- Astronomers discover gamma ray-emitting blobs above and below the galaxy's center. - The Milky Way is blowing bubbles of cosmic proportions. November 13, 2010 - (CERES TV News) -- Twin bubbles of gamma ray--emitting gas, each the size of a small galaxy, sit above and below the center of the Milky Way like the ends of a giant dumbbell, astronomers have discovered. Douglas Finkbeiner of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass., and his colleagues analyzed data from NASA's Fermi Gamma-ray Space Telescope to find the bubbles, which may have been generated in the galaxy's core by a long-ago burst of star formation or by a past eruption from the supermassive black hole believed to lie there. Finkbeiner described the findings, which will appear in an upcoming Astrophysical Journal, during a November 9 telephone briefing. The bubbles aren't readily apparent because a high-energy gamma-ray fog, discovered by Finkbeiner and his colleagues last year, fills the sky, mainly due to high-speed electrons and protons interacting with light and interstellar gas in the Milky Way. But when Finkbeiner and his colleagues subtracted the fog from the Fermi telescope's data they uncovered the two giant lobes. Far above the plane of the galaxy it's easy to see the sharp edges of the structures, but closer to the plane, where the gamma-ray emission isn't as bright as the radiation from the Milky Way's disk, it's more difficult to determine if the feature has the hourglass shape characteristic of two connected bubbles, cautioned Gregory Dobler of the University of California, Santa Barbara, who worked with Finkbeiner on an earlier map of the gamma-ray fog. Some models give a geometry that looks like an hourglass while others look more like an oval, Dobler said. Depending when the bubbles were generated, each lobe could hold as much energy as 100,000 supernovas release, Finkbeiner said. Each bubble has a diameter of about 25,000 light-years, roughly the length of the Large Magellanic Cloud, a satellite galaxy of the Milky Way. In sifting through data taken with other telescopes, hints of the outlines of the bubbles appear as both low-energy X-rays and microwaves, Finkbeiner noted. © 2010 CERES TV Science News [more info at]: http://www.cerestv.com [e-mail]: news@cerestv.com For further information: Teléf.+34 983 457460 • Fax: +34 983 233387 Valladolid - (Spain)
