NASA has revealed the sharpest ever look at the edge of a black hole, and it could solve a decades–old galactic mystery.
Located 13 million light–years from Earth, the Circinus Galaxy is home to a supermassive black hole that is constantly blasting radiation into space.
The clouds of hot gas surrounding this black hole are so bright that seeing any real details has previously been all but impossible.
Now, NASA has used the James Webb Space Telescope (JWST) to unveil the strange and powerful forces on the very edge of this black hole.
Supermassive black holes like the one in Circinus remain active by constantly consuming matter from the surrounding galaxy.
Scientists had observed that this process creates a huge amount of infrared energy, but most telescopes weren’t sensitive enough to see where it was coming from.
Previously, scientists thought most of this radiation was coming from the black hole’s ‘outflow’ – a stream of superheated matter fired out from the core.
Now, these new observations from the JWST have turned that expectation on its head.
NASA has revealed the closest ever look at the edge of a black hole 13 million light–years from Earth, and it could help solve a decades–old galactic mystery. Pictured: The new James Webb Space Telescope image overlaid on the Hubble image
A black hole is the ultra–dense heart of a dead star where gravity is so strong that not even light can escape.
Supermassive black holes, like the one in the Circinus Galaxy, become ‘active’ by consuming vast quantities of matter from their surrounding galaxy.
As this matter falls inwards, it forms a dense doughnut–shaped ring called a torus that orbits the black hole.
A supermassive black hole gathers material from the torus’ inner walls to form an accretion disc, a swirling whirlpool of matter that circles the black hole like water going down a drain.
This accretion disk starts to get hotter through friction until it begins to glow bright enough to show up on our telescopes.
At the same time, that intense energy blasts a large portion of the infalling matter out of the black hole’s poles in the form of an outflow or black hole jet.
Although astronomers’ models make predictions about how these different parts should interact, it is extremely difficult to see this process in action.
The light from the accretion disk blocks out any details, while the incredibly dense torus hides the inner region of infalling matter from view.
The Circinus galaxy is home to an active supermassive black hole that constantly blasts infrared radiation into space. However, scientists have struggled to determine exactly where around the black hole this radiation comes from
Scientists would try to fit the different wavelengths of light they observed to the emissions from different regions of the black hole, but not everything could be made to fit neatly.
Most notably, some telescopes could detect an excess of infrared light coming from somewhere in the black hole, but didn’t have the resolution to work out where it was coming from.
Lead author Dr Enrique Lopez–Rodriguez, of the University of South Carolina, says: ‘Since the 90s, it has not been possible to explain excess infrared emissions that come from hot dust at the cores of active galaxies, meaning the models only take into account either the torus or the outflows, but cannot explain that excess.’
Models assumed that most of the mass, and therefore most of the emissions, would be in the outflow.
But to test this, astronomers needed a way to both filter out the interfering starlight and distinguish the infrared emissions of the torus from those of the outflows.
Luckily, the JWST offered an innovative solution to both of these problems.
The scientists used a tool called the Aperture Masking Interferometer, which essentially converts JWST into several smaller telescopes that all work together.
On Earth, interferometers are usually many different radio or optical telescopes that work together as if they were a single, enormous observatory.
Using a new technique, scientists were able to determine that most of the radiation is coming from a swirling doughnut of matter known as the taurus, not from the jet of ejected matter as previous studies had believed
The JWST can replicate this same trick by using a special cover with seven hexagonal holes.
Dr Lopez–Rodriguez told the Daily Mail: ‘Interferometry is the technique that provides us with the highest angular resolution possible.
‘Using aperture masking interferometry with the JWST is like observing with a 13–meter space telescope instead of a 6.5–meter one.’
Gathering data with this technique, the scientists were able to create an image of the central region.
This is the first extragalactic observation from an infrared interferometer in space, and offers an unprecedented look into the core of an active galaxy.
Contrary to previous estimates, around 87 per cent of the infrared emissions from hot dust in Circinus come from the areas closest to the black hole, while the outflow contributes less than one per cent.
This is a total reversal of what had been predicted by astronomers’ best models for supermassive black holes.
However, while the mystery of Circinus’ black hole has been solved, there are billions more supermassive black holes out there in the universe.
These images were possible thanks to a technique that converts the James Webb Space Telescope’s mirror (artist’s impression) into several smaller lenses that all work together to provide extreme resolution in a very small area
Circinus’ accretion disc was only moderately bright, so it makes sense that the torus would dominate its emissions.
But for brighter black holes, the opposite might still be the case, and far more case studies will be needed.
With this research, astronomers found a technique to investigate any black holes they chose, so long as they are bright enough for the Aperture Masking Interferometer to be useful.
Dr Lopez–Rodriguez says: ‘We need a statistical sample of black holes, perhaps a dozen or two dozen, to understand how mass in their accretion disks and their outflows relate to their power.’
