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Title: Line-emitting galaxies beyond a redshift of 7: an improved method for estimating the evolving neutrality of the intergalactic medium

The redshift-dependent fraction of color-selected galaxies revealing Lyman alpha (Lyα) emission, x {sub Lyα} has become the most valuable constraint on the evolving neutrality of the early intergalactic medium. However, in addition to resonant scattering by neutral gas, the visibility of Lyα is also dependent on the intrinsic properties of the host galaxy, including its stellar population, dust content, and the nature of outflowing gas. Taking advantage of significant progress we have made in determining the line-emitting properties of z ≅ 4-6 galaxies, we propose an improved method, based on using the measured slopes of the rest-frame ultraviolet continua of galaxies, to interpret the growing body of near-infrared spectra of z > 7 galaxies in order to take into account these host galaxy dependencies. In a first application of our new method, we demonstrate its potential via a new spectroscopic survey of 7 < z < 8 galaxies undertaken with the Keck MOSFIRE spectrograph. Together with earlier published data, our data provide improved estimates of the evolving visibility of Lyα, particularly at redshift z ≅ 8. As a by-product, we also present a promising new line-emitting galaxy candidate, detected at 4.0σ at redshift z = 7.62. We discuss the improvingmore » constraints on the evolving neutral fraction over 6 < z < 8 and the implications for cosmic reionization.« less
Authors:
; ;  [1] ;  [2]
  1. Department of Astrophysics, California Institute of Technology, MC 249-17, Pasadena, CA 91125 (United States)
  2. Department of Astronomy and Steward Observatory, University of Arizona, Tucson, AZ 85721 (United States)
Publication Date:
OSTI Identifier:
22370330
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 795; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; BY-PRODUCTS; COLOR; DUSTS; EMISSION; GALAXIES; INFRARED SPECTRA; INTERGALACTIC SPACE; LYMAN LINES; RED SHIFT; RESONANCE SCATTERING; STARS; ULTRAVIOLET RADIATION; VISIBILITY