Thanks to a rare cosmic phenomenon, astronomers were able to witness an ancient, distant star explode as a supernova not once or twice, but on four separate occasions, according to a research published online Friday in the journal Science.
According to Space Daily, the supernova occurred directly behind a cluster of large galaxies that had enough combined mass to warp space-time. This forms a cosmic magnifying glass similar to the phenomenon of gravitational lensing, but which creates multiple images of the star.
This effect is known as an Einstein Cross, and the Washington Post explained that it was first predicted by Albert Einstein’s General Theory of Relativity roughly a century ago. Because the cluster was located between the supernova (which was nine billion light years away) and the instrument imaging it, the same explosion showed up around the galaxy four times.
A Michael Bay star
Astronomers have seen Einstein Crosses made by galaxies and black holes before, but marks the first time that they’ve witnessed the phenomenon with an exploding star, the newspaper noted. In this case, since the supernova occurred so far away, it would have been too faint to be seen from Earth unless it was being magnified by multiple galaxies.
As it turns out, the explosions were actually subjected to gravitational lensing twice. The massive cluster of galaxies originally bent the light of the supernova, likely producing three images, and one of those was bent a second time to produce the fourth one. In all, the light from the explosion was magnified 20 times, and astronomers are calling it a dream discovery.
“It’s perfectly set up, you couldn’t have designed a better experiment,” Dr. Brad Tucker of The Australian National University’s (ANU) Research School of Astronomy and Astrophysics and one of the study’s authors, told Space Daily. “You can test some of the biggest questions about Einstein’s theory of relativity all at once – it kills three birds with one stone.”
While astronomers have conducted searches for this type of phenomenon many times over the last two decades, this Einstein Cross was actually discovered during a search for distant galaxies by Dr. Patrick Kelly of the University of California, Berkeley. Not only did the find allow Kelly and his colleagues to test the Theory of Relativity, it also provided new insight into the amount of dark matter and dark energy in the universe, as well as the strength of gravity.
“It really threw me for a loop when I spotted the four images surrounding the galaxy,” Kelly said in a statement. “Basically, we get to see the supernova four times and measure the time delays between its arrival in the different images, hopefully learning something about the supernova and the kind of star it exploded from, as well as about the gravitational lenses.”
“It’s a wonderful discovery,” added Alex Filippenko, a professor of astronomy at UC Berkeley and a member of the research team. “We’ve been searching for a strongly lensed supernova for 50 years, and now we’ve found one. Besides being really cool, it should provide a lot of astrophysically important information.”