It looks like a distant ring with three sparkling jewels, but the latest image from the Joint Webb Space Telescope (JWST) is actually a view of a distant quasar being collided by a nearby elliptical galaxy. The telescope's Mid-Infrared Instrument (MIRI) observed the faint feature as part of a study of dark matter and its distribution in the universe.
We can observe this ghostly vision thanks to the quasar's gravitational lensing. This lensing forms one of nature's largest natural telescopes. It uses the gravitational effect of matter to bend space. All matter does this, but larger collections of it do it even more. For example, galaxy clusters and their totality of stars, planets, gas clouds, black holes – and dark matter – bend space quite strongly. The same is true for a single 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 these far-off objects between us and the lensing mass. So, thanks to gravitational lensing, astronomers often get fascinating views of objects that would otherwise be too dim or too far away for detailed study.
A lens view of a distant quasar
The distant quasar RX J1131-1231, which the JWST captured for this image, lies 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 were detected by the Chandra X-ray Observatory and the XMM-Newton orbiting telescope. The Hubble Space Telescope has also observed this eerie-looking object.
This image shows the quasar RX J1131-1231, taken by NASA's Chandra X-ray Observatory and the Hubble Space Telescope. The JWST image is in the infrared. Image credit: X-ray: NASA/CXC/Univ of Michigan/RCReis et al; Optics: NASA/STScI
These X-rays tell astronomers that something very energetic is happening in the galaxy – which is why it is often called a quasar. The X-ray emissions are generated by a superheated accretion disk and eventually bounce off the inner edge of the disk. Astronomers can record a spectrum of these reflected X-ray emissions – but they must take into account that it is affected by the black hole's strong gravitational pull. The larger the change in the spectrum, the closer the inner edge of the disk is to the black hole. In this case, the emissions are coming from a region 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.
The JWST's observation of the lensed quasar in the mid-infrared will allow astronomers to study the region around its center. They should be able to tease out details of the distribution of matter in the region, which should help them understand the distribution of dark matter there.
Mapping the history of the black hole
The central supermassive black hole at the heart of the quasar RX J1131-1231 has its own story to tell. The X-ray emissions from its accretion disk provide clues about how quickly this black hole grew over time and how it formed. There are a few main theories about how black holes grow. We know that stellar-mass ones are formed from the death of supermassive stars. They explode as supernovas. What's left collapses, creating the black hole.
However, the supermassive black holes at the center of galaxies probably form in one of two ways. They could be formed by the accumulation of material over a long period of time as galaxies collide and merge. When that happens, a growing black hole collects material in a stable disk. If it constantly receives new material from the disk, that should result in a rapidly rotating black hole. On the other hand, if the black hole grows due to many small accretion episodes, its food would come from random directions and its rotation speed would be slower.
So what's the story of the bright, supermassive monster at the heart of RX J1131-1231? All observations so far show a rapidly rotating black hole. That means it probably grew through mergers and collisions. Further observations of its high-energy activity should help astronomers probe deeper into the Universe and discover objects at ever earlier epochs of cosmic time. The JWST contribution helps them use gravitational lensing to discover these things. At the same time, they can map the distribution of dark matter, which helps the Universe create these natural magnifying glasses.
For more informations
Webb admires jeweled ring
Distant Quasar RX J1131
RX J1131-1231: Chandra and XMM-Newton enable direct measurement of the rotation of distant black holes
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