Magazine article Science News

Milky Way Blows Cosmic Bubbles: Gamma-Ray Blobs Emanate from the Center of the Galaxy

Magazine article Science News

Milky Way Blows Cosmic Bubbles: Gamma-Ray Blobs Emanate from the Center of the Galaxy

Article excerpt

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 colleagues analyzed data from NASA's Fermi Gammaray Space Telescope to find the bubbles. Finkbeiner described the findings, which appear in the Dec. 1 Astrophysical Journal, during a November 9 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 galaxy. But when Finkbeiner and his colleagues subtracted the fog from the Fermi telescope's data, they uncovered the two giant lobes.

Depending on when the bubbles were generated, each lobe could hold the energy released by 100,000 supernovas, Finkbeiner said. Each has a diameter of about 25,000 light-years, roughly the length of the Large Magellanic Cloud, a satellite galaxy of the Milky Way.

[ILLUSTRATION OMITTED]

One possible source of the bubbles is a proposed wave of star birth at the galaxy's center millions of years ago. If a large population of massive stars were born all at the same time, their explosive deaths could have created enough energy, in the form of energetic electrons or protons, to power the bubbles and cause them to glow with gamma rays. …

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