PS1-10afx: `Standard Candle' Supernova
Magnified by Strong Gravitational Lensing

PS1-10afx was discovered by the Panoramic Survey Telescope & Rapid Response System 1 (Pan-STARRS1). From its redshift, we can determine that it exploded over 9 billion years ago, which places it far further than typical Pan-STARRS1 discoveries. Based on this distance and its relatively bright appearance, the Pan-STARRS1 team concluded that PS1-10afx was intrinsically very luminous. However, as they point out, there are no physical models that can explain how a supernova could simultaneously be so luminous, so red, and evolve so fast.

Looking at the data, I realized that PS1-10afx was very similar to normal Type Ia supernovae, the "standard candles" used to discover the accelerating expansion of our universe, but it was 30 times brighter than expected. This suggests that PS1-10afx is actually a normal Type Ia supernova that is being magnified by an external source. Only a gravitational lens can provide the needed magnification while preserving spectral features, colors, and light curve shape.

Calculations by Masamune Oguri predict that Pan-STARRS1 should discover about 1 such gravitationally lensed Type Ia supernova. It is thus perfectly plausible that PS1-10afx is the first Type Ia supernova to be strongly magnified by a gravitational lens. In the future, such discoveries can be used to study the nature of dark matter, test theories of gravity, and help reveal what our universe is made of.

Read the full press release here

Robert Quimby
Distinguished Postdoctoral Fellow
Kavli Institute for the Physics and Mathematics of the Universe (Kavli IPMU)
University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, 277-8583, Japan