Black Hole "Hearts" Warm Galaxies, Control Growth
Ker Thanfor National Geographic News
November 21, 2008
Ker Thanfor National Geographic News
November 21, 2008
A colossal black hole nestled in the center of a distant galaxy controls its own growth and the growth of surrounding stars by pumping out energy at regular intervals, a new study says.
"It looks like a beating heart," said study team member Mateusz Ruszkowski, an astronomer at the University of Michigan.
The black hole resides in the center of the elliptical galaxy M84, 55 million light-years from Earth.
New images from NASA's Chandra X-Ray Observatory reveal that with every beat, the black hole shoots twin jets of superheated gas, or plasma, into the galaxy.
The plasma jets warm the cool gas around them, creating bubbles of hot gas that swell until they are several thousand light-years across.
As the bubbles form they create a "Russian doll" effect, in which one bubble is nested inside a larger one, Ruszkowski said.
Because the bubbles grow at a constant rate, the team determined the age of each bubble, revealing that the black hole pumps out energy once every ten million years.
Scientists knew that black holes could eject energy in rare and violent outbursts, but the new finding is the first direct evidence that they are also capable of gentler and more consistent discharges.
"Just like our hearts periodically pump our circulatory systems to keep us alive, black holes give galaxies a vital warm component," study co-author Alexis Finoguenov of the Max-Planck Institute for Extraterrestrial Physics in Germany, said in a statement.
(Interactive: Put a human heart though its paces.)
Cosmic Birth Control
Black holes are objects that have gravity so strong that not even light can escape.
New images from NASA's Chandra X-Ray Observatory reveal that with every beat, the black hole shoots twin jets of superheated gas, or plasma, into the galaxy.
The plasma jets warm the cool gas around them, creating bubbles of hot gas that swell until they are several thousand light-years across.
As the bubbles form they create a "Russian doll" effect, in which one bubble is nested inside a larger one, Ruszkowski said.
Because the bubbles grow at a constant rate, the team determined the age of each bubble, revealing that the black hole pumps out energy once every ten million years.
Scientists knew that black holes could eject energy in rare and violent outbursts, but the new finding is the first direct evidence that they are also capable of gentler and more consistent discharges.
"Just like our hearts periodically pump our circulatory systems to keep us alive, black holes give galaxies a vital warm component," study co-author Alexis Finoguenov of the Max-Planck Institute for Extraterrestrial Physics in Germany, said in a statement.
(Interactive: Put a human heart though its paces.)
Cosmic Birth Control
Black holes are objects that have gravity so strong that not even light can escape.
Supermassive black holes have the same masses as up to a billion suns or more and have been detected at the center of many large galaxies, including our own Milky Way.
The plasma jets spotted in M84 are actually coming from the ring of gases and dust—called the accretion disk—that spirals into the galaxy's supermassive black hole, feeding its growth.
The plasma jets spotted in M84 are actually coming from the ring of gases and dust—called the accretion disk—that spirals into the galaxy's supermassive black hole, feeding its growth.
But as M84's bubbles expand, they prevent gases in the accretion disk from cooling and clumping together to form new stars or from sinking toward the center of the galaxy and into the black hole.
If galactic black holes did not disrupt their own intake from time to time like this, they would continually gain mass, and their borders—or event horizons—would creep ever outward.
"If you can eject energy from the central black hole, you can solve two problems at the same time: You can starve the black hole and also heat the gas so that stars will not be forming as efficiently," Ruszkowski told National Geographic News.
The research is detailed in a recent issue of the Astrophysical Journal.
Kevin Schawinski, an astrophysicist at Yale University who was not involved in the paper, said that "the really fascinating aspect of this [discovery] is that they see evidence of this happening repeatedly in the same galaxy, demonstrating that this is a periodic process."
It's still unclear, however, why the plasma jets are released at regular intervals.
One idea is that it takes time between each outburst for enough gas to cool and settle onto the black hole's accretion disk to trigger another outburst.
If galactic black holes did not disrupt their own intake from time to time like this, they would continually gain mass, and their borders—or event horizons—would creep ever outward.
"If you can eject energy from the central black hole, you can solve two problems at the same time: You can starve the black hole and also heat the gas so that stars will not be forming as efficiently," Ruszkowski told National Geographic News.
The research is detailed in a recent issue of the Astrophysical Journal.
Kevin Schawinski, an astrophysicist at Yale University who was not involved in the paper, said that "the really fascinating aspect of this [discovery] is that they see evidence of this happening repeatedly in the same galaxy, demonstrating that this is a periodic process."
It's still unclear, however, why the plasma jets are released at regular intervals.
One idea is that it takes time between each outburst for enough gas to cool and settle onto the black hole's accretion disk to trigger another outburst.
