University of Minnesota
School of Physics & Astronomy

Cosmology Lunchtime Seminar

Monday, May 1st 2017
12:15 pm:
Speaker: Micaela Bagley, UMN
Subject: A High Space Density of Luminous Lyman-alpha Emitters at z~6.5

I will present the results of a systematic search for Lyman-alpha emitters (LAEs) at 6 < z < 7.6 using the HST WFC3 Infrared Spectroscopic Parallel (WISP) Survey. Our survey covers a volume ~ 8x10^5 Mpc^3, comparable to many of the narrowband surveys despite their larger area coverage. We identify two LAEs at z ~ 6.4, which are among the brightest LAEs discovered at these redshifts. Taking advantage of the broad spectral coverage of WISP, we are able to rule out almost all lower-redshift contaminants. These LAEs reside in Mpc-scale ionized bubbles that allow the Ly-alpha photons to redshift out of resonance before encountering the neutral IGM. Based on the observed constraints, we conclude that the observed LAEs alone are not sufficient to ionize their surrounding bubbles.

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