In the latest images from the James Webb Space Telescope, a luminous halo resembling a precious gem reveals a colossal black hole. This resplendent ring, an "Einstein ring," intrigues with its four bright points.
A massive galaxy (blue point) bends the light emitted by an active black hole (orange points) through a phenomenon known as gravitational lensing.
Credit: NASA/ESA/CSA
This halo originates from a quasar, a supermassive black hole at the heart of a young galaxy named RX J1131-1231, located about 6 billion light-years away in the Crater constellation. The quasar projects enormous amounts of energy by absorbing matter.
The observed luminous circle results from a gravitational lensing phenomenon. The light from the quasar travels through space-time curved by the gravity of an intermediate galaxy, appearing thus deflected. This galaxy, visible as a blue point at the center of the luminous ring, amplifies our view of RX J1131-1231, which would otherwise be almost invisible.
Gravitational lenses sometimes produce multiple points. In this case, the four bright points around the ring are mirror images of a single point, duplicated by the lensing effect. Perfect Einstein rings are rare, and this observation does not show a perfect circle.
Gravitational lenses like these offer a window into distant objects and their structures. In 2014, researchers determined the rotational speed of the supermassive black hole of RX J1131-1231 through this phenomenon. Moreover, these observations allow the measurement of the mass of intermediate galaxies and the estimation of the amount of dark matter they contain.
This composite image of RX J1131-1231, using photos from the Hubble Space Telescope and the Spitzer Telescope, highlights the quasar's multiplication by the gravitational lens.
Credit: NASA/CXC/Univ of Michigan/R.C.Reis et al
These luminous distortions thus constitute a valuable tool for uncovering the secrets of dark matter and improving our understanding of the Universe.