From Afar In Space And Time Ancient Galaxy Rattles Early Universe Science

The most distant galaxy and one of universe's oldest, is shaking the foundation of established theories that explain early years of cosmos after Big Bang.

Scientists at California Institute of Technology (CALTECH) first spotted the galaxy EGS8p7 earlier this year using the NASA Hubble and Spitzer Space Telescopes. They knew they were peering at an ancient galaxy deep in space and time. When they examined the light from stars of EGS8p7 using the MOSFIRE spectrometer on Hawaii Island, they concluded that it is 13.2 billion years old. The universe is said to be 13.8 billion years.

The galaxy's age was estimated by determining what is called the redshift in light. Farther the galaxy, greater the redshift parameter associated with light from its stars. The spectrometer estimated a redshift of 8.68 for EGS8p7. The farthest known galaxy before the recent discovery has a redshift of 7.73.

"We are currently calculating more thoroughly the exact chances of finding this galaxy and seeing this emission from it, and to understand whether we need to revise the timeline of the reionization, which is one of the major key questions to answer in our understanding of the evolution of the universe," said study author Adi Zitrin in a Caltech press release.

EGS8p7 dates to a time when the universe was just entering a phase of reionization following cooling and formation of hydrogen, when it was about half billion years old. The kind of radiation that helped researchers detect the distant galaxy should have been theoretically absorbed by hydrogen before reionization happened.

"If you look at the galaxies in the early universe, there is a lot of neutral hydrogen that is not transparent to this emission. We expect that most of the radiation from this galaxy would be absorbed by the hydrogen in the intervening space. Yet still we see Lyman-alpha [the characteristic radiation] from this galaxy," Zitrin said.

This has led the team to conclude that the so-called reionization process was patchy and not uniform as was thought.