It looks like a distant ring with three bright jewels, but the latest Webb Telescope (JWST) image is actually the view of a distant quasar lensed by a nearby elliptical galaxy. The telescope’s Mid-Infrared Instrument (MIRI) looked at the faint show during a study of dark matter and its distribution in the Universe.
We can see this ghostly vision thanks to the gravitational lensing of the quasar. Such a lens creates one of the largest natural telescopes in nature. It uses the gravitational effect of matter to warp space. All matter does this, but the largest conglomerates of it do more. So, for example, a galaxy cluster and its clustered stars, planets, gas clouds, black holes—and dark matter—warp space a bit. So does an individual galaxy.
When this happens, the path of light from more distant objects around (or through) the lens is also distorted. The lens magnifies the view of those distant objects between us and the lensing mass. So thanks to gravitational lensing, astronomers often get intriguing views of objects otherwise too faint or distant for detailed study.
A lensed view of a distant quasar
The distant quasar RX J1131-1231 that JWST imaged for this view is located about six billion light-years from Earth. Astronomers know that there is a supermassive black hole at the heart of the galaxy. It emits high-energy X-rays, which the Chandra X-ray Observatory and the XMM-Newton orbiting telescope detected. The Hubble Space Telescope has also spotted this scary-looking object.
Those X-rays tell astronomers that something very energetic is happening in the galaxy – which is why it’s often called a quasar. X-ray emissions are produced by a superheated accretion disk and eventually bounce off the inner edge of the disk. Astronomers can get a spectrum of that reflected X-ray emission—but they must take into account the fact that it is affected by the black hole’s strong gravitational pull. The greater the difference in the spectrum, the closer the inner edge of the disk is to the black hole. In this case, the emissions come from a region that extends only three times the radius of the event horizon. This suggests that the black hole is spinning very, very fast – at half the speed of light.
JWST’s infrared observation of the center of the lensed quasar allows astronomers to probe the region around its heart. They should be able to reveal the details of the distribution of matter in the region, which should help them understand the distribution of dark matter there.
Black Hole History Map
The central supermassive black hole at the heart of the quasar RX J1131-1231 has its own tale to tell. Those X-ray emissions from its accretion disk provide clues about how fast that black hole grew over time and how it formed. There are several main theories about the growth of black holes. We know that those with stellar mass come from the death of supermassive stars. They explode as supernovae. What is left collapses and this creates the black hole.
However, supermassive ones in the hearts of galaxies probably form in one of two ways. They can come from the accumulation of material over a long period of time during collisions and mergers between galaxies. If this happens, a growing black hole collects material into a stable disk. If there is a steady diet of new material from the disc, this should lead to a rapidly spinning black hole. On the other hand, if the black hole grew due to many small accretion episodes, its diet would come from random directions and its rotation rate would be slower.
So what’s the story of the bright, supermassive monster at the heart of RX J1131-1231? All observations so far point to a rapidly rotating black hole. This means it is likely to grow through mergers and acquisitions. Further observations of its high-energy activity should help astronomers as they probe deeper into the Universe and look for objects in the earliest and earliest epochs of cosmic time. JWST’s contribution helps them use gravitational lensing to spot these things. At the same time, they can map the distribution of dark matter that helps the Universe create those natural magnifying glasses.
For more information
Webb Admires Bejeweled Ring
The distant quasar RX J1131
RX J1131-1231: Chandra & XMM-Newton provide direct measurement of distant black hole spin