WASHINGTON: Obse­rv­ations by Nasa’s James Webb Space Telescope are upending the understanding of the early universe, indicating the presence of large and mature but remarkably compact galaxies teeming with stars far sooner than scientists had considered possible.

Astronomers said data obtained by the telescope revealed what appear to be six big galaxies as mature as our Milky Way existing about 540 million to 770 million years after the explosive Big Bang that kicked off the universe 13.8 billion years ago.

The universe was roughly three per cent of its current age at the time.

These galaxies, one of which appears to have a mass rivalling our Milky Way but 30 times more densely packed, seem to differ in fundamental ways from those populating the universe today.

“Oh, they are 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 regular-sized average adult, say about 5’9” (1.75 metres) and 160 pounds (70 kg), these would be one-year-old babies weighing about the same but standing just under three inches (seven centimetres) tall. The early universe is a freak show.”

Webb was launched in 2021 and began collecting data last year. The findings were based upon the first dataset released by Nasa in July from Webb, a telescope boasting infrared-sensing instruments able to detect light from the most ancient stars and galaxies.

“This is an astounding discovery and unexpected. We thought that galaxies form over much longer periods of time,” said Penn State astrophysicist and study co-author Joel Leja.

“No one expected to find these. These galaxy candidates are simply too evolved for our expectations. They seem to have evolved faster than allowed by our standard models.”

Galaxy candidates

Leja called them galaxy candidates because further observations are needed to confirm that they all are galaxies rather than some other source of light like a supermassive black hole.

“The exciting part is that even if only some turn out to be massive galaxies, these things are so massive that they alone would upend our measurements of the total mass in stars at this time. It would suggest 10 to 100 times more mass in stars existing at this epoch than expected and would imply that galaxies form way, way faster in the universe than anyone thought.”

The galaxies appear to contain mass equivalent to 10 billion to 100 billion times that of our sun. The latter figure is similar to the Milky Way’s mass.

The journey to galaxy formation following the Big Bang apparently hinged on mysterious material called dark matter that is invisible to us, but is known to exist because of the gravitational influence it exerts on normal matter.

“The leading theory is that an ocean of dark matter filled the early universe after the Big Bang,” Labbe said.

Published in Dawn, February 23rd, 2023