X-Ray Telescope Captures Huge Black Hole
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By PAUL RECER, AP Science Writer
SEATTLE - The supermassive black hole at the center of the Milky Way flares
with intense eruptions every day as it gobbles up nearby gas, dust and
objects. But the most sensitive X-ray images ever taken show it is starved and
puny compared with black holes in other galaxies.
Astronomers using the Chandra X-ray telescope have captured images of intense
flares streaking from the center of the Milky Way and said the violence comes
from a supermassive black hole living on matter.
The study also suggests that the Milky Way's black hole is underfed when
compared with the supermassive black hole of other galaxies, said Frederick K.
Baganoff of the Massachusetts Institute of Technology (news - web sites). He
presented his study Monday at the national meeting of the American
Astronomical Society.
Baganoff said the Milky Way's black hole spends much of its time quietly
emitting X-rays about equal to all the energy streaming from the sun. But at
least once a day the black hole suddenly flares, erupting with X-ray bursts 10
to 45 times more powerful than all the sun's energy. Then it settles down
again, all within 90 minutes or less.
"No other supermassive black hole has shown this behavior," Baganoff said.
"These frequent, short-duration flares are unique to the supermassive black
hole in our galaxy."
Baganoff said the black hole may be starved because nearby star explosions in
the past have blown away most of the gas and dust that would feed the black
hole.
"Although it appears to snack often, this black hole is definitely on a severe
diet," he said.
The black hole swallows mass equal to about one-billionth of the sun every
year, but the mass available in the Milky Way suggests it should be sucking in
about 100 times more matter.
The Chandra telescope also detected X-rays streaming from clouds and streaks
of heated matter that may be the remnants of past meals. As matter is sucked
into black hole, some of it is accelerated to near the speed of light and
heated to 2 million degrees, flying off away from the galaxy center.
Streaks of X-rays just over one light year from the center was probably
ejected recently, but other X-rays come from matter that may be been sent
streaking away more than 10,000 years ago.
Most galaxies the size of the Milky Way are thought to contain supermassive
black holes that form a gravitation center orbited by billions of stars.
Black holes are so dense with mass that their gravity will not allow anything,
even light, to escape. They cannot be seen directly because they emit no
radiation, but their immense gravity causes matter to spiral at high speeds
toward the center, heating the material to millions of degrees and to radiate
energy.
The Milky Way's black hole is thought to have about 3 million times the mass
of the sun.
Bruce Margon, an astronomer at the Space Telescope Science Institute, said the
Chandra X-ray study suggests the Milky Way's black hole is a "messy eater,"
expelling crumbs from past meals in the form of matter streaking away at high
speed. The studies give fundamental new understanding about the behavior and
history of black holes in general, he said.
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American Astronomical Society: www.aas.org