Reionization, as a research area, investigates the cosmic epoch during which the predominantly neutral intergalactic medium (IGM) produced after recombination was ionized by the first luminous sources, such as Population III stars, early galaxies, and possibly accreting black holes. It focuses on constraining the timing, morphology, and sources of ionizing radiation, as well as the feedback processes regulating early structure formation. Key observational probes include CMB optical depth measurements, high-redshift quasar spectra (Gunn–Peterson trough), Lyman-alpha emitters, and 21 cm tomography, while theoretical work employs radiative transfer, cosmological simulations, and semi-analytic models to connect reionization to galaxy formation and large-scale structure.
When the universe was still in its infancy—only 500 million years after the Big Bang, or about 3% of its current age—some of the universe's earliest stars and galaxies had already formed. Astronomers have long predicted that ...
Astrobiology
Sep 24, 2026
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When JWST's first science results started rolling in, it was a triumph for scientific vision and persistence. For years, the fate of the powerful space telescope was uncertain. It went way over budget, and for 25 years, troubling ...
Astronomy
Sep 14, 2026
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A new study analyzing the James Webb Space Telescope (JWST) spectra of more than 1,400 galaxies suggests a surprisingly small group of "leaky" galaxies was responsible for cosmic reionization. The paper outlining this work ...
Astronomers have identified one of the most distant candidate galaxies known to leak ionizing radiation—the same kind of radiation thought to have transformed the early universe during the epoch of reionization.
Astronomers using NASA's Hubble Space Telescope have found something they never expected—ultraviolet light from a galaxy that existed just 1.4 billion years after the Big Bang. That galaxy contains tightly clustered young ...
Astronomy
Jun 23, 2026
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34
Astronomers have discovered a huge reservoir of cold molecular gas, the direct fuel for star formation, in REBELS-25, a massive, star-forming galaxy. The team, led from Leiden University, focused on REBELS-25, seen when the ...
Astronomy
Jun 11, 2026
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Cornell astronomers are deploying a new instrument that grants them, for the first time, a better view of the universe's earliest galaxies, which can't be observed individually with traditional ground- or space-based telescopes.
Astronomy
May 12, 2026
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38
The NASA/ESA/CSA James Webb Space Telescope has topped itself once again, delivering on its promise to push the boundaries of the observable universe closer to cosmic dawn with the confirmation of a bright galaxy that existed ...
Astronomy
Jan 28, 2026
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442
What was the universe like in the first few hundreds of millions of years after it came into existence? How did the first stars and galaxies form? Those are questions that astronomers now have a better chance of answering, ...
Astronomy
Sep 1, 2025
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292
A new theoretical study by University of Virginia astrophysicist Jonathan Tan, a research professor with the College and Graduate School of Arts & Sciences' Department of Astronomy, proposes a comprehensive framework for ...
Astronomy
Aug 12, 2025
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