Scientists have discovered a 13.2 billion-years old farthest known galaxy named EGS8p7.
Sirio Belli of California Institute of Technology (Caltech) said, “The galaxy we have observed is named EGS8p7, is unusually luminous and may be powered by a population of unusually hot stars.”
She said the new galaxy may have special properties that enabled it to create a large bubble of ionised hydrogen much earlier than is possible for more typical galaxies.
After the Big Bang, when the universe was just a half-billion to a billion years old, the first galaxies turned on and reionised the neutral gas. Hence, the universe remains ionised today, she explained.
Prior to reionization clouds of neutral hydrogen atoms would have absorbed radiation from newly forming galaxies–including Lyman-alpha line, which features hot hydrogen gas that has been heated by ultraviolet emission from new stars, and a commonly used indicator of star formation.
This could have made it difficult to observe a Lyman-alpha line from EGS8p7. “If you look at the galaxies in the early universe, there is a lot of neutral hydrogen that is not transparent to this emission,” said Adi Zitrin, NASA Hubble researcher.
The present discovery of this Lyman-alpha line in an apparently faint galaxy, corresponding to a time when the universe should be full of absorbing hydrogen clouds is notable, said Richard Ellis, another astro-physicist who recently retired from the Caltech.
The team is excited to have found the farthest galaxy and is exploring more thoroughly the exact chances of finding this galaxy and the need to revise the timeline of the reionisation.
“Reionisation is one of the major key questions to answer in our understanding of the evolution of the universe,” Zitrin said in the paper published in Astrophysical Journal Letters.