Wind from black holes can influence the development of surrounding galaxies

Clouds of gas in a distant galaxy are being ejected faster and faster (at a speed of more than 16,000 kilometers per second) between neighboring stars by radiation explosions from the supermassive black hole at the center of the galaxy. It’s a discovery that helps illuminate the way active black holes can continually shape their galaxies by encouraging or undermining the development of new stars.

A team of researchers led by University of Wisconsin-Madison astronomy professor Catherine Grier and recent graduate Robert Wheatley revealed the accelerating gas using years of data collected from a quasar, a particularly bright and turbulent type of black hole billions of light-years away in the room. constellation Boötes. They presented their findings today at the 244th meeting of the American Astronomical Society in Madison.

Scientists believe that black holes are located at the center of most galaxies. Quasars are supermassive black holes surrounded by disks of matter that are pulled inward by the black hole’s enormous gravity.

“The material in that disk is always falling into the black hole, and the friction of that tug and pull heats the disk and makes it very, very hot and very, very bright,” says Grier. “These quasars are truly luminous, and because there is a wide temperature range from the inner to the distant parts of the disk, their emission covers almost the entire electromagnetic spectrum.”

The bright light makes quasars almost as old as the universe (a whopping 13 billion light-years away) visible, and the wide range of their radiation makes them particularly useful for astronomers to investigate the early universe.

Researchers used more than eight years of observations of a quasar called SBS 1408+544, collected by a program run by the Sloan Digital Sky Survey, now known as the Black Hole Mapper Reverberation Mapping Project. They tracked winds made up of gaseous carbon by seeing light from the quasar that was missing: light that was absorbed by the gas. But instead of being absorbed at exactly the right spot on the spectrum that would indicate carbon, the shadow shifted further from home with each new look at SBS 1408+544.

“That shift tells us that the gas is moving fast, and faster and faster,” Wheatley says. “The wind is speeding up because it is being pushed by radiation blown off the accretion disk.”

Scientists including Grier have suggested that they have observed accelerating winds from black hole accretion disks before, but this has not yet been supported by data from more than a few observations. The new results came from about 130 observations of SBS 1408+544 over nearly a decade, allowing the team to identify the increase in speed with high confidence.

The winds that push gas from the quasar are of interest to astronomers because they are one way that the supermassive black holes can influence the evolution of the galaxies that surround them.

“If they are energetic enough, the winds can travel all the way to the host galaxy, where they can have a significant impact,” Wheatley says.

Depending on conditions, a quasar’s winds can exert pressure that compresses gas and accelerates the birth of a star in its host galaxy. Or it could scour away that fuel and stop a potential star from forming.

“Supermassive black holes are big, but they are very small compared to their galaxies,” says Grier. “That doesn’t mean they can’t ‘talk’ to each other, and this is a way in which one can talk to the other that we will have to take into account when we model the effects of these types of black holes.”

The SBS 1408+544 study, published today in The Astrophysical Journal including employees from York University, Pennsylvania State University, University of Arizona and others.