- 3644 - GALAXY - most distant galaxy? The most distant phenomenon observed is the “cosmic microwave background” (CMB) which is the ‘afterglow’ of the Big Bang. The light from the CMB comes from approximately 400,000 years after the Big Bang and has been observed by various instruments over the years, most notably the Planck satellite which launched in 2009.
--------------------- 3644 - GALAXY - most distant galaxy?
- The James Webb Space Telescope (JWST) discovering a galaxy, ‘CEERS-93316‘, that formed approximately 250 million years after the Bing Bang. This set a new redshift record of z = 16.7.
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- CEERS stands for Cosmic Evolution Early Release Science Survey, and was specifically created for imaging with JWST.
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- It is important to note that to be certain of the redshift, the galaxy will need follow up observations using spectroscopy. The study determined that CEERS-93316 can’t be a low-mass star or unobstructed active galactic nucleus based on imaging data from NIRCam (Near Infrared Camera), which is JWST’s primary imager.
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- After the Big Bang the Universe entered a period known as the “dark ages“, a time before any stars had been born. The observations of this galaxy push observations back to the time when we think the first galaxies ever to exist were being formed.
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- Given this incredible finding in just the first set of data from JWST, it’s intriguing to think how much father back in the universe this record-shattering space telescope can see.
In principle JWST can detect galaxies at redshifts greater than 20, less than 200,000,000 years after the Big Bang.
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- Redshift is part of what’s known as the Doppler effect, which astronomers use to measure distances in the universe. A frequent example to demonstrate the Doppler effect is the change in sound wave pitch as a loud object travels towards you then travels away from you, often by an ambulance or other first responder vehicle. The sound waves as the object travels towards you is known as blueshift, while the opposite is called redshift.
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- This new study setting a new redshift record, z = 16.7, means scientists have measured the farthest object in the universe to date.
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- Although the particles of dark matter continue to allude astronomers they continue to find evidence of it. In a recent study, they have seen its effect from the edge of visible space, when the universe was just 1.5 billion years old.
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- Dark matter doesn’t emit its own light, nor does it absorb light like a dark cloud. But it does affect light gravitationally. So clumps of dark matter create a gravitational lens that deflects and focuses light. Astronomers have long used this effect to map dark matter within galactic clusters.
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- You can even see this “lensing effect” in the recent Webb deep field images. The light from more distant galaxies is warped by the mass of closer galaxies, which astronomers can map to calculate the distribution of dark matter in those closer galaxies.
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- In this latest study, the galaxies are so distant that there aren’t really any more distant galaxies. Certainly none bright enough that we can see their lensed light. So instead, the team used the light from the cosmic microwave background (CMB).
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- To map dark matter, they used data from the “Subaru Hyper Suprime-Cam Survey” (HSC), and identified about 1.5 million faint and distant galaxies. They then used data from the “Plank satellite” to see how CMB light was deflected. From this, they created a map of dark matter in the early universe.
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- The most distant measure of dark matter opens a possible crack in our current model of the universe. In the standard cosmological model, known as the “LCDM model“, dark energy drives the expansion of the universe, striving to push galaxies apart, while the gravitational attraction of matter and dark matter cause galaxies to clump together.
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- According to LCDM, the scale at which we observe fluctuations in the cosmic background drives the scale at which galaxies cluster together, which tells us how densely galaxies should be clustered in the early universe. The amount of galactic clustering in the early period is slightly less than predicted by the LCDM model.
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- The uncertainty of these measurements means their result isn’t conclusive. It’s possible that they simply under measured the clumping scale. But if it’s right, it suggests that the laws of the universe were a bit different 12 billion years ago.
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- There are a lot of possibilities. But the biggest success of this work is that we now have actual data. It’s a big first step, and as we get more data from telescopes such as the James Webb Space Telescope and Vera Rubin Observatory, we should be able to solve this mystery, and finally learn if the cosmic laws really were different in the dark and distant past.
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August 7, 2022 GALAXY - most distant galaxy? 3631
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