The Chandra X-ray Observatory has captured the sharpest images yet of a mysterious X-ray-emitting ridge that lurks within the center of our Milky Way galaxy.
The images promise to solve a 30 year-old mystery of how this zone of ultra high-energy radiation came to exist within a relatively mild interior, said the lead scientist for the project, Farhad Zadeh of Northwestern University in Illinois.
Zadeh presented his findings today at the American Astronomical Society meeting in Washington.
"Sometimes science does deal with simple mechanisms," said Zadeh. "Using existing theoretical work, we have shown that dramatic events are not necessary to explain the X-ray galactic ridge."
The Chandra data was 10 times clearer than any previous X-ray observations of the zone, and was able to find a new entity within the hot X-ray disc. It turns out that Chandra helped clarify that a less energetic radio emission is also present.
This led Zadeh and his team to theorize that low-energy cosmic rays must have bombarded, and thus heated, a cloud of cold gas 1 million times the mass of the Sun. The collision would have produced the X-ray emission of the galactic ridge.
Earlier explanations of the ridges origin have focused on rather dramatic scenarios, such as 100 million-degree gases being constantly replenished by an unknown source, or an energetic explosion at the galactic center that may have occurred 300 years ago.
"We are now offering a simpler mechanism to explain the mystery," he said.
Besides being easier to understand, the results also help explain the prolific star formation in the central regions of the Galaxy.
"The bombardment of the giant clouds by low-energy cosmic rays increases their temperature and degree of ionization, two key parameters that determine the ability of interstellar clouds to form stars," explained another of the project's scientists, Mark Wardle of the University of Sydney, Australia.
But although the pieces of the galactic puzzle seem to be falling into place, the team studied a portion of the X-ray zone that represents just a millionth of the entire ridge. Yet the team believes their study tells a great deal about the bigger picture.
"We believe our images are a very good representation of what is happening in the entire X-ray galactic ridge," said Zadeh. "The data provides new evidence for the origin of the ridge and its X-ray emission, evidence which has implications for the origins of high-energy activity in our galaxy as well as other galaxies."
Headline: More Information:
advertisement
