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October
26, 1999: NASA's Chandra X-ray Observatory has made an extraordinary
image of Centaurus A, a nearby galaxy noted for its explosive
activity. The image shows X-ray jets erupting from the center
of the galaxy over a distance of 25,000 light years. Also detected
are a group of X-ray sources clustered around the nucleus, which
is believed to harbor a supermassive black hole. The X-ray jets
and the cluster of sources may be a byproduct of a titanic collision
between galaxies several hundred million years ago. "This image is great," said Dr. Ethan Schreier of
the Space Telescope Science Institute, "For twenty years
we have been trying to understand what produced the X rays seen
in the Centaurus A jet. Now we at last know that the X-ray emission
is produced by extremely high energy electrons spiraling around
a magnetic field." Schreier explained that the length and
shape of the X-ray jet pinned down the source of the radiation.
The entire length of the X-ray jet is comparable to the diameter
of the Milky Way Galaxy. |
Above: Centaurus A as viewed in four different spectra. The brilliant jet so visible in the x-ray is perpendicular to the apparent plane of the galaxy in visible or infrared. See the Chandra X-Ray Observatory Center's What Do These Images Tell Us page for more information. Astronomers have accumulated evidence with optical and infrared
telescopes that Centaurus A collided with a small spiral galaxy
several hundred million years ago. This collision is believed
to have triggered a burst of star formation and supplied gas
to fuel the activity of the central black hole. |
The Chandra X-ray image of Centaurus A, made with the High Resolution Camera, shows a bright source in the nucleus of the galaxy at the location of the suspected supermassive black hole. The bright jet extending out from the nucleus to the upper left is due to explosive activity around the black hole that ejects matter at high speeds from the vicinity of the black hole. A "counter jet" extending to the lower right can also be seen. This jet is probably pointing away from us, which accounts for its faint appearance. |
One of the most intriguing features of supermassive black holes is that they do not suck up all the matter that falls within their sphere of influence. Some of the matter falls inexorably toward the black hole, and some explodes away from the black hole in high-energy jets that move at near the speed of light. The presence of bright X-ray jets in the Chandra image means that electric fields are continually accelerating electrons to extremely high energies over enormous distances. Exactly how this happens is a major puzzle that Chandra may help to solve. Dr. Stephen Murray of the Harvard-Smithsonian Center for Astrophysics is the principal investigator for the High Resolution Camera. NASA's Marshall Space Flight Center in Huntsville, AL, manages the Chandra program. TRW, Inc., Redondo Beach, CA, is the prime contractor for the spacecraft. The Smithsonian's Chandra X-ray Center controls science and flight operations from Cambridge, MA. |
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