New Supernova Revealed with Gravitational Lens in Cosmic Illusion

Astronomers have made a startling discovery. They've found a galaxy that magnified a background, Type Ia supernova by 30 times through gravitational lensing. The new findings are the first example of strong gravitational lensing of a supernova.

Gravitational lensing is essentially what happens when a nearer object acts as a lens to magnify an object that's much further away. This phenomenon can allow scientists to observe objects in space that they wouldn't normally be able to see. The type of supernova in this case, Type Ia (SNIa), is tremendously useful for understanding components of the universe, such as dark energy and dark matter.

SNIa have strikingly similar peak luminosities, regardless of where they happen in the universe. This property in particular allows astronomers to us SNIa as standard candles to measure cosmological distance independent of the universe's expansion. In fact, distance measurement with SNIa was key to discovering the accelerating expansion of the universe.

In this case, the researchers spied a supernova named PS1-10afk. Yet while it displayed the same color and light curve as a Type Ia supernova, it was far too bright. In fact, its peak brightness was 30 times greater than expected. Generally, supernovae that shine brighter than Type Ia have higher temperatures (bluer colors) and larger physical sizes.

"We found a second explanation," said Marcus Werner, one of the researchers, in a news release. "and it required only well demonstrated physics: gravitational lensing. If there was a massive galaxy in front of PS1-10afk, it could warp space-time to form magnified images of the supernova."

That's exactly what happened. The researchers looked at their data a bit further and found evidence of a foreground galaxy which was the right size to explain the gravitational lensing of the supernova.

"In the future, when a target is identified as a possible lensed Type Ia supernova, high-resolution follow-up observations can be taken to resolve the individual image components," said Robert Quimbly, one of the researchers, in a news release. "The discovery and selection method we have crafted may thus soon improve our understanding of our expanding universe."

The findings are published in the journal Science.