- 3916 - OLDEST GALAXY - did James Webb find it? What is the oldest galaxy? Astronomers pin down the age of the most distant Galaxy and what we see occurred 367 Million Years After the Big Bang, or over 360 billion years ago.
------------ 3916 - OLDEST GALAXY - did James Webb find it?
- Staring off
into the ancient past with a $10,000,000 space telescope the James Webb has
found those signals 360,000,000,000 years away. JWST was specifically built to peer back in
time and identify the Universe’s very first galaxies.
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- Those
observations are meant to forge a link between the ancient galaxies and the
galaxies we see now, including our own. That link will help astronomers
understand how galaxies like ours formed and evolved over billions of
years. How did it all get started?
-
- The
expansion of the Universe stretches the light emitted by ancient objects
billions of years ago. The stretching shifts the light toward the red end of
the visible light spectrum. The James Webb Space Telescope was built to see
this infrared light and identify the ancient galaxies that emitted it.
-
- The
telescope’s “GLASS Survey” used the galaxy cluster called Pandora’s Cluster
(Abell 2744) as a gravitational lens to magnify distant galaxies behind it and
found 19 bright objects that appear to be very early galaxies.
-
- But there’s
a problem: our theories and models of galaxy formation suggest there shouldn’t
be so many of these earliest galaxies. The JWST’s findings needed to be
confirmed.
-
- So they used
the ESO’s ALMA (Atacama Large Millimetre/sub-millimetre Array) to examine a
candidate galaxy from GLASS and to try to confirm it. If all of these ultra-distant galaxy
candidates were real, we’d have too many of them too early, forcing us to
rethink how galaxies begin forming within the Universe.
-
- There’s a
tremendous difference between the light that a distant galaxy emits and the
light that arrives at our eyes after journeying for billions of light-years
across the Universe.
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- More
observations were needed to confirm any of these ancient candidates. The galaxy named “GHZ2/GLASS-z12”, is one of
the brightest and most robust candidates at z > 10, according to the JWST
observations.
-
- z > 10
means that the light from the galaxy has been traveling for over 13.184 billion
years and has traveled a distance of at least 26.596 billion light-years.
-
- Spectroscopy
is needed to confirm the primeval nature of these candidates. It’s possible that the light from some of
these galaxies is red due to dust rather than distance, and spectroscopy could
help differentiate between the two. Astronomers turned to ALMA, the world’s
most expensive ground-based telescope currently operating.
-
- They used it
to look for an oxygen line (O III) in the spectroscopy at the same frequency
found in the JWST observations. O III is doubly-ionized oxygen, and it’s key
because oxygen has a short formation time relative to other elements.
-
- Stars can
generate oxygen on a short 50 million year (Myr) time scale. Other elements,
like carbon, for example, take nearly 500 Myr to appear in a galaxy. This means
that oxygen is generally the best redshift indicator. and is likely the
brightest emission line in the early Universe. Could ALMA find it? Will let you
know what we learn.
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March 13, 2023 OLDEST
GALAXY - did James Webb find it? 3916
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