Galaxies spotted by Webb telescope rewrite understanding of early
universe
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[February 23, 2023]
By Will Dunham
WASHINGTON (Reuters) - 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 reveals 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 3% of
its current age at the time.
These galaxies, one of which appears to have a mass rivaling 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 Swinburne University of Technology in
Australia, 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
meters) and 160 pounds (70 kg), these would be 1-year-old babies
weighing about the same but standing just under 3 inches (7 cm) 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 last 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."
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."
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Images of six candidate massive
galaxies, seen 540 million to 770 million years after the Big Bang,
are shown in this undated handout image based on observations by
NASA's James Webb Space Telescope, as one of them (bottom left)
could contain as many stars as our present-day Milky Way, but is 30
times more compact. NASA, ESA, CSA, I. Labbe (Swinburne University
of Technology)/Handout via REUTERS
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.
"This dark matter - we don't know what it is actually is - started
out really smooth, with only the tiniest of ripples. These ripples
grew over time due to gravity and eventually the dark matter started
to collect in concentrated clumps, dragging hydrogen gas along for
the ride. It's that hydrogen gas that will eventually turn into
stars. Clumps of dark matter, gas and stars is what we call a
galaxy," Labbe added.
Astronomers suspect the first stars began forming 100 million to 200
million years after the Big Bang, each perhaps 1,000 more massive
than our sun but much shorter-lived.
"Their explosion set off the chain of events that formed subsequent
generations of stars," Labbe said.
"Webb continuous to amaze and surprise us," Labbe added. "So yes,
the early universe was a lot richer and lot more diverse - monsters
and dragons. And the curtain is still being lifted."
(Reporting by Will Dunham, Editing by Rosalba O'Brien)
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