Keck Spectroscopy of Faint 3<z<7 Lyman Break Galaxies:- II. A High Fraction of Line Emitters at Redshift Six - Astrophysics > Cosmology and Nongalactic AstrophysicsReportar como inadecuado




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Abstract: As Lyman-alpha photons are scattered by neutral hydrogen, a change withredshift in the Lyman-alpha equivalent width distribution of distant galaxiesoffers a promising probe of the degree of ionization in the intergalacticmedium and hence when cosmic reionization ended. This simple test iscomplicated by the fact that Lyman-alpha emission can also be affected by theevolving astrophysical details of the host galaxies. In the first paper in thisseries, we demonstrated both a luminosity and redshift dependent trend in thefraction of Lyman-alpha emitters seen within color-selected Lyman-breakgalaxies LBGs over the range 325A emission, an increase of 1.6x from a similar sample observed at z~4. With atotal sample of 74 z~6 LBGs, we determine the luminosity-dependent Lyman-alphaequivalent width distribution. Assuming continuity in these trends to the newpopulation of z~7 sources located with the Hubble WFC3-IR camera, we predictthat unless the neutral fraction rises in the intervening 200 Myr, the successrate for spectroscopic confirmation using Lyman-alpha emission should be high.



Autor: Daniel P. Stark, Richard S. Ellis, Masami Ouchi

Fuente: https://arxiv.org/







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