Monday, March 13, 2023

3916 - OLDEST GALAXY - did James Webb find it?

 

-   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?

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-   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.

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-   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.

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-    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.

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-   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. 

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-    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.

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-    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.

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-   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.

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-   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.

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-  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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--------------------- ---  Monday, March 13, 2023  ---------------------------

 

 

 

 

         

 

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