Astronomers Witness Light Delayed by Almost 7 Years as It's Warped by a Galaxy Cluster - ScienceAlert

The combo of galaxies and dark matter in the cluster is really entangling the quasar light as it passes through.

"The four images of the quasar that we observe actually correspond to a single quasar whose light is curved on its path towards us by the gravitational field of the galaxy cluster," said José Antonio Muñoz Lozano, professor of the Department of Astronomy and Astrophysics and director of the Astronomical Observatory of the University of Valencia.

The combined gravity of the galaxies, plus the intermingled dark matter in the cluster can entangle light from more distant objects as it passes through or near the cluster.

It all helps them to understand how it affects the path of light from a distant quasar.

In addition to the mass distribution, observational data also helps understand other characteristics of the lensing cluster, said Raquel Fores Toribio, a postdoctoral student at the University.

"In particular, it has been possible to constrain the distribution of dark matter in the inner region of the cluster, since the lensing effect is sensitive not only to ordinary matter but also to dark matter," she said.

A recently published paper describes the team's use of new light curves for the four bright images of the SDSS J1004+4112 gravitational lensing system.