A galaxy at a redshift z = 6.96

Abstract

When galaxy formation started in the history of the Universe remains unclear. Studies of the cosmic microwave background indicate that the Universe, after initial cooling (following the Big Bang), was reheated and reionized by hot stars in newborn galaxies at a redshift in the range 6 < z < 14 (ref. 1). Though several candidate galaxies at redshift z > 7 have been identified photometrically (refs 2,3), galaxies with spectroscopically confirmed redshifts have been confined to z < 6.6 (refs. 4-8). Here we report a spectroscopic redshift of z = 6.96 (corresponding to just 750 Myr after the Big Bang) for a galaxy whose spectrum clearly shows Lyman-alpha emission at 9,682 A, indicating active star formation at a rate of about 10 M_sun/yr, where M_sun us the mass of the Sun. This demonstrates that galaxy formation was under way when the Universe was only about 6 per cent of its present age. The number density of galaxies at z = 7 seems to be only 18-36 per cent of the density at z = 6.6.

10 pages, 3 figure, 1 table

References in corpus (23)

• Stellar population synthesis at the resolution of 2003
• Star Formation in Galaxies Along the Hubble Sequence
• Large scale bias and the peak background split
• Three Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Polarization Analysis
• Subaru Prime Focus Camera -- Suprime-Cam --
• Evolution of the Ionizing Background and the Epoch of Reionization from the Spectra of z~6 Quasars
• The End of the Reionization Epoch Probed by Ly-alpha Emitters at z=6.5 in the Subaru Deep Field
• Luminosity functions of Lyman-alpha emitters at z=6.5, and z=5.7: evidence against reionization at z=6
• A Redshift z = 6.56 Galaxy Behind the Cluster Abell 370
• The Subaru Deep Field Project: Lyman$\alpha$ Emitters at Redshift of 6.6
• The Discovery of Primeval Large-Scale Structures with Forming Clusters at Redshift 6
• Probing reionization with Lyman-alpha emission lines
• The Luminosity Function of Lyman Alpha Emitters at Redshift z~5.7
• The Subaru Deep Field: The Optical Imaging Data
• Current Performance and On-Going Improvements of the 8.2 m Subaru Telescope
• An Extremely Luminous Galaxy at z=5.74
• A Subaru Search for Lyman$\alpha$ Emitters at Redshift 5.7
• Spitzer and Hubble Constraints on the Physical Properties of the z~7 Galaxy Strongly Lensed by Abell 2218
• Constraints on z~10 Galaxies from the Deepest HST NICMOS Fields
• A deep, narrow J-band search for proto-galactic Lyman Alpha emission at redshifts z~9
• DAzLE: The Dark Ages z (redshift) Lyman-alpha Explorer
• Searching for the Sources Responsible for Cosmic Reionization: Probing 7 < z < 10 and Beyond
• First Light and Reionization: A Conference Summary

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