X-ray telescope spots massive black holes in early universe
06/15/2011 02:40 PM Filed in: Space News | Space Science
By WILLIAM HARWOOD
CBS News
Taking what amounts to a 45-day time exposure, NASA's Chandra X-Ray Observatory has detected numerous massive black holes lurking in the dusty hearts of galaxies that formed within a billion years of the big bang birth of the cosmos, astronomers announced Wednesday.
The observations, based on the deepest X-ray image ever made, are the first direct evidence showing massive black holes were common in the early universe, growing in concert with their host galaxies much more rapidly than previously thought.
"What we've seen are baby black holes in very young galaxies at the dawn of the universe," Kevin Schawinski, an astrophysicist at Yale University, told reporters. "These black holes are feeding on material, gas, at the centers of these galaxies and they'll continue to grow through adolescence and adulthood.
"They may also merge with black holes from other galaxies as their hosts merge and they may end up accumulating a hundred or even a thousand times the mass that they have in the early universe until they end up at the centers of nearby galaxies."
Unlike relatively rare quasars -- super-massive black holes with masses more than a billion times that of the sun -- the black holes detected by Chandra in a sampling of 200 remote galaxies are a hundred times fainter and a thousand times less massive. But the data suggest baby black holes are present in at least 30 percent of the galaxies observed and possibly all of them.
The black holes were detected by capturing X-rays emitted as gas and dust, accelerated to relativistic velocities, were consumed. The Hubble Space Telescope captured faint images of galaxies in the Chandra target field, but because of the obscuring gas and dust, only X-rays made it out into open space and, eventually, Earth.
Schawinski said astronomers already suspected a direct relationship between galaxy formation and super massive black holes. Virtually every galaxy seen appears to harbor a massive black hole, including a 4-million-solar-mass hole at the center of Earth's Milky Way.
"Not only do galaxies contain black holes at the center, but galaxies and black holes seem to grow together," he said. "Big galaxies have big black holes at their center, small galaxies have small black holes. We believe they have this funamental symbiotic relationship (and) the growth of one regulates the growth of the other in a kind of feedback loop.
"What our observations of galaxies in the very early universe tell us is that these very early young galaxies at the dawn of the universe and their growing baby black holes already have some sort of deep, fundamental connection between them. They were already growing together, and so this chicken-and-egg problem of what was there first, the galaxy or the black hole, has been pushed all the way to the edge of the universe."
Yale astronomer Priya Natarajan said there are two schools of thought on how black holes might have formed in the early universe. One model views the black holes as the end state of a massive star's evolution, the result of supernova explosions and subsequent growth, while the other considers them the result of collapsing clouds of gas.
The Chandra observations seem to support the latter scenario, "that very, very early in the universe, less than a billion years after the big bang ... there appears to be an intimate connection between the properties of these growing black holes and the galaxies in which they sit," Natarajan said.
The Chandra observations are not a "baby step forward," she said. "It's a large leap in our understanding of how baby black holes formed."
CBS News
Taking what amounts to a 45-day time exposure, NASA's Chandra X-Ray Observatory has detected numerous massive black holes lurking in the dusty hearts of galaxies that formed within a billion years of the big bang birth of the cosmos, astronomers announced Wednesday.
The observations, based on the deepest X-ray image ever made, are the first direct evidence showing massive black holes were common in the early universe, growing in concert with their host galaxies much more rapidly than previously thought.
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| Merging a visible light image from the Hubble Space Telescope and an X-ray image from the Chandra X-ray Observatory, astronomers detect numerous massive black holes at the cores of galaxies within a billion years of the birth of the universe. (Credit: NASA) |
"What we've seen are baby black holes in very young galaxies at the dawn of the universe," Kevin Schawinski, an astrophysicist at Yale University, told reporters. "These black holes are feeding on material, gas, at the centers of these galaxies and they'll continue to grow through adolescence and adulthood.
"They may also merge with black holes from other galaxies as their hosts merge and they may end up accumulating a hundred or even a thousand times the mass that they have in the early universe until they end up at the centers of nearby galaxies."
Unlike relatively rare quasars -- super-massive black holes with masses more than a billion times that of the sun -- the black holes detected by Chandra in a sampling of 200 remote galaxies are a hundred times fainter and a thousand times less massive. But the data suggest baby black holes are present in at least 30 percent of the galaxies observed and possibly all of them.
The black holes were detected by capturing X-rays emitted as gas and dust, accelerated to relativistic velocities, were consumed. The Hubble Space Telescope captured faint images of galaxies in the Chandra target field, but because of the obscuring gas and dust, only X-rays made it out into open space and, eventually, Earth.
Schawinski said astronomers already suspected a direct relationship between galaxy formation and super massive black holes. Virtually every galaxy seen appears to harbor a massive black hole, including a 4-million-solar-mass hole at the center of Earth's Milky Way.
"Not only do galaxies contain black holes at the center, but galaxies and black holes seem to grow together," he said. "Big galaxies have big black holes at their center, small galaxies have small black holes. We believe they have this funamental symbiotic relationship (and) the growth of one regulates the growth of the other in a kind of feedback loop.
"What our observations of galaxies in the very early universe tell us is that these very early young galaxies at the dawn of the universe and their growing baby black holes already have some sort of deep, fundamental connection between them. They were already growing together, and so this chicken-and-egg problem of what was there first, the galaxy or the black hole, has been pushed all the way to the edge of the universe."
Yale astronomer Priya Natarajan said there are two schools of thought on how black holes might have formed in the early universe. One model views the black holes as the end state of a massive star's evolution, the result of supernova explosions and subsequent growth, while the other considers them the result of collapsing clouds of gas.
The Chandra observations seem to support the latter scenario, "that very, very early in the universe, less than a billion years after the big bang ... there appears to be an intimate connection between the properties of these growing black holes and the galaxies in which they sit," Natarajan said.
The Chandra observations are not a "baby step forward," she said. "It's a large leap in our understanding of how baby black holes formed."