ALBUQUERQUE, N.M. - The most massive black holes share much in common with their puniest cousins, according to a new study that found the first direct evidence for the source of energetic jets shooting out in two opposite directions from one of Nature's most impressive gravity wells.Black holes swallow material so efficiently that even light cannot escape their clutches, and so they cannot be seen directly. But their surroundings are not completely efficient, and a good chunk of the material that swirls in toward a black hole is converted into X-rays and other energy that is cast back into space.
These byproducts allow astronomers to infer the existence of black holes.
Over the past eight years, stellar black holes weighing only as much as a few Suns have been found to direct some of their converted energy out along two narrow jets that travel in opposite directions along the objects' axis of rotation. Researchers connected these jets, detected in radio waves, to their source: the so-called accretion disk of material spiraling inward.
Theorists expected that supermassive black holes, which can pack the mass of billions of Suns into a small space at the center of a galaxy, should be using the same mechanism to produce their jets.
They do.
"This is the first direct, observational evidence of what we had suspected," said Boston University's Alan Marscher, who detailed his team's study here at the 200th meeting of the American Astronomical Society.
Some supermassive black holes, particularly in the distant and thus ancient universe, are found to be so actively consuming matter that their X-rays are bright well across time and space. These quasars, as they are called, can be brighter than thousands of ordinary galaxies.
In one quasar called 3C120, which is relatively nearby at just 450 million light-years away, Marscher and his colleagues detected jets of particles moving at 98 percent the speed of light. The emissions were detected in the form of radio waves by the National Science Foundation's Very Long Baseline Array.
The researchers used NASA's Rossi X-ray Timing Explorer satellite to determine that the radio emissions followed periods where the X-ray emissions from the disk were dimmer. They suspect the black hole is suddenly flushing material from one part of the system to another.
Over a three-year period, the team noted a series of X-ray dips, roughly every 10 months, each followed by a spurt of radio emissions.
"What we are likely seeing is the inner part of the accretion disk becoming unstable and suddenly plunging into the black hole," Marscher said.
The results are published in the June 6 issue of the journal Nature.
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