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A Galaxy at z = 6.545 and Constraints on the Epoch of Reionization

Daniel Stern·Sarah A. Yost·Megan E. Eckart·Fiona A. Harrison·David J. Helfand·S. G. Djorgovski·Sangeeta Malhotra·James E. Rhoads
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Abstract

We report the discovery of a Lyman-alpha-emitting galaxy at redshift z=6.545 serendipitously identified in the course of spectroscopic follow-up of hard X-ray sources on behalf of the Serendipitous Extragalactic X-Ray Source Identification (SEXSI) survey. The line flux of the galaxy, 2.1e-17 erg/cm2/s, is similar to line fluxes probed by narrow-band imaging surveys; the 5.2 square-arcminutes surveyed implies a surface density of z~6.5 Lyman-alpha emitters somewhat higher than that inferred from narrow-band surveys. This source marks the sixth Lyman-alpha-emitting galaxy identified at z~6.5, a redshift putatively beyond the epoch of reionization when the damping wings of the neutral hydrogen of the intergalactic medium is capable of severely attenuating Lyman-alpha emission. By comparing the Lyman-alpha emitter luminosity functions at z~5.7 and z~6.5, we infer that the intergalactic medium may remain largely reionized from the local universe out to z~6.5.

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Daniel Stern, Sarah A. Yost, Megan E. Eckart, Fiona A. Harrison, David J. Helfand, S. G. Djorgovski, Sangeeta Malhotra, James E. Rhoads. 2004-07-19. A Galaxy at z = 6.545 and Constraints on the Epoch of Reionization. https://doi.org/10.1086/426423

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