Wind from black holes could influence the development of surrounding galaxies

Clouds of gas in a distant galaxy are pushed faster and faster (at more than 10,000 miles per second) among nearby stars by bursts of radiation from the supermassive black hole at the galaxy’s center. It’s a discovery that helps illuminate how active black holes can continually shape their galaxies by stimulating or quenching the development of new stars.

A team of researchers led by Catherine Grier, a professor of astronomy at the University of Wisconsin-Madison, and recent graduate Robert Wheatley, revealed the existence of this accelerating gas using years of data collected from of a quasar, a type of particularly bright and turbulent black hole, located billions of light years away. Bootes constellation. 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 centers of most galaxies. Quasars are supermassive black holes surrounded by disks of matter attracted by the enormous gravitational power of the black hole.

“The material from that disk is still falling into the black hole, and the friction of that pulling and pulling heats the disk and makes it very, very hot and very, very bright,” Grier explains. “These quasars are really bright, and because there is a wide temperature range from the interior to the most distant parts of the disk, their emission covers almost the entire electromagnetic spectrum.”

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

The researchers used more than eight years of observations of a quasar called SBS 1408+544, collected by a program led by the Sloan Digital Sky Survey, now known as the Black Hole Mapper Reverberation Mapping Project. They tracked the winds composed of gaseous carbon, spotting the missing light from the quasar, the light absorbed by the gas. But instead of being absorbed in exactly the right place on the spectrum that would indicate carbon, the shadow was moving further and further from home with each new look at SBS 1408+544.

“This change tells us that the gas is moving fast, and faster and faster,” Wheatley says. “The wind accelerates because it is pushed by the radiation projected by the accretion disk.”

Scientists, including Grier, suggested that they had previously observed accelerated winds from black hole accretion disks, but this had not yet been supported by data from a few observations. The new results come from approximately 130 observations of SBS 1408+544 made over nearly a decade, allowing the team to robustly identify the increase in velocity with high confidence.

The winds pushing gas out of the quasar are of interest to astronomers because they provide a means by which supermassive black holes could influence the evolution of the galaxies around them.

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

Depending on the circumstances, a quasar’s winds could provide pressure that constricts gases and accelerates the birth of a star in its host galaxy. Or it could eliminate that fuel and prevent a potential star from forming.

“Supermassive black holes are big, but they are really tiny compared to their galaxies,” says Grier. “That doesn’t mean they can’t ‘talk’ to each other, and it’s a way for one to talk to the other that we’ll need to take into account when we model the effects of these types of black holes. “

The study of SBS 1408+544, published today in The Astrophysics Journal included collaborators from York University, Pennsylvania State University, University of Arizona and others.