Hubble Captures Supernova Split Four Ways by a Gravitational Lens for the First Time
Astronomers recently discovered that Hubble was able to capture four separate images of the same distant supernova. The so-called "Einstein's cross" was made possible by gravitational lensing, a tenet of Einstein's theory of relativity, and the study marks the first time we've observed the phenomenon in relation to a supernova.
Lead author of the study Patrick Kelly, a UC Berkeley postdoctoral scholar, was performing research based on infrared images taken by the Hubble Space Telescope when he discovered the supernova- and that the telescope had captured it four separate times.
"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," said Kelly.
Kelly and his team were able to observe this very distant astrophysical event as a result of gravitational lensing. Gravitational lensing refers to the effect in which a distribution of matter between a distant light source and its observer bends the light traveling through spacetime away from its source. In this case, massive galaxy inside a cluster of galaxies created a magnifying effect with their combined gravitational pulls, allowing Hubble to observe a gravitationally lensed supernova for the first time.
"These gravitational lenses are like a natural magnifying glass. It's like having a much bigger telescope," Kelly said. "We can get magnifications of up to 100 times by looking through these galaxy clusters."
The set of four images is called an "Einstein's cross" because gravitational lensing was first predicted by Einstein as part of his theory of relativity. The first gravitational lens was finally observed in 1979, when a team of researchers in Arizona discovered a quasar that had been captured in two separate images, now affectionately known as the "Twin Quasar." As a result, the phenomenon of gravitational lensing has been well-documented, but this is the first time that we've been able to see a lensed supernova.
Alex Filippenko, UC Berkeley professor of astronomy and a member of Kelly's team, said, "We've been searching for a strongly lensed supernova for 50 years, and now we've found one."