2014/12/31 by Alan Dressler, Alaina Henry, Crystal L. Martin +4 · 1 citation
Physics and Astronomy · #Astronomy #Astrophysical Phenomena and Observations #Astrophysics #Extrapolation #Flux (metallurgy) #Galaxies: Formation, Evolution, Phenomena #Galaxy #Gamma-ray bursts and supernovae #Luminosity #Luminosity function #Physics #Redshift #Reionization #Statistics #astro-ph.GA
paper · pdf · doi:10.1088/0004-637x/806/1/19
12 pages, 5 figures
arxiv created 2015/04/23 · openalex publication_date 2015/06/03 · arxiv updated 2015/06/11 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
We report the first direct and robust measurement of the faint-end slope of the Ly α emitter (LAE) luminosity function (LF) at z = 5.7. Candidate LAEs from a low-spectral-resolution blind search with IMACS on Magellan-Baade were targeted at higher resolution to distinguish high-redshift LAEs from foreground galaxies. All but 2 of our 42 single-emission-line systems have flux ergs s −1 cm −2 , making these the faintest emission-lines observed for a z = 5.7 sample with known completeness , an essential property for determining the faint end slope of the LAE LF. We find 13 LAEs as compared to 29 foreground galaxies, in very good agreement with the modeled foreground counts predicted in Dressler et al. that had been used to estimate a faint-end slope of α = −2.0 for the LAE LF. A 32% LAE fraction, LAE/(LAE+foreground) within the flux interval ergs s −1 cm −2 constrains the faint end slope of the LF to (1 σ ). We show how this steep LF should provide, to the limit of our observations, −16, more than 20% of the flux necessary to maintain ionization at z = 5.7, with a factor of 10 extrapolation in flux reaching more than 50%. This is in addition to the comparable contribution by brighter Lyman Break Galaxies −18. We suggest that this bodes well for a sufficient supply of Lyman continuum photons by similar, low-mass star-forming galaxies within the reionization epoch at , only 250 Myr earlier.