How EGS77, the most distant galaxy ever to be identified, helped us see the night sky
A team of astronauts have spotted the most distant galaxy group ever — EGS77. This galaxy group was responsible for giving our universe a makeover, helping it transition from a dark, cloudy one to a transparent universe we see today, says a new study.
"This is the first time we have seen a group of galaxies responsible for this transition," Dr Vithal Tilvi, a researcher at Arizona State University in Tempe and the lead author of the study told MEA WorldWide (MEAWW). "Soon after the Big Bang, the universe was completely covered with fog made of hydrogen atoms. Because of this fog, the universe was opaque. But after some time, the universe became nearly completely transparent to all starlight," he explains.
And EGS77 is the first galaxy group caught in the act of clearing out this cosmic fog, says James Rhoads at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, who presented the findings on January 5 at the 235th meeting of the American Astronomical Society in Honolulu.
Three galaxies make up the EGS77 galaxy group. According to a statement from NASA, the galaxy group dates back to a time when the universe was only 680 million years old, or less than 5% of its current age of 13.8 billion years.
Astronomers have not been able to track this galaxy group until now, thanks to its distance: it is 13.8 billion light-years away, the farthest galaxy to be discovered to date. This means we are viewing what EGS77 looked like about 13 billion years ago, as the starlight carrying information about that part of the universe took over 13 billion years to reach us.
Back then, the universe was young. In its earliest phase, the universe was filled with electrons, protons, atomic nuclei, and light — but no atoms. After this, the universe expanded and cooled for about 380,000 years, creating the first atoms — with more than 90% of them being hydrogen. Hundreds of millions of years later, the hydrogen gas formed the first stars and galaxies. The same gas also poses challenges for spotting galaxies in the early universe, as it appeared opaque and dense.
The galaxy group, however, managed to clear its environment shrouded in gas. "Intense starlight coming from the earliest galaxies or groups like EGS77 helped clear the fog, which had a lasting impact on how the universe evolved, leading to cosmic makeover," Dr Tilvi told MEAWW.
Tilvi and team now hope to discover more galaxies like EGS77 through the upcoming James Webb Space Telescope, which is scheduled for launch in 2021. He tells MEAWW, "We have successfully shown that using special techniques, we can still do frontier research to advance the knowledge of how the universe evolved from almost nothing to what we see today."
The study has been submitted to The Astrophysical Journal.