Startled astronomers said Tuesday they had discovered two massive bubbles of gamma-ray energy extending 25,000 light-years above and below the plane of the Milky Way galaxy like a squat hourglass.
"They're big, they're sharp-edged and they contain a lot of energy," astrophysicist Douglas Finkbeiner of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass., said in a news conference. Finkbeiner led a team that used data from NASA's 2-year-old orbiting Fermi Gamma-ray Space Telescope to discover the bubbles hiding behind a fog of gamma rays.
That fog occurs when particles moving at or near the speed of light interact with interstellar gas.
"My first response when I saw these figures was, 'Wow!' " astronomer David Spergel of Princeton University said at the news conference. Spergel, who was not involved in the research, added that "we think we know a lot about our own galaxy," and yet the bubbles, which are almost as big as the galaxy itself, were totally unexpected.
Researchers do not yet know what produced the bubbles, but the fact that they appear to have relatively sharp edges suggests that they were produced in a single event. Finkbeiner said that would have required the rapid release of energy equivalent to about 100,000 supernovae, or exploding stars.