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A Keck Survey for Gravitationally Lensed Lyα Emitters in the Redshift Range 8.5 < z < 10.4: New Constraints on the Contribution of Low-Luminosity Sources to Cosmic Reionization

Stark, Daniel P. and Ellis, Richard S. and Richard, Johan and Kneib, Jean-Paul and Smith, Graham P. and Santos, Michael R. (2007) A Keck Survey for Gravitationally Lensed Lyα Emitters in the Redshift Range 8.5 < z < 10.4: New Constraints on the Contribution of Low-Luminosity Sources to Cosmic Reionization. Astrophysical Journal, 663 (1). pp. 10-28. ISSN 0004-637X. doi:10.1086/518098. https://resolver.caltech.edu/CaltechAUTHORS:20100204-153240241

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Abstract

We discuss new observational constraints on the abundance of faint high-redshift Lyα emitters secured from a deep Keck near-infrared spectroscopic survey that utilizes the strong magnification provided by lensing galaxy clusters. In each of nine clusters, we have undertaken a systematic "blind" search for line emission with NIRSPEC in the J band within carefully selected regions that offer very high magnifications (≳10×-50×) for background sources with redshifts z ≃ 10. The high magnification enables the detection of emission at unprecedented flux limits (10^(41)-10^(42) ergs s^(-1)). As the comoving volumes probed are small, our survey is designed to address the important question of whether low-luminosity galaxies could provide the dominant ionizing flux at z ~ 10. Our survey has yielded six promising (>5 σ) candidate Lyα emitters that lie between z = 8.7 and z = 10.2. We carefully discuss the validity of our detections and the likelihood that the detected line is Lyα in light of earlier, apparently false, claims. Lower redshift line interpretations can be excluded, with reasonable assumptions, through the nondetection of secondary emission in further spectroscopy undertaken with LRIS and NIRSPEC. Nonetheless, as a result of our tests, we argue that at least two of our candidates are likely to be at z ≃ 10. Given the small survey volume, this suggests there is a large abundance of low-luminosity star-forming sources at z ≃ 8-10. While the predicted reionization photon budget depends upon a large number of physical assumptions, our first glimpse at the z 10 universe suggests that low-luminosity star-forming galaxies contribute a significant proportion of the UV photons necessary for cosmic reionization.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1086/518098DOIArticle
http://www.iop.org/EJ/abstract/0004-637X/663/1/10PublisherArticle
ORCID:
AuthorORCID
Ellis, Richard S.0000-0001-7782-7071
Richard, Johan0000-0001-5492-1049
Kneib, Jean-Paul0000-0002-4616-4989
Smith, Graham P.0000-0003-4494-8277
Additional Information:© 2007 American Astronomical Society. Print publication: Issue 1 (2007 July 1); received 2006 October 12; accepted for publication 2007 February 20. We thank the anonymous referee and Avi Loeb for very helpful comments. We are indebted to George Becker for providing his spectroscopy reduction software and Tom Broadhurst for providing mass models for several of our survey clusters. We thank Mark Sullivan for observing and reducing data on the candidate Abell 68 c1 with LRIS. G. P. S. acknowledges support from a Royal Society University Research Fellowship. Faint-object nearinfrared spectroscopy at Keck is possible thanks to the dedicated efforts of instrumentalists and theKeck support staff; we thank Ian McLean, Jim Lyke, and Grant Hill for making this project possible. The authors recognize and acknowledge the very significant cultural role and reverence that the summit of Mauna Kea has always had within the indigenous Hawaiian community.We are most fortunate to have the opportunity to conduct observations from this mountain.
Funders:
Funding AgencyGrant Number
Royal SocietyUNSPECIFIED
Subject Keywords:cosmology: observations; galaxies: evolution; galaxies: formation; galaxies: high-redshift; gravitational lensing
Issue or Number:1
DOI:10.1086/518098
Record Number:CaltechAUTHORS:20100204-153240241
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20100204-153240241
Official Citation:A Keck Survey for Gravitationally Lensed Lyα Emitters in the Redshift Range 8.5 < z < 10.4: New Constraints on the Contribution of Low-Luminosity Sources to Cosmic Reionization Daniel P. Stark, Richard S. Ellis, Johan Richard, Jean-Paul Kneib, Graham P. Smith, and Michael R. Santos 2007 ApJ 663 10-28 doi: 10.1086/518098
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:17390
Collection:CaltechAUTHORS
Deposited By: Jason Perez
Deposited On:05 Feb 2010 18:09
Last Modified:08 Nov 2021 23:35

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