Stephan’s Quintet. Image credit: NASA, ESA, CSA and STScI
JWST was able to determine the composition of the gas around the supermassive black hole of NGC 7319, one of five galaxies in Stephan’s Quintet. This was one of the telescope’s first scientific targets, which observed gas in this active galaxy core at never-before-detected wavelengths.
With his near-infrared instrument, he was able to see atomic hydrogen and molecular hydrogen, which is formed when two hydrogen atoms come together. He also saw iron ions. This is an excellent marker of where the hot gas is located around the supermassive black hole. Even though black holes don’t emit light, when they feed like this, they are disorderly eaters. The intense gravity heats the material they are eating, creating intense radiation.
Near-IR comspition of gas around the supermassive black hole of NGC 7319. Image credit: NASA, ESA, CSA and STScI
The supermassive black hole at the center of NGC 7319 has a mass equivalent to 24 million times that of our Sun or about six times Sagittarius A*, which is at the center of the Milky Way. But unlike Sagittarius A*, this supermassive black hole has a stupendous emission of radiation – as if 40 billion suns were shining at once.
Hydrogen and iron aren’t the only things the JWST was able to observe. In its mid-infrared observations, the telescope saw an outflow of hot gas that contained hot, ionized gases, including iron, argon, neon, sulfur and oxygen. And the immediate area around the black hole is rich in hydrogen and silicate dust — like grains of sand, but much smaller.
Mid-infrared spectrum of the gas around the supermassive black hole and at an exit. Image credit: NASA, ESA, CSA and STScI
JWST also observed the movement and velocity of the gas. Just as an ambulance siren has a higher pitch as it approaches you, the wavelength of electromagnetic radiation from light-emitting objects changes as it approaches or moves away from you. So the telescope could tell how the gas was moving and how fast.
The gas velocity around the supermassive black hole. Image credit: NASA, ESA, CSA and STScI
Studying supermassive black holes in nearby galaxies allows us to understand them anywhere in the Universe. Stephan’s Quintet is made up of four galaxies in a compact group and one that appears to be close to them, but only visually. The group is located 290 million light-years from Earth.
The JWST group photo is 150 million pixels and was constructed from nearly 1,000 separate image files. The telescope can see individual stars and the bright core of NGC 7320, which is the closest (and farthest to the left) of the group.