Saturday, February 25, 2023

3886 - EARLIEST GALAXIES - did JWST find them?

 

-  3886  -    EARLIEST  GALAXIES  -  did JWST find them?     The James Webb Space Telescope has discovered a group of galaxies from the dawn of the universe that are so massive they shouldn't exist.  The six gargantuan galaxies contain almost as many stars as the Milky Way despite forming only 500 to 700 million years after the Big Bang.


------------  3886 -   EARLIEST  GALAXIES  -  did JWST find them?

-  If these early galaxies are real, the discovery calls our entire understanding of galaxy formation into question.  You just don't expect the early universe to be able to organize itself that quickly. These galaxies should not have had time to form.

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-   Cosmologists previously estimated that the process began slowly taking shape within the first few hundred million years after the Big Bang. Currently accepted theories suggest that 1 to 2 billion years into the universe's life, these early protogalaxies reached adolescence forming into dwarf galaxies that began devouring each other to grow into ones like our own Milky Way Galaxy.

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-   Because light travels at a fixed speed through the vacuum of space, the deeper we look into the universe, the more remote light we intercept and the further back in time we see. By using the James Webb Space Telescope (JWST) to peer roughly 13.5 billion years into the past, the astronomers found that enormous galaxies had already burst into life very quickly after the Big Bang, when the universe was just 3% of its current age.

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-    The galaxies are so massive that either the models need to be altered, or scientific understanding of galaxy formation requires a fundamental rethink. The Milky Way forms about one to two new stars every year.  Some of these galaxies would have to be forming hundreds of new stars a year for the entire history of the universe.

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-    Right now, all evidence points to these celestial objects being galaxies, but the astronomers haven't ruled out that some of them could be enormous quasars or supermassive black holes.  This is our first glimpse back this far, so it's important that we keep an open mind about what we are seeing.  

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-    While the data indicates they are likely galaxies, I think there is a real possibility that a few of these objects turn out to be obscured supermassive black holes. Regardless, the amount of mass we discovered means that the known mass in stars at this period of our universe is up to 100 times greater than we had previously thought.

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-   The $10 billion JWST launched to a gravitationally stable location beyond the moon's orbit, a Lagrange point, in December 2021. The space observatory was designed to read the earliest chapters of the universe's history in its faintest glimmers of light, which have been stretched to infrared frequencies from billions of years of travel across the expanding fabric of space-time.

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-     Staring off into the ancient past with a $10 billion space telescope, wqith hope to find extraordinarily faint signals from the earliest galaxies.  The James Webb Space Telescope was built to peer back in time and identify the Universe’s very first galaxies.

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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 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 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.  The ESO’s ALMA (Atacama Large Millimetre/sub-millimetre Array) will 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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-   Galaxy named “GHZ2/GLASS-z12”, one of the brightest and most robust candidates at z > 10.   “ z > 10” means that the light from the galaxy has been travelling for over 13.184 billion years and has travelled 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 Myr time scale. Other elements, like carbon 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?

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            February 23, 2023       EARLIEST  GALAXIES  -  did JWST find them?     3886                                                                                                                          

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--------------------- ---  Saturday, February 25, 2023  ---------------------------

 

 

 

 

         

 

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