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Black holes may scatter “seeds of life” through cosmos
April 22, 2007
Courtesy Harvard-Smithsonian Center for Astrophysics
and World Science staff
Black holes aren’t the all-consuming monsters they’re often portrayed as, new research has found: instead, warm gas escaping from the clutches of giant black holes could be one source of the chemical elements used for life. NGC 4051 (Courtesy CfA)
Black holes are cosmic objects consisting of tremendous amounts of
material packed into a tiny space. The huge quantity of matter exerts a gravitational pull so strong that it sucks in everything nearby, including light.
Immediately after the Big Bang explosion that astronomers believe gave birth to the universe, the cosmos is thought to have contained only hydrogen and helium, the lightest chemical elements.
Heavier elements had to be cooked up in stars, then scattered to be incorporated in other stars and their planets. Black holes may have helped spread those elements across the cosmos, scientists now say.
Black holes tend to suck in clouds of gas that surround them, but not all gas falls in. Until
the gas crosses a boundary known as the event horizon, it can still escape if it is heated, that is energized,
enough.
“One of the big questions in cosmology is how much influence massive black holes exert on their surroundings,” said Martin Elvis of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass. “This research helps answer that question.” A group of astronomers including Elvis found that hot winds from giant black holes in the centers of galaxies may blow heavy elements like carbon and oxygen into the vast space between galaxies.
Most galaxies are thought to contain a “supermassive” black hole at their center. The research team, led by Yair Krongold of the Universidad Nacional Autonoma de Mexico, studied such an object at the center of a galaxy called NGC 4051. They found that gas was escaping from much closer to the black hole than previously thought.
The outflow source was about 2,000 times further from the black hole center than the distance
from there to its event horizon—a length called the Schwarzschild radius
that is about four million miles for this black hole. The team also estimated the fraction of gas that avoided being swallowed; this turned out to be smaller than earlier studies suggested.
“We calculate that between two to five percent of the accreting material is flowing back out,” said team member Fabrizio Nicastro of the Center for Astrophysics.
Winds from black holes have been clocked at speeds of up to four million miles per hour, researchers said. So over thousands of years, elements such as carbon and oxygen in those winds can travel huge distances; they eventually become part of great clouds of gas and dust, called nebulae, that form new stars and planets.
The research, which used data from the European Space Agency’s XMM-Newton satellite, is reported in the April 20 issue of the research publication
Astrophysical Journal.
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Black holes aren’t the all-consuming monsters they’re often portrayed as, new research has found: instead, warm gas escaping from the clutches of giant black holes could be one source of the chemical elements used for life. Black holes are cosmic objects in which a tremendous amount of matter is packed into a tiny space. The huge quantity of matter exerts a gravitational pull so strong that it sucks in everything nearby, including light. Immediately after the Big Bang explosion that astronomers believe gave birth to the universe, the cosmos is thought to have contained only hydrogen and helium, the lightest chemical elements. Heavier elements had to be cooked up in stars, then scattered to be incorporated in other stars and their planets. Black holes may have helped spread those elements across the cosmos, scientists now say. Black holes tend to suck in clouds of gas that surround them, but not all gas falls in. Until it crosses a boundary known as the event horizon, it can still escape if it is heated, that is energized, enough.”One of the big questions in cosmology is how much influence massive black holes exert on their surroundings,” said Martin Elvis of the Harvard-Smithsonian Center for Astro physics in Cambridge, Mass. “This research helps answer that question.” A group of astronomers including Elvis found that hot winds from giant black holes in the centers of galaxies may blow heavy elements like carbon and oxygen into the vast space between galaxies. Most galaxies are thought to contain a “supermassive” black hole at their center. The research team, led by Yair Krongold of the Universidad Nacional Autonoma de Mexico, studied such an object at the center of a galaxy called NGC 4051. They found that gas was escaping from much closer to the black hole than previously thought. The outflow source was about 2,000 times further from the black hole center than the distance to its event horizon—a length called the Schwarzschild radius, which is about four million miles for this black hole. The team also estimated the fraction of gas that avoided being swallowed; this turned out to be smaller than earlier studies suggested. “We calculate that between 2 to 5 percent of the accreting material is flowing back out,” said team member Fabrizio Nicastro of the Center for Astro physics. Winds from black holes have been clocked at speeds of up to four million miles per hour, researchers said. So over thousands of years, elements such as carbon and oxygen in those winds can travel huge distances; they eventually become part of great clouds of gas and dust, called nebulae, that form new stars and planets. The research, which used data from the European Space Agency’s XMM-Newton satellite, is reported in the April 20 issue of the research publication Astro physical Journal.