Chandra Catches Milky Way Monster Snacking
This false-color image shows the central region of our Milky Way
Galaxy as seen by Chandra. The bright, point-like source at the
center of the image was produced by a huge X-ray flare that
occurred in the vicinity of the supermassive black hole at the center
of our galaxy.
For the first time astronomers have detected material
being consumed by the supermassive black hole in our own
backyard. A violent, rapid X-ray flare,
captured by NASA's
Chandra X-ray Observatory, has been observed from the
direction of the supermassive black hole that resides at the
center of our Milky Way Galaxy.
A team of scientists, led by Fredrick K. Baganoff of the
Massachusetts Institute of Technology (MIT) in Cambridge,
detected a sudden X-ray flare while observing Sagittarius A*,
a source of radio emission believed to be associated with the
black hole at the center of our Galaxy.
"This is extremely exciting because it's the first time we
have seen our own neighborhood supermassive black hole devour
a chunk of material," Baganoff said. "It's as if the material
there sent us a postcard before it fell in."
In a few minutes, the source brightened dramatically,
eventually reaching a level 45 times brighter than before the
flare. After about three hours, the X-ray intensity rapidly
declined to the pre-flare level. "The rapid rise and fall of
the X-rays from this outburst are compelling evidence that
the X-ray emission is coming from matter falling into a
supermassive black hole, confirming that it is powered by the
same accretion process as quasars and other active galactic
nuclei," said Baganoff.
Baganoff added that the data also provide the best look yet
at the area just outside this event horizon, the surface of
"no return" for matter or light falling into a black hole.
Studies of the central region of our Milky Way Galaxy in the
infrared and radio wavebands indicate the presence of a
large, dark object, presumably a supermassive black hole,
having the mass of about 3 million suns. The faintness of
Sagittarius A* at all wavelengths, especially in X-rays, has
puzzled scientists who expected that the infalling matter
should shine more brightly on its way in, and this has left
some room for doubt.
The latest precise Chandra observations of the crowded
galactic center region have dispelled that doubt. Given the
extremely accurate position, it is highly unlikely that the
flare is due to an unrelated contaminating source such as an
X-ray binary system.
"The rapidity of the variations in X-ray intensity indicate
that we are observing material that is as close to the black
hole as the Earth is to the Sun," said Gordon Garmire of
Pennsylvania State University, University Park, principal
investigator of the Advanced CCD Imaging Spectrometer (ACIS),
which was used in these observations.
"It's truly remarkable that we could identify and track this
flare in such a crowded region of space," said Mark Bautz of
MIT. "This discovery would not have been possible without the
resolution and sensitivity of Chandra and the ACIS
Baganoff and his colleagues first observed Sagittarius A* with ACIS
on Sept. 21, 1999, and again on Oct. 26-27, 2000. The X-ray flare was
detected in the second observation.
Other members of the team include: Niel Brandt, George
Chartas, Eric Feigelson and Leisa Townsley, all from Penn
State; Yoshitomo Maeda, Institute of Space and Astronautical
Science, Japan; Mark Morris, UCLA; George Ricker, MIT; and
Fabian Walker, California Institute of Technology, Pasadena.