Publication Date:
2013-10-25
Description:
Of several dozen galaxies observed spectroscopically that are candidates for having a redshift (z) in excess of seven, only five have had their redshifts confirmed via Lyman alpha emission, at z = 7.008, 7.045, 7.109, 7.213 and 7.215 (refs 1-4). The small fraction of confirmed galaxies may indicate that the neutral fraction in the intergalactic medium rises quickly at z 〉 6.5, given that Lyman alpha is resonantly scattered by neutral gas. The small samples and limited depth of previous observations, however, makes these conclusions tentative. Here we report a deep near-infrared spectroscopic survey of 43 photometrically-selected galaxies with z 〉 6.5. We detect a near-infrared emission line from only a single galaxy, confirming that some process is making Lyman alpha difficult to detect. The detected emission line at a wavelength of 1.0343 micrometres is likely to be Lyman alpha emission, placing this galaxy at a redshift z = 7.51, an epoch 700 million years after the Big Bang. This galaxy's colours are consistent with significant metal content, implying that galaxies become enriched rapidly. We calculate a surprisingly high star-formation rate of about 330 solar masses per year, which is more than a factor of 100 greater than that seen in the Milky Way. Such a galaxy is unexpected in a survey of our size, suggesting that the early Universe may harbour a larger number of intense sites of star formation than expected.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Finkelstein, S L -- Papovich, C -- Dickinson, M -- Song, M -- Tilvi, V -- Koekemoer, A M -- Finkelstein, K D -- Mobasher, B -- Ferguson, H C -- Giavalisco, M -- Reddy, N -- Ashby, M L N -- Dekel, A -- Fazio, G G -- Fontana, A -- Grogin, N A -- Huang, J-S -- Kocevski, D -- Rafelski, M -- Weiner, B J -- Willner, S P -- England -- Nature. 2013 Oct 24;502(7472):524-7. doi: 10.1038/nature12657.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉The University of Texas at Austin, 2515 Speedway, Stop C1400, Austin, Texas 78712, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/24153304" target="_blank"〉PubMed〈/a〉
Print ISSN:
0028-0836
Electronic ISSN:
1476-4687
Topics:
Biology
,
Chemistry and Pharmacology
,
Medicine
,
Natural Sciences in General
,
Physics
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