Nearly the entire sky in the early universe is glowing with Lyman-alpha emission
MUSE spectrograph reveals uncovered vast cosmic reservoirs of atomic hydrogen
Date:
October 1, 2018
A universe aglow.
Credit: ESA/Hubble & NASA, ESO/ Lutz Wisotzki et al.
An unexpected abundance of Lyman-alpha emission in the Hubble Ultra Deep Field (HUDF) region was discovered by an international team of astronomers using the MUSE instrument on ESO's Very Large Telescope (VLT. The discovered emission covers nearly the entire field of view -- leading the team to extrapolate that almost all of the sky is invisibly glowing with Lyman-alpha emission from the early Universe [1].
Astronomers have long been accustomed to the sky looking wildly different at different wavelengths, but the extent of the observed Lyman-alpha emission was still surprising. "Realising that the whole sky glows in optical when observing the Lyman-alpha emission from distant clouds of hydrogen was a literally eye-opening surprise," explained Kasper Borello Schmidt, a member of the team of astronomers behind this result.
"This is a great discovery!" added team member Themiya Nanayakkara. "Next time you look at the moonless night sky and see the stars, imagine the unseen glow of hydrogen: the first building block of the universe, illuminating the whole night sky."
The HUDF region the team observed is an otherwise unremarkable area in the constellation of Fornax (the Furnace), which was famously mapped by the NASA/ESA Hubble Space Telescope in 2004, when Hubble spent more than 270 hours of precious observing time looking deeper than ever before into this region of space.
More:
https://www.sciencedaily.com/releases/2018/10/181001130348.htm
