Astronomers are like the detectives of the cosmos, searching for clues to mysteries in the universe with an ever-growing toolkit of telescopes, spectroscopes, robotic probes, and other instruments. But sometimes, the universe chips in with a gadget of its own: a galactic magnifying glass.
An international team of astronomers has discovered a distant supernova that was magnified in brightness and split into four separate images as its light passed through a galaxy on its way to Earth. The light from the exploding star, called iPTF16geu, took about 4.3 billion years to reach Earth and show up in telescopes—that’s nearly as old as the Earth itself. As it traveled, the light reached a galaxy located about 2 billion light-years away from Earth. The galaxy’s gravitational field bent the light rays around it as they passed, magnifying and swinging them into different paths, a phenomenon known as gravitational lensing. When they finally reached Earth, they appeared as four different orbs around the galaxy—four different images of the same cosmic explosion:
The astronomers say the galaxy also magnified the light from the supernova by a factor of 52.
“I've been looking for a lensed supernova for about 15 years. I looked in every possible survey, I've tried a variety of techniques to do this and essentially gave up, so this result came as a huge surprise,” said Ariel Goobar, a University of Stockholm professor and lead author of the study published Thursday in the journal Science.