We have a new record! Astronomers have pushed the Hubble Space Telescope to the limit and uncovered a new galaxy so far away, it’s still in the process of formation only 400 million years after the universe began in the Big Bang. Located 13.4 billion light years from Earth, Yale researchers led an international team of astronomers to fish “GN-z11” from the dark. The previous record-holder, EGSY8p7, was found by astronomers using the giant Keck I telescope in Hawaii in 2015.
Its discoverers called the new galaxy, found in the constellation of the Great Bear (Ursa Major), “surprisingly bright”. The distance measurement of GN-z11 provides strong evidence that other unusually bright galaxies found in earlier Hubble images are really at extraordinary distances, showing that we’re closing in on the first galaxies that formed in the universe.
“We’ve taken a major step back in time, beyond what we’d ever expected to be able to do with Hubble. We see the galaxy at a time when the universe was only 3% of its current age, very close to the end of the so-called Dark Ages of the universe,” said Yale astronomer Pascal Oesch, the principal investigator.
The Dark Ages span the period from the Big Bang until the universe was about 400,000 years old. During this time, all matter existed as bare atomic nuclei and free-roaming electrons which formed a barrier to light, preventing it from traveling freely across space. If you’d been around then, all was darkness. But by 400,000 years, the cosmos had cooled enough for nuclei to grab electrons and form neutral atoms. Light was now free to travel across space, marking the end of the Dark Ages.
Astronomers determine an object’s distance by measuring its “redshift”. Because the universe is expanding, every distant object appears to be receding from us. When a sound is “stretched”, its pitch drops. When light get stretched, its waves get stretched to longer, redder wavelengths. The previous record distance holder, EGSY8p7, had a redshift of 8.68. Now, the team has confirmed GN-z11’s distance to be at a redshift of 11.1 (incorporated in the name), which corresponds to 400 million years after the Big Bang.
Moreover, the observations revealed the galaxy to be right at the distance limit of what Hubble can observe.
“The previous record-holder was seen in the middle of the epoch when starlight from primordial galaxies was beginning to heat and lift a fog of cold, hydrogen gas,” explained co-author Rychard Bouwens from the University of Leiden, the Netherlands in today’s press release. “This transitional period is known as the reionisation era. GN-z11 is observed 150 million years earlier, near the very beginning of this transition in the evolution of the universe.”
GN-z11 may be 25 times smaller than the Milky Way with just 1% of our galaxy’s mass in stars, but the number of stars in the newborn galaxy is growing fast: star formation proceeds at the blistering rate of 20 times that of the fuddy-duddy Milky Way. GN-z11 transforms about 24 solar masses of gas and dust per year into new stars. That’s a problem for astronomers because the existence of such a bright and large galaxy isn’t predicted by theory.
Zoom into the Big Dipper to see the cosmic distance breaker!
“It’s amazing that a galaxy so massive existed only 200 million to 300 million years after the very first stars started to form. It takes really fast growth, producing stars at a huge rate, to have formed a galaxy that is a billion solar masses so soon,” said Garth Illingworth of the University of California, Santa Cruz.
Don’t you love it when astronomers scratch their heads? Befuddlement lies at the root of knowledge.