iPTF16geu: A multiply imaged, gravitationally lensed type Ia supernova

TL;DR

This paper reports the discovery and analysis of a gravitationally lensed Type Ia supernova, with four images magnified over fifty times, providing insights into lensing galaxy sub-structures and the supernova's properties.

Contribution

First observation of a multiply-imaged, gravitationally lensed Type Ia supernova with high-resolution imaging revealing four images and sub-structure evidence in the lensing galaxy.

Findings

Four images of the supernova were resolved with high spatial resolution.

The supernova was magnified over fifty times by gravitational lensing.

Evidence for sub-structures in the lensing galaxy was found.

Abstract

We report the discovery of a multiply-imaged gravitationally lensed Type Ia supernova, iPTF16geu (SN 2016geu), at redshift $z=0.409$. This phenomenon could be identified because the light from the stellar explosion was magnified more than fifty times by the curvature of space around matter in an intervening galaxy. We used high spatial resolution observations to resolve four images of the lensed supernova, approximately 0.3" from the center of the foreground galaxy. The observations probe a physical scale of $\sim$1 kiloparsec, smaller than what is typical in other studies of extragalactic gravitational lensing. The large magnification and symmetric image configuration implies close alignment between the line-of-sight to the supernova and the lens. The relative magnifications of the four images provide evidence for sub-structures in the lensing galaxy.