Publications by authors named "G B Brammer"
The most distant galaxies detected were seen when the Universe was a scant 5% of its current age. At these times, progenitors of galaxies such as the Milky Way were about 10,000 times less massive. Using the James Webb Space Telescope (JWST) combined with magnification from gravitational lensing, these low-mass galaxies can not only be detected but also be studied in detail.
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- Recent observations from the James Webb Space Telescope (JWST) have found many massive-galaxy candidates in the early Universe, stretching further back in time and at lower brightness levels than previously seen.
- These findings initially posed challenges to the Λ cold dark-matter model, but the new study's results show no significant conflicts when accounting for spectroscopic redshifts.
- The research highlights three ultra-massive galaxies that convert a notably high percentage of baryons into stars, suggesting they play a significant role in cosmic star-formation rates at redshifts 5 to 6.
The Cosmic Gems arc is among the brightest and highly magnified galaxies observed at redshift z ≈ 10.2 (ref. ).
View Article and Find Full Text PDFPrimordial neutral atomic gas, mostly composed of hydrogen, is the raw material for star formation in galaxies. However, there are few direct constraints on the amount of neutral atomic hydrogen (H i) in galaxies at early cosmic times. We analyzed James Webb Space Telescope (JWST) near-infrared spectroscopy of distant galaxies, at redshifts ≳8.
View Article and Find Full Text PDFThe identification of sources driving cosmic reionization, a major phase transition from neutral hydrogen to ionized plasma around 600-800 Myr after the Big Bang, has been a matter of debate. Some models suggest that high ionizing emissivity and escape fractions (f) from quasars support their role in driving cosmic reionization. Others propose that the high f values from bright galaxies generate sufficient ionizing radiation to drive this process.
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