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A galaxy rapidly forming stars 700 million years after the Big Bang at redshift 7.51


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 α emission, at z = 7.008, 7.045, 7.109, 7.213 and 7.215 (refs 1, 2, 3, 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 α is resonantly scattered by neutral gas3,5,6,7,8. 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 α difficult to detect. The detected emission line at a wavelength of 1.0343 micrometres is likely to be Lyman α 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 size9, suggesting that the early Universe may harbour a larger number of intense sites of star formation than expected.

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Figure 1: The observed NIR spectrum of the galaxy z8_GND_5296.
Figure 2: Images of z8_GND_5296.
Figure 3: Spectral energy distribution fitting of z8_GND_5296.


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We thank M. Dijkstra, J. Rhoads and S. Malhotra for conversations, as well as N. Konidaris and C. Steidel for assistance with the MOSFIRE data reduction pipeline. We also thank our Keck Support Astronomer G. Wirth for assistance during our observing run. S.L.F. acknowledges support from the University of Texas at Austin, the McDonald Observatory and NASA through a NASA Keck PI Data Award, administered by the NASA Exoplanet Science Institute. Data presented here were obtained at the W. M. Keck Observatory from telescope time allocated to NASA through the agency’s scientific partnership with the California Institute of Technology and the University of California. The Observatory was made possible by the financial support of the W. M. Keck Foundation. We recognize and acknowledge the cultural role and reverence that the summit of Mauna Kea has within the indigenous Hawaiian community. This work is also based in part on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555, as well as the Spitzer Space Telescope, which is operated by the Jet Propulsion Laboratory, California Institute of Technology under a contract with NASA.

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Authors and Affiliations



S.L.F. wrote the text, obtained and reduced the data and led the initial observing proposal. C.P. and M.D. assisted with the analysis of the data. M.S. and V.T. assisted with the observation planning and implementation. K.D.F. performed the Spitzer/IRAC photometry. A.M.K. was responsible for the reduction of the optical and NIR imaging data used to select the sample. G.G.F., M.L.N.A. and S.P.W. obtained and reduced the mid-infrared data. B.J.W. provided grism spectroscopic information. B.M., H.C.F., M.G., N.R., A.D., A.F., N.A.G., J.-S.H., D.K. and M.R. have contributed in their roles as members of the CANDELS and S-CANDELS teams, and assisted with the planning and interpretation of the observations.

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Correspondence to S. L. Finkelstein.

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The authors declare no competing financial interests.

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Finkelstein, S., Papovich, C., Dickinson, M. et al. A galaxy rapidly forming stars 700 million years after the Big Bang at redshift 7.51. Nature 502, 524–527 (2013).

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