![]() ![]() Constraining the evolution of the ionizing background and the epoch of reionization with z ∼6 quasars. Keck spectroscopy of faint 3>z>7 Lyman break galaxies: a high fraction of line emitters at redshift six. A dust-obscured massive maximum-starburst galaxy at a redshift of 6.34. Keck spectroscopy of 3 < z < 7 faint Lyman break galaxies: the importance of nebular emission in understanding the specific star formation rate and stellar mass density. A new multifield determination of the galaxy luminosity function at z = 7–9 incorporating the 2012 Hubble Ultra-Deep Field imaging. CANDELS: The evolution of galaxy rest-frame ultraviolet colors from z = 8 to 4. ![]() Galaxies at z = 6–9 from the WFC3/IR imaging of the Hubble Ultra Deep Field. On the stellar populations and evolution of star-forming galaxies at 6.3 ≤ z ≤ 8.6. MOSFIRE, the multi-object spectrometer for infra-red exploration at the Keck Observatory. CANDELS: The Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey – The Hubble Space Telescope observations, imaging data products, and mosaics. CANDELS: The Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey. The star formation rate function for redshift z ∼ 4–7 galaxies: evidence for a uniform buildup of star-forming galaxies during the first 3 Gyr of cosmic time. Spectroscopic confirmation of z ∼ 7 Lyman break galaxies: probing the earliest galaxies and the epoch of reionization. Statistics of 207 Ly α emitters at a redshift near 7: constraints on reionization and galaxy formation models. The end of the reionization epoch probed by Ly α emitters at z = 6.5 in the Subaru deep field. The first systematic survey for Ly α emitters at z = 7.3 with red-sensitive Subaru/Suprime-Cam. Spectroscopic confirmation of three z-dropout galaxies at z = 6.844–7.213: demographics of Ly α emission in z ∼ 7 galaxies. Keck spectroscopy of faint 3 < z < 8 Lyman break galaxies: evidence for a declining fraction of emission line sources in the redshift range 6 < z < 8. ![]() Spectroscopic confirmation of two Lyman break galaxies at redshift beyond 7. Such a galaxy is unexpected in a survey of our size 9, suggesting that the early Universe may harbour a larger number of intense sites of star formation than expected. 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. This galaxy’s colours are consistent with significant metal content, implying that galaxies become enriched rapidly. 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. We detect a near-infrared emission line from only a single galaxy, confirming that some process is making Lyman α difficult to detect. Here we report a deep near-infrared spectroscopic survey of 43 photometrically-selected galaxies with z > 6.5. The small samples and limited depth of previous observations, however, makes these conclusions tentative. 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 gas 3, 5, 6, 7, 8. 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). ![]()
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