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arXiv · 1701.05193

A High Space Density of Luminous Lyman Alpha Emitters at z~6.5

Micaela B. Bagley·Claudia Scarlata·Alaina Henry·Marc Rafelski·Matthew Malkan·Harry Teplitz·Y. Sophia Dai·Ivano Baronchelli·James Colbert·Michael Rutkowski·Vihang Mehta·Alan Dressler·Patrick McCarthy·Andrew Bunker·Hakim Atek·Thibault Garel·Crystal L. Martin·Nimish Hathi·Brian Siana
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Abstract

We present the results of a systematic search for Lyman-alpha emitters (LAEs) at $6 \lesssim z \lesssim 7.6$ using the HST WFC3 Infrared Spectroscopic Parallel (WISP) Survey. Our total volume over this redshift range is $\sim 8 \times10^5$ Mpc$^3$, comparable to many of the narrowband surveys despite their larger area coverage. We find two LAEs at $z=6.38$ and $6.44$ with line luminosities of L$_{\mathrm{Ly}\alpha} \sim 4.7 \times 10^{43}$ erg s$^{-1}$, putting them 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. The WISP LAEs have a high number density of $7.7\times10^{-6}$ Mpc$^{-3}$. We argue that the LAEs reside in Mpc-scale ionized bubbles that allow the Lyman-alpha photons to redshift out of resonance before encountering the neutral IGM. We discuss possible ionizing sources and conclude that the observed LAEs alone are not sufficient to ionize the bubbles.

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Micaela B. Bagley, Claudia Scarlata, Alaina Henry, Marc Rafelski, Matthew Malkan, Harry Teplitz, Y. Sophia Dai, Ivano Baronchelli, James Colbert, Michael Rutkowski, Vihang Mehta, Alan Dressler, Patrick McCarthy, Andrew Bunker, Hakim Atek, Thibault Garel, Crystal L. Martin, Nimish Hathi, Brian Siana. 2017-01-18. A High Space Density of Luminous Lyman Alpha Emitters at z~6.5. https://doi.org/10.3847/1538-4357%2F837%2F1%2F11

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