Observations by NASA’s James Webb Space Telescope are advancing our understanding of the early universe, pointing to the presence of large and mature but remarkably compact galaxies teeming with stars much earlier than scientists thought possible.
Astronomers said data obtained by the telescope revealed what appear to be six large galaxies as mature as our own Milky Way existing some 540 million to 770 million years after the explosive Big Bang that started the universe 13.8 billion years ago. At that time, the universe was roughly three percent of its current age.
These galaxies, one of which has a mass rivaling that of our Milky Way but packed 30 times more densely, appear to be fundamentally different from those that populate the universe today.
“Oh, they’re radically different – truly bizarre creatures,” said astrophysicist Ivo Labbe of Australia’s Swinburne University of Technology, lead author of the study published in the journal Nature. “If the Milky Way were a normal average adult, say about 5’9” (1.75 meters) and 160 pounds (70 kg), they would be one-year-old babies weighing about the same but standing just under three inches tall. (seven centimeters) tall. The early universe is a freak show.’
Webb launched in 2021 and began collecting data last year. The findings were based on the first dataset released by NASA in July from Webb, a telescope that boasts infrared sensors capable of detecting light from the oldest stars and galaxies.
“It’s a stunning and unexpected discovery.” We thought that galaxies form over much longer timescales,” said Penn State astrophysicist and study co-author Joel Leja.
“No one expected to find them. These galaxy candidates are simply too evolved for our expectations. They seem to have evolved faster than our standard models allow.”
Candidates for the Galaxy
Leia called them candidate galaxies because more observations are needed to confirm that they are all galaxies rather than some other source of light, such as a supermassive black hole.
“The exciting thing is that even if only a few turn out to be massive galaxies, these things are so massive that they would by themselves overturn our measurements of the total mass in stars at this point in time. This would indicate 10 to 100 times more mass in stars existing in this epoch than expected, and would mean that galaxies are forming much faster in the universe than anyone thought.
Galaxies appear to contain mass equivalent to 10 billion to 100 billion times the mass of our Sun. The last figure is similar to the mass of the Milky Way. The path to galaxy formation after the Big Bang appears to have depended on a mysterious material called dark matter, which is invisible to us but known to exist due to the gravitational influence it has on normal matter. “The leading theory is that an ocean of dark matter filled the early universe after the Big Bang,” Labbe said.
