A High Space Density of Luminous Lyα Emitters at $z\sim 6.5$ by Bagley, M, Scarlata, C, Henry, A, Rafelski, M, Malkan, M, Teplitz, H, Dai, Y, Baronchelli, I, Colbert, J, Rutkowski, M, Mehta, V, Dressler, A, McCarthy, P, Bunker, A, Atek, H, Garel, T, Martin, C, Hathi, N, Siana, B

“…We argue that the LAEs reside in megaparsec-scale ionized bubbles that allow the Lyα photons to redshift out of resonance before encountering the neutral intergalactic medium. We discuss possible ionizing sources and conclude that the observed LAEs alone are not sufficient to ionize the bubbles.…”

No Evidence for Lyman-alpha Emission in Spectroscopy of z > 7 Candidate Galaxies by Caruana, J, Bunker, A, Wilkins, S, Stanway, E, Lacy, M, Jarvis, M, Lorenzoni, S, Hickey, S

“…A simple model where the fraction of high rest-frame equivalent width emitters follows the trend seen at z=3-6.5 is inconsistent with our non-detections at z=7-9 at the ~ 1-sigma level for spectrally unresolved lines, which may indicate that a significant neutral HI fraction in the intergalactic medium suppresses the Lyman-alpha line in z-drop and Y-drop galaxies at z > 7.…”

Spectroscopy of z similar to 7 candidate galaxies: using Lyman alpha to constrain the neutral fraction of hydrogen in the high-redshift universe by Caruana, J, Bunker, A, Wilkins, S, Stanway, E, Lorenzoni, S, Jarvis, M, Ebert, H

“…This may indicate that a signicant neutral HI fraction in the intergalactic medium suppresses Lyman α, with an estimated neutral fraction χHI ~ 0.5, in agreement with other estimates. © 2014 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society.…”

Galaxies at high redshift and reionization by Bunker, A, Stanway, E, Ellis, R, Lacy, M, McMahon, R, Stark, D, Chiu, K, Eyles, L

“…We are now exploring redshifts of 6 and beyond, when the Universe was less than a billion years old, an epoch when the previously neutral intergalactic medium was reionized. The continuing discovery of galaxies at progressively higher and higher redshifts has been driven by the availability of large telescopes on the ground and in space, improvements in detector technology, and new search strategies. …”

Spectroscopic analysis of primeval galaxy candidates by Caruana, J

“…A model where the fraction of high rest-frame equivalent width emitters follows the trend seen at z = 3−6.5 is inconsistent with these non-detections at z = 7−9 at a confidence level of ∼ 91%, which may indicate that a significant neutral HI fraction (χHI) in the intergalactic medium suppresses the Lyman-α line at z > 7. …”

Keck spectroscopy of faint 3 < z < 7 Lyman break galaxies - I. New constraints on cosmic reionization from the luminosity and redshift-dependent fraction of Lyman alpha emiss... by Stark, D, Ellis, R, Chiu, K, Ouchi, M, Bunker, A

“…In order to distinguish the effects of reionization from other factors which affect the Lyα fraction [e.g. dust, interstellar medium (ISM) kinematics], we study the luminosity and redshift-dependence of the Lyα fraction over 3 ≲z≲ 6, when the intergalactic medium (IGM) is known to be ionized. These results reveal that low-luminosity galaxies show strong Lyα emission much more frequently (xLyα= 0.47 ± 0.16 at MUV=-19) than luminous systems (xLyα= 0.08 ± 0.02 at MUV=-21), and that at fixed luminosity, the prevalence of strong Lyman α emission increases moderately with redshift over 3 < z < 6 (d xLyα/d z= 0.05 ± 0.03). …”