- 3917 - GRAVITY LENS - create multiple images? Astronomers have measured a time delay of 6.73 years, the longest ever detected for a gravitational lens, between multiple images of a quasar. The result, obtained after 14.5 years of observation. This finding will improve our knowledge about galaxy clusters and the dark matter they contain.
------------ 3917 - GRAVITY LENS - create multiple images?
- Galaxy
clusters are the largest gravitational bound structures in the universe and can
contain thousands of galaxies. In addition to galaxies and gas, the clusters
are mostly made up of dark matter, an imperceptible by direct detection of
light of a still unknown nature.
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- To study
gravity lens' cosmological models often use quasars, the brightest astronomical
objects in the universe. Gravitational lensing occurs when a massive object is
between the observer and a bright celestial body. The massive object warps
space-time and modifies the path of light rays passing through it. In effect magnifying the image.
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- When
observing a distant quasar through a galaxy or cluster of galaxies, if the
lensing effect is strong enough, several images of the same celestial body are
formed.
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- The image
presents light curves for the four bright images of the “SDSS J1004+4112”
gravitational lensing system. The observations were carried out over 14.5 years
with the 1.2 meter telescope.
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- The four
images of the quasar observed actually correspond to a single quasar whose
light is curved on its path towards us by the gravitational field of the galaxy
cluster.
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- Since the
trajectory followed by the light rays to form each image is different, we
observe them at different instants of time; in this case we have to wait 6.73
years for the signal we observed in the first image to be reproduced in the
fourth one.
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- Measuring
these time delays helps to better understand the properties of galaxies and
clusters of galaxies, their mass and its distribution, in addition to providing
new data for the estimation of the Hubble constant.
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- This time
delay has made it possible to more accurately reconstruct the mass distribution
of the galaxy cluster that acts as a lens.
In particular, it has been possible to constrain the distribution of
dark matter in the inner region of the cluster, since the lensing effect is
sensitive not only to ordinary matter but also to dark matter.
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- The
calculation of the time delay is also being very useful to determine the distribution
of stars and other compact objects in the intracluster medium, as well as to
calculate the size of the quasar’s accretion disk, all of which contribute to
advancing our understanding of the formation of structures and their evolution
in the universe.
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- James Webb
sees the same supernova three times in an epic gravitational lens. The
mission continues to dazzle and amaze with every image it beams back to Earth,
and a recent observation depicting not one, not two, but three images of the
same galaxy,
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-
Gravitational lensing happens when light is bent or warped around a
massive celestial object that emits an enormous amount of gravity, most
commonly a star like our Sun, but can also happen with massive galaxies.
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- The
triple-imaged object is a supernova-hosting galaxy whose light is being
distorted and bent by the massive galaxy cluster known as RX J2129, which is
located approximately 3.2 billion light years from Earth.
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- Astronomers
have determined the three separate images are all different ages and
characteristics given the varying varying distances that light had to travel in
each one.
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- The oldest
image containing the astronomical transient supernova, “AT 2002riv”, has been determined to be
a Type Ia supernova and is identified by the two parallel lines on either side
of it.
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- This is
followed by an image as the distant galaxy appears 320 later, and the third
image is how it appeared 1,000 days post-AT 2002riv. Both images occurring 320
and 1,000 days after the first image show the supernova completely gone from
view.
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- The almost
uniform luminosity of a Type Ia supernova could also allow astronomers to
understand how strongly the galaxy cluster RX J2129 is magnifying background
objects, and therefore how massive the galaxy cluster is.
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-
Gravitational lensing is one of the most historic predictions of Albert
Einstein’s theory of general relativity, and was first discovered in 1979 when
two quasars were observed to be in close proximity to each other, but turned
out to be the same object whose light had been split in two, similar to what RX
J2129 did to the distant galaxy in the recent JWST observation.
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- While
gravitational lensing is used to observe large objects like supernovae, a
method known as gravitational microlensing is equally used to find exoplanets.
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- How many
more supernovae will JWST observe, and what else will we learn about
gravitational lensing in the coming years and decades? Only time will tell, and
this is why we do science!
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March 14, 2023 GRAVITY
LENS - create multiple images? 3917
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--- Wednesday, March 15, 2023 ---------------------------
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