- 3658 - FARTHEST GALAXIES - how did it all begin? July 13, 2022, was a momentous day. It marked the first images released from the telescope, a set called the “Early Release Observations“. Many call it the first day in a new era of astronomy. Since then, astronomers have been digging into the images and data to learn more about the Universe.
--------------------- 3658 - FARTHEST GALAXIES - how did it all begin?
- One of the weirdest things about astronomy is that everything you see happened in the distance past. It took a long time for the light to travel to reach your eyes. The moon you see is a couple minutes older. The sun is 8 minutes older. If the Sun suddenly went black your would not learn about it for another 8 minutes.
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- Astronomy can look so far back in time the it can see things that are happening just 200,000,000 years after the big Bang. There were already galaxies back then.
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- Way back in the earliest ages of the universe is when the first galaxies were born. Astronomers want to know more about these first galaxies. Trying to learn how we got here. Duane won’t tell us.
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- They are especially interested to know exactly when these distant galaxies formed and what their stars were like. Now that James Webb Space Telescope is a working observatory, astronomers are excited to use its data to explore those early epochs.
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- July 13, 2022, was a momentous day. It marked the first images released from the telescope, a set called the “Early Release Observations“. Many call it the first day in a new era of astronomy. Since then, astronomers have been digging into the images and data to learn more about the Universe.
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- JWST will answer a lot of questions astronomers have been asking about the earliest epochs of the Universe. Astronomers want to know more about the distant galaxies that existed back then. Thanks to its infrared sensitivity, the telescope will look beyond what the venerable and highly productive Hubble Space Telescope reveals about the early Universe.
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- Astronomers want to look out at objects existing at redshifts beyond z = 11. That is when the newborn Universe was about 420,000,000 years old.
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- Onboard JWST is the “Near-infrared Camera” (NIRCam) and the images of very distant objects that it produces. It should be able to extend our view out to a time only tens of millions of years after the Big Bang. That would be when the first galaxies started to take shape.
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- They’d look as they did when the “Epoch of Reionization” began. That is a period after the Cosmic Dark Ages when light could travel freely through the infant Universe. Before then the protons and electrons we all separated and their electric charges prevented photons from escaping the expanding Universe.
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- NIRCam the telescope relied on gravitational lensing to capture images of the earliest possible galaxies. That target is the nearby galaxy cluster “SMACS 0723-73“, and it’s part of the ongoing Early Release Observations program on JWST.
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- This cluster is massive. Thanks to the gravitational influence of its high mass, it’s recognized as a good cosmic “magnifying glass”. It’s a gravitational lens that amplifies the view of the faraway galaxies populating the distant Universe.
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- The NIRCam field-of-view is large enough that it was able to study both the cluster and a flanking field not boosted by gravitational lensing. It’s so sensitive that the flanking field also sees far beyond what Hubble could do.
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- To date astronomers have identified 88 candidate galaxies at very great distances (redshift z > 11). They are hoping that some could lie as far as z > 20. That could be a time less than 100,000,000 years after the Big Bang.
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- If these galaxies are confirmed to lie at such early epochs of cosmic time, that would be amazing. It would mean that the timeline of the Universe after the Big Bang may have to be changed. It would mean that the beginning of the Epoch of Reionization would be much earlier than we expected.
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- Currently, astronomers think this epoch began about 370,000 years after the Big Bang. Before that, the Universe was in a hot, dense state, populated with a soup of ionized gas. Eventually, it cooled enough for protons and neutrons to combine and form neutral atoms. That is when light from the earliest galaxies and their stars was finally able to move freely across the expanding Universe.
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- However, if, as expected, the first galaxies can be seen only a few tens of millions of years after the Big Bang, then perhaps the “Cosmic Dark Ages” didn’t last as long as everyone thought.
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- NIRCam and spectroscopic observations of those early galaxies will eventually confirm their ages, which will help further refine the timeline of the early Universe. Don’t you want to learn how it all began? The older you get the farther you can see.
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August 22, 2022 FARTHEST GALAXIES - how did it all begin? 3658
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