A team of astronomers have solved a mystery surrounding the brightness of the supernova PS1-10afx.
The supernova was first discovered in 2010 using the Panoramic Survey Telescope and Rapid Response System, according to Sci-News. Its peak brightness was 30 times greater than scientists expected.
Several qualities that make PS1-10afx different from most supernovae include evolving too quickly, having a larger host galaxy and being more red than others. Astronomers concluded from these anomalies that PS1-10afx was a totally new kind of supernova.
"Generally, the rare supernovae that have been found to shine brighter than Type Ia usually have high temperatures (blue colors) and larger physical sizes (and thus lower light curves). New physics would thus be required to explain PS1-10afx as an intrinsically luminous supernova," said Dr. Robert Quimby, lead author of the study from the University of Tokyo's Kavli Institute for the Physics and Mathematics of the Universe.
The team believed the supernova was a normal Type Ia supernova that was magnified by a lens in the form of a large object that was nearby, such as a black hole, BBC News reported. Quimby said that the team did not have any direct evidence of a lens, but reasoned that the lens would still be there today.
The scientists used the Keck telescope in Hawaii in 2013 to observe the host galaxy of PS1-10afx and ultimately find the lens.
"Looking at the spectra we could check to see if there was light coming from two sources at two separate distances, which is what we found," Quimby said. "There is a second, previously unidentified galaxy, hiding in plain sight in front of the supernova."
The team announced that the second galaxy was located between Earth and the supernova, and that it had magnified the explosion through gravitational lensing, The National Post reported.
The study was published in the journal Science.
The discovery can help astronomers measure the expansion of the universe, BBC News reported.
"Our discovery implies there are many more gravitational lensed supernovae that are barely resolved, like PS1 10afx," said Prof. Masamune Oguri of the University of Tokyo. "Our selection method can soon be applied to future surveys to improve our understanding of the expanding Universe."
