- 4615 - COSMIC EXPANSION – zigzags in space time?- A new James Webb space telescope study has revealed the true origins of a luminous quasar that has been duplicated six times as its light "zig-zags" through space-time via a phenomenon first predicted by Albert Einstein. The unusual light show could help tackle one of cosmology's biggest problem.
----------------------------------- 4615 - COSMIC EXPANSION – zigzags in space time?
- Researchers discovered the "Einstein
zig-zag" phenomenon while analyzing six mirror images of a single
gravitationally lensed quasar in the distant cosmos. Image data from the James Webb Space
Telescope (JWST) to uncover an example of a previously hypothetical phenomenon
known as an "Einstein zig-zag" where light from an object in the
distant cosmos passes through two different regions of warped space-time.
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- The newly confirmed effect, which was
discovered among six identical copies of a luminous quasar, could shed light on
an issue that is beginning to plague cosmology. In 2018, astronomers discovered a quartet
of identical bright points billions of light-years from Earth, later named
J1721+8842.
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- Initially, the scientists assumed that the
four lights were mirror images of a single quasar, a luminous galactic core
powered by a feeding black hole, that had been duplicated through a phenomenon
known as "gravitational lensing."
-
- Gravitational lensing happens when light
from a distant object appears to get bent as it passes through warped
space-time that has been pulled out of shape by the immense gravity of a
lensing object, usually a massive galaxy or cluster of galaxies, located
between the distant object and the observer.
-
- This warping effect can either duplicate
the initial light source, as the light takes different routes around the
lensing object, or stretch out the light into luminous halos, known as Einstein
rings after Albert Einstein, who first predicted gravitational lensing with his
theory of general relativity in 1915.
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- In the 2022 study, researchers discovered
that J1721+8842 had two additional points of light alongside the original
quartet, as well as a faint red Einstein ring. The newly discovered points were
slightly fainter than the other four points, which led researchers to suspect
that the light show showed a pair of adjacent quasars, known as a binary
quasar, that had been duplicated three times rather than a single quasar that
had been copied six times.
-
- Light from Einstein rings and other
gravitationally lensed objects appears to bend around their lensing objects.
But in reality, the light is travelling in a straight line through warped
space-time.
-
- Researchers reanalyzed J1721+8842 using new
data from JWST and found that all six points of light are actually from a
single quasar after all. The team also found that newly unveiled bright spots
have been lensed around a second massive object farther away from the first,
which is also responsible for the faint Einstein ring seen in more recent
images.
-
- After observing the light curves of each
bright spot over two years, researchers showed that there is a slight delay in
the time it takes the two faintest duplicate images to reach us, which suggests
that the light in these copies has to travel farther than the other four bright
spots. This is likely because the light in these images passes around the
opposite sides of each lensing object (i.e. around the left side of the first
lens and right side of the second lens).
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- The study team has named this
"extremely rare lensing configuration" an Einstein zig-zag because
light from some of the double-lensed bright spots has swerved back and forth as
it passed around both lensing galaxies.
-
- Gravitationally lensed objects, such as
Einstein rings, are treasured by astronomers and cosmologists because the
warped light can help reveal the mass of the galaxies that lensed them. This,
in turn, can help reveal secrets of the universe such as the secret identity of
dark matter and how dark energy drives cosmic expansion.
-
- JWST has been exceptionally good at finding
these objects in parts of the universe where we have never been able to see
them before. But unfortunately, the state-of-the-art telescope has also
highlighted discrepancies we cannot currently explain.
-
- For example, measurements from the telescope
have confirmed that different parts of the universe are expanding at different
rates, which threatens to "break" our understanding of cosmology.
Researchers refer to this problem as the “Hubble tension”.
-
- However, researchers believe that the newly
confirmed Einstein zig-zag could help to smooth out this tension because its
unique configuration will allow astronomers to precisely measure both the
Hubble constant — the rate at which cosmic expansion is accelerating — and the
amount of dark energy — the invisible force driving the universe's expansion —
in this region of space.
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-
November 21, 2024 COSMIC EXPANSION –
zigzags in space time? 4615
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--------------------- --- Thursday, November 21,
2024
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