At the center of any massive galaxy, you’ll most likely find one daunting portion of space-time: a supermassive black hole. These gigantic gravity wells are so enormous, they have a mass that’s equal to millions or even billions of times the mass of our Sun. While extremely powerful, black holes can be relatively hard to study. But now researchers have accurately measured a substantial byproduct of supermassive black holes: winds that travel at more than 62,000 miles per second.
Researchers have long theorized that when a black hole draws in matter with its large gravitational pull, the process produces huge x-ray-emitting wind gusts, which emanate from the hole and shoot out into the nearby galaxy. While this concept had been widely accepted in the scientific community, no one really knew what shape these winds took. Using NASA’s Nuclear Spectroscopic Telescope Array and the ESA’s XMM-Newton telescope, researchers from Caltech and Keele University of England were able to measure the speed, shape, and size of the winds blasting out from PDS 456—a super bright black hole located two billion light-years away.
PDS 456 is a type of black hole known as a quasar, meaning it is extremely luminous. According to Emanuele Nardini, the lead author of the study, which published in Science, the winds are actually a result of the brightness surrounding the black hole. “When the energy of the matter that is folding into the black hole is released, this energy is turned into heat, creating huge luminosity,” Nardini tells Popular Science. “When this luminosity is high enough to counteract the black hole’s gravitational attraction (about 10 billion times that of the Sun), it can push wind gusts outward.”
These winds carry more energy every second than the energy that would be emitted by a trillion Suns.
To get a good look at these winds, NuSTAR and XMM-Newton observed PDS 456 on five separate instances in 2013 and 2014. XMM-Newton viewed the low-energy part of the x-ray spectrum while NuSTAR looked at the high-energy end of the spectrum. Specifically, the telescopes looked for traces of iron, which previous studies had confirmed were located in these winds.
“These gusts are completely ionized,” says Nardini. “Every element is completely stripped of its electrons; the only element that is left is iron. If iron is in front of the black hole, it blocks the radiation from the black hole, so we see a dip in the intensity of the light coming from the black hole.”
By observing the patterns of iron in front of the black hole and at its sides, the researchers were able to determine that these winds push out in every direction from the black hole. And these winds are pretty speedy, traveling at one-third the speed of light. They also carry more energy every second than the energy that would be emitted by a trillion Suns.
Nardini notes that the winds greatly affect the supermassive black hole’s surrounding galaxy, notably by regulating the formation of new stars. “If the wind is powerful enough, it triggers an avalanche and carries away all the gas along its path that’s in the galaxy, which is usually used to form stars.” The researchers also believe the winds serve as an ancient form of “communication” between black holes and galaxies, binding the two together.
“Most of the galaxies today are very inactive—neither the black hole is active nor is there star formation—it’s very steady,” says Nardini. “There must be some kind of mechanism in the past of their lifetime that has shaped them like we see them today. These winds are a possibility.”
