Wednesday, March 15, 2023

3917 - GRAVITY LENS - create multiple images?

 

-   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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