NASA's Swift clicks pics of X-ray action at Milky Way's core

Recent observations by NASA's Swift spacecraft have provided scientists a unique glimpse into the activity at the center of Milky Way galaxy and led to the discovery of a rare celestial entity which may help them test predictions of Albert Einstein's theory of general relativity.

This X-ray image of the galactic center merges Swift XRT observations through 2013. Sgr A* is at center. Low-energy X-rays (300 to 1,500 electron volts) are shown in red, medium-energy (1,500 to 3,000 eV) in green, and high-energy (3,000 to 10,000 eV) in blue. The total exposure time is 12.6 days.

Swift's seven-year campaign to monitor the center of the Milky Way has doubled the number of images available to scientists of bright X-ray flares occurring at the galaxy's central black hole, dubbed Sagittarius A* (Sgr A*), which sits in the center of the Milky Way's innermost region, 26,000 light-years away in the direction of the constellation Sagittarius.

Nathalie Degenaar, principal investigator on the Swift galactic center campaign and an astronomer at the University of Michigan in Ann Arbor, said that given its size, this supermassive black hole is about a billion times fainter than it could be, asserting that though it's sedate now, it was quite active in the past and still regularly produces brief X-ray flares today.

To date, Swift's XRT has detected six bright flares during which the black hole's X-ray emission was as much as 150 times brighter for a couple of hours.

These new detections enabled the team to estimate that similar flares occur every five to 10 days. Scientists will look at differences between the outbursts to decipher their physical nature.