- 3742 - GRAVITATIONAL LENS - examples from new discoveries? A gravitational lens is a group of galaxies with immense gravity distorting the light beams coming from a galaxy directly behind them in our line of sight. The bending of multiple light beams causes multiple paths for the light.
---- 3741 - GRAVITATIONAL LENS - examples from new discoveries?
- Astronomers have just measured a time delay of 6.73 years, the longest ever detected for a gravitational lens, between multiple images of the same quasar. This result was obtained after 14.5 years of observation at the FLWO observatory of the Harvard-Smithsonian Center for Astrophysics (USA). It will improve knowledge about galaxy clusters and the dark matter they contain.
-
- Galaxy clusters are the largest gravitationally 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“, imperceptible by direct detection of light, of a still unknown nature.
-
- Obtaining new data on how it is distributed helps to improve knowledge about the evolution and structure of the universe, one of the main goals of astrophysics and modern cosmology. Cosmological models often use quasars, the brightest astronomical objects in the universe, and ‘gravitational lenses’.
-
- 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.
-
- 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.
-
- This observation presents new 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 m telescope.
-
- The four images of the quasar that were observed actually correspond to a single quasar whose light is curved on its path towards us by the gravitational field of the galaxy cluster.
-
- 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.
-
- 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 for the Universe‘s expansion. . This measurement has made it possible to study the mass distribution of the cluster. It made it possible to more accurately reconstruct the mass distribution of the galaxy cluster that acts as a lens.
-
- 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.
-
- The calculation of the time delay is also being very useful for other studies, for example 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.
-
November 13, 2022 GRAVITATIONAL LENS - new discoveries? 3741
----------------------------------------------------------------------------------------
----- Comments appreciated and Pass it on to whomever is interested. ---
--- Some reviews are at: -------------- http://jdetrick.blogspot.com -----
-- email feedback, corrections, request for copies or Index of all reviews
--- to: ------ jamesdetrick@comcast.net ------ “Jim Detrick” -----------
--------------------- --- Wednesday, November 16, 2022 ---------------------------
No comments:
Post a Comment