- 3931 - GALAXIES - oldest and farthest? Astronomers pin down the age of the most distant galaxy seen 367 Million years after the Big Bang. The James Webb Space Telescope (JWST) was built to peer back in time and identify the Universe’s very first galaxies.
------------ 3931 - GALAXIES - oldest and farthest?
- Those James
Webb 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
-
- 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 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 early galaxies.
-
- Astronomers
set out decades ago to build the JWST with these findings in mind. 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.
-
- A team of
researchers used the ESO’s ALMA (Atacama Large Millimetre/sub-millimetre Array)
to examine a candidate galaxy from GLASS and to try to confirm it. Their paper
is titled “Deep ALMA redshift search of a z = 12 , GLASS-JWST galaxy
candidate”.
-
- 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.
-
- A galaxy
named GHZ2/GLASS-z12, 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 travelling 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. The 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. Focusing
on oxygen increased the likelihood of detection.
-
- Stars can
generate oxygen on a short 50 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?
-
- Hubble Space
Telescope’s Deep Field revealed thousands of galaxies in a seemingly empty spot
in the sky. Now, the James Webb Space Telescope has taken deep field
observations to the next level with its COSMOS-Web survey, revealing 25,000
galaxies in just six pictures, the first from this new survey.
-
- The first
images to be released from the survey accounts for just 4% of the data that
will eventually be collected with COSMOS-Web. The images show many types of
galaxies, including spiral galaxies, examples of gravitational lensing, and
evidence of galaxy mergers.
-
- JWST’s
first year and the goal of the survey is to map the earliest structures of the
universe, as well as create a deep survey of up to 1 million galaxies. With a
total of 255 hours of observing time, COSMOS-Web will map 0.6 square degrees of
the sky with NIRCam, roughly the size of three full moons, and 0.2 square
degrees with MIRI.
-
- While the
Hubble Deep Field imagers were stunning, these new images from JWST contain
details that are inaccessible to Hubble.
Basically, everywhere ever we look, it’s a Deep Field. These engineering
images are as sharp and crisp as images that Hubble can take, but at a
wavelength of light that Hubble can’t see.
-
- The goal of
COSMOS-Web is to map the earliest structures of the universe and create a wide
and deep survey of up to 1 million galaxies. The survey hopes to map cosmic
reionization, study galaxy evolution and determine if dark matter can be linked
to visible matter.
-
- Over the
course of 255 hours of observing time, COSMOS-Web will map 0.6 square degrees
of the sky with NIRCam, roughly the size of three full moons, and 0.2 square
degrees with MIRI. (as of March, 2023)
-
- This first
snapshot of COSMOS-Web contains about 25,000 galaxies—an astonishing number
larger than even what sits in the Hubble Ultra Deep Field. It’s one of the largest JWST images taken
so far. And yet it’s just 4 percent of the data we will get for the full
survey.
-
- The first
epoch of COSMOS-Web MIRI observations obtained on January 6, 2023. What were thought to be compact objects
based on the best images we had so far, the JWST observations are now able to
resolve these objects into multiple components, and in some cases even reveal
the complex morphology of these extragalactic sources.
-
- With these
first observations, we have just barely scratched the surface of what is to
come with the completion of this program, next year.”
-
March 26, 2023 GALAXIES -
oldest and farthest?
3931
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--- Monday, March 27, 2023 ---------------------------
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