Three billion light-years away, a giant black hole blows with almost unimaginable violence. Its cosmic wind shatters a record in the ultraviolet.
The object is called J2318. It is a quasar, the extremely bright core of a distant galaxy. At its center, a supermassive black hole swallows matter. Its mass reaches 1.7 billion times that of the Sun, a high value but not exceptional for this type of object.
Around this gravitational monster, an accretion disk gathers gas and dust. The matter heats up intensely before falling toward the black hole. This furnace shines in several domains of the electromagnetic spectrum. It also emits enough light to push part of the gas into space despite the immense gravitational pull.
Artist's impression of a quasar powered by a supermassive black hole surrounded by a disk of hot matter.
Credit: ESO In the case of J2318, this expelled gas reaches 30% of the speed of light. That corresponds to about 200 million miles per hour (323 million km/h). According to researchers, no black hole wind this fast had ever been measured in the ultraviolet before.
On Earth, wind arises from pressure differences in the atmosphere. Near a quasar, nothing of the sort. The blast is driven by photons—the light particles emitted in colossal numbers by the incandescent disk.
These photons strike the gas atoms and ions, then transfer a tiny momentum to them. Added up by billions upon billions, these minuscule impacts can produce extreme acceleration. Yet a mystery remains: such intense light should strip electrons from atoms.
However, astronomers still observe signatures of carbon and silicon in the wind of J2318. To detect these clues, the team studied spectra obtained by the Sloan Digital Sky Survey. Just as a prism splits sunlight, these data reveal the wavelengths absorbed or emitted by quasars. These light fingerprints betrayed the presence of an ultra-fast outflow. They also allow us to estimate its speed.
The stakes go beyond a simple record. These winds carry enormous amounts of energy into their host galaxy. They can sweep away cold gas, the raw material for new stars. Central black holes might therefore slow down star formation and alter the entire evolution of galaxies.
Computer simulations already include this violent clash between black hole and galaxy. But observations remain essential to verify these models. Researchers will therefore continue the hunt for ultra-fast winds, from nearby galaxies to the most distant observable regions.