James Webb Space Telescope discovers shock wave near a supermassive black hole (image)
Using the James Webb Space Telescope (JWST), astronomers were able to image the structure of dust and gas around a distant supermassive black hole and discover a literal “shock” structure.
The team discovered that the energy heating up this swirling cloud of gas and dust actually comes from collisions with jets of gas moving at nearly the speed of light, called “shocks.” Previously, scientists had theorized that the energy heating up this dust comes from the supermassive black hole itself, which is what makes this unexpected twist.
The galactic home of this particular supermassive black hole is ESO 428-G14, an active galaxy located about 70 million light-years from Earth. The term “active galaxy” means that ESO 428-G14 has a central region, or “active galactic nucleus” (AGN), that emits strong and intense light across the entire electromagnetic spectrum due to the presence of a supermassive black hole that greedily devours the matter around it.
The shock AGN finding was made by members of the GATOS (Galactic Activity, Torus, and Outflow Survey) collaboration, who use special JWST observations to study the hearts of nearby galaxies.
“There is much debate about how AGN release energy into their surroundings,” said GATOS team member David Rosario, a lecturer at Newcastle University, in a statement. “We did not expect radio jets to cause such damage. And yet they do!”
Related: Dark matter could act as a “coupler” for supermassive black holes
Unlocking the secrets of a “noisy” black hole
All large galaxies are thought to have supermassive black holes at their centres, with masses between millions and billions of times that of the Sun. However, not all of these black holes are located in active galactic nuclei.
Take the Milky Way, for example. Our galaxy’s supermassive black hole Sagittarius A* (Sgr A*) is surrounded by so little matter that its “diet” of matter is equivalent to that of a human being who eats one grain of rice per million years. This makes Sgr A*, whose mass is about 4.3 million suns, a “quiet” black hole, but it certainly has some noisy neighbors.
Let us take the supermassive black hole at the heart of the galaxy Messier 87 (M87), which is about 55 million light years away from us. This black hole M87* is not only much more massive than Sgr A*, with a mass of about 6.5 billion suns, but it is also surrounded by huge amounts of gas and dust, which it feeds on.
This material cannot fall directly onto M87* because it carries angular momentum. This means that it forms a swirling, flattened cloud of gas and dust around the supermassive black hole, called an “accretion disk,” from which it is gradually fed.
Supermassive black holes don’t just sit passively in accretion disks waiting to be fed like a cosmic baby in a highchair. The enormous gravitational influence of these cosmic titans creates enormous tidal forces in the accretion disk, generating fiction that heats it to temperatures as high as 18 million degrees Fahrenheit (10 million degrees Celsius).
This causes the accretion disk to glow brightly, powering some of the AGN’s illumination. The enormous gravitational influence of these cosmic titans creates enormous tidal forces in the accretion disk, creating fiction that heats it to temperatures as high as 18 million degrees Fahrenheit (10 million degrees Celsius).
But that’s not all.
Like a naughty toddler, not all of a supermassive black hole’s “food” ends up in its “mouth.” Strong magnetic fields direct some of the matter in accretion disks toward the black hole’s poles, accelerating these charged particles to nearly the speed of light. It’s like your child throwing his food at you.
This material shoots outwards from the two poles of the black hole in the form of parallel astrophysical jets. These jets are also accompanied by the emission of light across the entire electromagnetic spectrum, especially radio waves.
Because of these contributions, AGNs can be so bright that they outshine the combined light of all the stars in the surrounding galaxy.
The dust that surrounds active galactic nuclei can often block our view of their centers by absorbing visible light and other wavelengths of electromagnetic radiation. However, infrared light can escape this dust, and conveniently, the JWST sees the cosmos in infrared. This means that the powerful space telescope is the perfect tool for peering into the center of active galactic nuclei.
When the GATO team did this for ESO 428-G14, they found that dust near the supermassive black hole spreads along its jet. This revealed an unexpected relationship between the jets and the dust, and suggested that these powerful outflows could be responsible for both heating and shaping the dust.
A closer look at the connection between jets and dust around supermassive black holes could shed light on the influence these cosmic titans have on shaping their galaxies and how material is recycled in AGNs.
“Having the opportunity to work with exclusive JWST data and access these stunning images before anyone else is beyond exciting,” said Houda Haidar, PhD student in the Department of Mathematics, Statistics and Physics at Newcastle University. “I feel incredibly lucky to be part of the GATOS team. Working closely with leading experts in the field is truly a privilege.”
The team’s research was published in the journal Monthly Notices of the Royal Astronomical Society.
