size of Star-forming Galaxies Selected at Rest-frame 1500A and 2800A
• Lyman alpha Resonant Scattering in Young Galaxies - Predictions from Cosmological Simulations

Cited by in corpus (5)

• Lyman alpha Radiative Transfer in Cosmological Simulations using Adaptive Mesh Refinement
• A Monte Carlo simulation of the intergalactic absorption and the detectability of the Lyman continuum from distant galaxies
• Ongoing Galactic Accretion: Simulations and Observations of Condensed Gas in Hot Halos
• Are There Enough Ionizing Photons to Reionize the Universe by z=6?
• Where are the Cosmic Metals at z~3?