Chandra reveals X-ray jet in nearby galaxy

October 26, 1999
Web posted at: 2:11 p.m. EDT (1811 GMT)

(CNN) -- An image of the nearby galaxy Centaurus A captured by the Chandra X-ray Observatory reveals what may be the after-effects of a titanic collision between galaxies several hundred million years ago, NASA said Tuesday.

The image shows X-ray jets erupting from the center of the galaxy over a distance of 25,000 light years -- a length comparable to the diameter of the Milky Way Galaxy.

Also detected are a group of X-ray sources clustered around the nucleus, which is believed to harbor a supermassive black hole, NASA said in a statement.

"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."

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Schreier said the length and shape of the X-ray jet pinned down the source of the radiation.

Other features of the image excite scientists. "Besides the jets, one of the first things I noticed about the image was the new population of sources in the center of the galaxy," said Dr. Christine Jones from the Harvard-Smithsonian Center for Astrophysics . "They are grouped in a sphere around the nucleus, which must be telling us something very fundamental about how the galaxy, and the supermassive black hole in the center, were formed."

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.

At a distance of 11 million light years from Earth, Centaurus A has been a favorite of astronomers because it is the nearest "active" galaxy.

Such galaxies are noted for their explosive activity, presumed to be the result of a massive black hole in the center.

The energy output due to the black hole can affect the appearance of the entire galaxy, NASA said.