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

Matthew A. Schenker, Richard S. Ellis, Nick P. Konidaris, Daniel P Stark

Research output: Contribution to journalArticle

134 Citations (Scopus)

Abstract

The redshift-dependent fraction of color-selected galaxies revealing Lyman alpha (Lyα) emission, x 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 improving constraints on the evolving neutral fraction over 6 < z < 8 and the implications for cosmic reionization.

Original languageEnglish (US)
Article number20
JournalAstrophysical Journal
Volume795
Issue number1
DOIs
StatePublished - Nov 1 2014

Fingerprint

intergalactic media
visibility
estimating
galaxies
gas
near infrared
scattering
dust
method
neutral gases
spectrographs
infrared spectra
slopes
continuums
color
by-product
estimates
gases

Keywords

  • dark ages
  • first stars - galaxies
  • high-redshift
  • reionization

ASJC Scopus subject areas

  • Space and Planetary Science
  • Astronomy and Astrophysics

Cite this

Line-emitting galaxies beyond a redshift of 7 : An improved method for estimating the evolving neutrality of the intergalactic medium. / Schenker, Matthew A.; Ellis, Richard S.; Konidaris, Nick P.; Stark, Daniel P.

In: Astrophysical Journal, Vol. 795, No. 1, 20, 01.11.2014.

Research output: Contribution to journalArticle

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