SCIENCE@home

The visibility of Lyman α emitters: constraining reionization, ionizing photon escape fractions and dust

A. Hutter,P. Dayal,A. Partl,V. M. L. F. A. Potsdam,H Germany,U. Edinburgh,UK.

Published 2014 in Monthly Notices of the Royal Astronomical Society

ABSTRACT

We couple state of the art cosmological simulations (GADGET-2) with a dust model and a radiative transfer code (pCRASH) to build a complete model for high-redshift Lyman Alpha emitters (LAEs). Identifying simulated galaxies with dust-attenuated UV magnitudes of MUV 6 −17 as Lyman Break Galaxies (LBGs), we successfully validate our simulations by comparing against observed LBG ultraviolet luminosity functions (UV LFs), stellar mass functions, stellar mass densities (SMD) and specific star formation rates (sSFR) at z ≃ 6 − 8. Due to the poor constraints available on the escape fraction of H I ionizing photons (fesc) from galaxies, we use five different values fesc = 0.05,0.25,0.5,0.75,0.95 to post-process the cosmological simulation with pCRASH. Starting from a completely neutral Universe, we run pCRASH until reionization is complete, i.e. the average neutral hydrogen (H I ) fraction drops to hχHIi ≃10 4 . For a given fesc and hχHIicombination, the only free-parameter left to match model results to observations is the relative escape of Lyman Alpha (Lyα ) and continuum photons from the galactic environment (f�/fc). Starting from a scenario wherein dust is homogeneously distributed (f�/fc ≃ 0.68), we find that the observed LAE UV and Lyα luminosity functions (LFs) jointly constrain fesc ≃ 0.05 and hχHIi 6 0.1. In the scenario that dust is clumped, we find a three-dimensional degeneracy between fesc, hχHIi and f�/fc such that a decrease in the intrinsic Lyα luminosity can be compensated by an increase in the Lyα transmission through the intergalactic medium and/or an increasing Lyα escape out of the galactic environment. In the latter scenario, the theoretical model can be reconciled with observations for a much larger parameter space: hχHIi ≃0.5−10 4 , fesc ≃ 0.05−0.50 and f�/fc = 0.6−1.8. In other words, if dust is indeed clumped in the interstellar medium of high-redshift galaxies, we can not differentiate between a Universe which is either completely ionized or half neutral, or has an fesc ranging between 5-50%.

PUBLICATION RECORD

CITATION MAP

EXTRACTION MAP

CLAIMS

  • No claims are published for this paper.

CONCEPTS

  • No concepts are published for this paper.

REFERENCES

Showing 1-100 of 110 references · Page 1 of 2

12
Next

CITED BY

Showing 1-37 of 37 citing papers · Page 1 of 1