Astronomers using the Hubble Space Telescope, including Museum research associate Or Graur, have found the cosmic equivalent of a four-leaf clover: four images of the same supernova arranged in a pattern called Einstein’s Cross. This unique observation is described in the March 6 issue of Science.
Ordinarily, a single image of the supernova’s light can be seen from Earth. But as the light passes through the galaxy cluster, gravity bends it onto new paths, several of which are pointed at Earth, creating a multiple image in an effect known as gravitational lensing. Although astronomers have discovered dozens of similar images of galaxies and quasars, this is the first time a supernova has resolved into several images.
Led by the University of California, Berkeley, this research will help astronomers refine their estimates of the amount and distribution of dark matter in the lensing galaxy and cluster. Dark matter cannot be seen directly, but is thought to make up most of the universe’s mass.
“The multiple images of the supernova give lens modelers a unique way to test their models of how the dark matter is distributed in this galaxy cluster,” said Dr. Graur, a research associate in the Museum’s Department of Astrophysics and an assistant research scientist at New York University who was an author on the paper.
The authors have nicknamed the supernova Refsdal in honor of Norwegian astronomer Sjur Refsdal, who, in 1964, first proposed using time-delayed images from a lensed supernova to study the expansion of the universe.