The Prescription of a Cosmic, Gravitational Lens: Exploding Stars Shed Light on Lenses

The NASA Hubble Space Telescope has captured the images of three distant exploding stars with help of a gravitational lens. The latest pictures of the supernovae offer researchers a powerful tool to check the prescription of these gravitational lenses.

Clusters of galaxies act as gravitational lenses since their powerful gravity bends light passing through them. This causes faraway objects behind the clusters to appear bigger and brighter than they actually area. In fact, the lenses can reveal objects that are otherwise too faint to see, even with the largest telescopes.

Now, scientists are learning exactly how much these objects were magnified-at least when it comes to these specific lenses. How much a gravitationally lensed object is magnified depends on the amount of matter in a cluster, including dark matter. In order to determine the prescription of the gravitational lenses, the researchers analyzed three supernovae, nicknamed Tiberius, Didius and Carcalla, which were lensed by the galaxy clusters Abell 383, RXJ1532.9+3021 and MACS J1720.2+3536, respectively.

"Here we have found Type Ia supernovae that can be used like an eye chart for each lensing cluster," said Saurabh Jha, one of the researchers, in a news release. "Because we can estimate the intrinsic brightness of the Type Ia supernovae, we can independently measure the magnification of the lens, which is not possible with other background sources."

The researchers used Hubble observations alongside observations from both space and ground-based telescopes to provide independent estimates of the distances to these supernovae. They then compared their results with independent theoretical models of the clusters' dark matter content. In the end, they found that the predictions fit the models.

"Building on our understanding on these lensing models also has implications for a wide range of key cosmological studies," said Saul Perlmutter, one of the researchers, in a news release. "These lens prescriptions yield measurements of the cluster masses, allowing us to probe the cosmic competition between gravity and dark energy as matter in the Universe gets pulled into galaxy clusters."

The findings are published in The Astrophysical Journal and the Monthly Notices of the Royal Astronomical Society.