A stunning new image from the James Webb Space Telescope shows a supernova hosting a galaxy not once, not twice, but three times at different points in time.
This seemingly time-defying image by the James Webb Space Telescope (JWST) was made possible by the massive gravitational influence of the foreground galaxy cluster and a light-bending phenomenon predicted over a century ago by Albert Einstein called “gravitational lensing.”
In his theory of general relativity, Einstein predicted that mass warps the fabric of space and time, or “space-time.” This is similar to placing a ball on a stretched rubber sheet, with the ball causing a dent in the paper. The greater the mass of the ball, the greater the degree of torsion it causes. This is also true in the case of space-time, stars cause more “curvature” than planets, and galaxies cause more space-time “curvature” than stars.
This warp affects the passage of light as it passes past the mass body of a background object. In extreme cases, because light can take different paths around the lensed object than the back-lensed object on its way to us, it can cause the background object to be magnified or even visible at multiple points in the sky. This means that this phenomenon, “gravitational lensing” has become a powerful tool for astronomers in studying very distant objects.
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The lensing object in this new JWST image is galaxy cluster RX J2129, located about 3.2 billion light-years away in the constellation Aquarius. RX J2129 lenses the background of a red-colored supernova host galaxy that repeats it.
The supernova explosion was detected by astronomers using the Hubble Space Telescope and is a Type Ia supernova identified in 2022riv. They are often referred to as “standard candles” by astronomers due to how uniform their light is. This regularity means that Type Ia supernovae can be used as a tool for measuring cosmic distances because at the same distance they would look exactly the same.
As a gravitational lens, RX J2129 has created three images of this galaxy that are not the same in size, location, or even age due to the different paths that the light from the background galaxy takes and thus the different times it arrives at the JWST.
The light following the longest path shows the background galaxy at its oldest age and at a time when the supernova was still occurring. The following image shows the second longest galactic path after only 320 days, and the last with the shortest light path 1000 days after the first. In both subsequent images, the AT 2022riv supernova has already faded from view.
Also visible in the upper right corner of the image are several background objects that appear as concentric arcs of light due to the warping effect of gravitational lenses.
Observations were made by JWST using the Infrared camera (Opens in a new tab) (NIRSpec) which was able to measure the brightness of AT 2022riv, a very distant and therefore early supernova. The powerful Space Telescope was also supposed to perform spectroscopy of the light from the event, which would allow comparison of this distant supernova with Type Ia supernovae that have recently occurred in the local universe.
This comparison can be used to test the accuracy of these supernovae’s use when measuring distances, and thus validate the results of one of astronomy’s most useful tools.
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