Astronomers discover metal-rich galaxies in early universe

Date:
February 27, 2023
Source:
Cornell University
Summary:
While analyzing data from the first images of a well-known
early galaxy taken by NASA's James Webb Space Telescope (JWST),
astronomers discovered a companion galaxy previously hidden behind
the light of the foreground galaxy -- one that surprisingly seems
to have already hosted multiple generations of stars despite its
young age, estimated at 1.4 billion years old.


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FULL STORY ========================================================================== While analyzing data from the first images of a well-known early galaxy
taken by NASA's James Webb Space Telescope (JWST), Cornell University astronomers discovered a companion galaxy previously hidden behind the
light of the foreground galaxy -- one that surprisingly seems to have
already hosted multiple generations of stars despite its young age,
estimated at 1.4 billion years old.


==========================================================================
"We found this galaxy to be super-chemically abundant, something none of
us expected," said Bo Peng, a doctoral student in astronomy, who led the
data analysis. "JWST changes the way we view this system and opens up new venues to study how stars and galaxies formed in the early universe."
Peng is the lead author of "Discovery of a Dusty, Chemically Mature
Companion to z~4 Starburst Galaxy in JWST Early Release Science Data," published in theAstrophysical Journal Letters.

Earlier images captured by the Atacama Large Millimeter/submillimeter
Array (ALMA) in Chile contained hints of the companion resolved clearly
by JSWT, but couldn't be interpreted as anything more than random noise,
said Amit Vishwas, a research associate at the Cornell Center for
Astrophysics and Planetary Sciences (CCAPS) and the paper's second author.

The team estimated the companion galaxy, which they labeled SPT0418-SE,
was within 5 kiloparsecs of SPT0418-47, one of the brightest dusty, star-forming galaxies in the early universe, its distant light bent
and magnified by a foreground galaxy's gravity into a circle, called an Einstein ring. The Magellanic Clouds, satellites of the Milky Way are
about 50 kiloparsecs away.

The proximity suggests these galaxies are bound to interact with each
other and potentially even merge, an observation that adds to the
understanding of how early galaxies may have evolved into larger ones.

The two galaxies are modest in mass as galaxies in the early universe go,
with "SE" relatively smaller and less dusty, making it appear bluer than
the extremely dust-obscured ring. Based on images of nearby galaxies
with similar colors, the researchers suggest that they may reside
"in a massive dark-matter halo with yet-to-be-discovered neighbors."
Most surprising about the companion galaxy, considering its age and mass,
was its mature metallicity -- amounts of elements heavier than helium
and hydrogen, such as carbon, oxygen and nitrogen. The team estimated
that as comparable to our sun, which is more than 4 billion years old
and inherited most of its metals from previous generations of stars that
had 8 billion years to build them up.

"We are seeing the leftovers of at least a couple of generations of
stars having lived and died within the first billion years of the
universe's existence, which is not what we typically see," Vishwas
said. "We speculate that the process of forming stars in these galaxies
must have been very efficient and started very early in the universe, particularly to explain the measured abundance of nitrogen relative to
oxygen, as this ratio is a reliable measure of how many generations of
stars have lived and died."
* RELATED_TOPICS
o Space_&_Time
# Galaxies # Astrophysics # Stars # Astronomy # Cosmology
# Big_Bang # Solar_System # Nebulae
* RELATED_TERMS
o Spitzer_space_telescope o Andromeda_Galaxy o
Barred_spiral_galaxy o Milky_Way o Globular_cluster o Galaxy
o Planetary_nebula o Large-scale_structure_of_the_cosmos

========================================================================== Story Source: Materials provided by Cornell_University. Original written
by James Dean, courtesy of the Cornell Chronicle. Note: Content may be
edited for style and length.


========================================================================== Journal Reference:
1. Bo Peng, Amit Vishwas, Gordon Stacey, Thomas Nikola, Cody Lamarche,
Christopher Rooney, Catie Ball, Carl Ferkinhoff, Henrik
Spoon. Discovery of a Dusty, Chemically Mature Companion to a z ~
4 Starburst Galaxy in JWST ERS Data. The Astrophysical Journal
Letters, 2023; 944 (2): L36 DOI: 10.3847/2041-8213/acb59c ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2023/02/230227161428.htm

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