Oct. 1 (UPI) -- Astronomers have discovered an abundance of Lyman-alpha radiation in Hubble Ultra-Deep Field.
The data -- collected by the MUSE spectrograph on ESO's Very Large Telescope -- suggests the universe's earliest galaxies were surrounded by large reservoirs of hydrogen.
The Hubble Ultra-Deep Field is a small, dark region of the night sky home to a large concentration of ancient galaxies. The field is home to thousands of the cosmos' earliest galaxies, as they appeared just a few hundred million years after the Big Bang. The field's light spent 12 billion years traveling to Hubble's lens.
Lyman-alpha emission, or radiation, is the spectral line of hydrogen. As revealed by the spectrographic data collected by MUSE, the early universe was saturated by Lyman-alpha emission.
"Realizing that the whole sky glows in optical when observing the Lyman-alpha emission from distant clouds of hydrogen was a literally eye-opening surprise," astronomer Kasper Borello Schmidt said in a news release.
The MUSE spectrograph is installed on VLT's Unit Telescope 4 at the European Southern Observatory's Paranal Observatory, located in northern Chile's Atacama Desert. MUSE's sensors record the entire spectrum of light, offering astronomers a deep and detailed view of the ancient universe.
"With these MUSE observations, we get a completely new view on the diffuse gas 'cocoons' that surround galaxies in the early Universe," said researcher Philipp Richter.
Astronomers described their discovery of the ubiquitous Lyman-alpha emission in HUDF this week in the journal Nature.
Scientists still aren't sure what causes hydrogen to emit Lyman-alpha radiation, but are hopeful future analysis of galaxies in HUDF will reveal the mechanism.
"In the future, we plan to make even more sensitive measurements," researcher Lutz Wisotzki said. "We want to find out the details of how these vast cosmic reservoirs of atomic hydrogen are distributed in space."