Mystery Galactic Gamma-ray ‘Bubbles’ Defy Explanation

Aug 12, 2014

By Ian O’Neill

In 2010, astronomers announced the discovery of two vast — and very mysterious — bubbles of gamma-ray emissions towering above and below our galaxy’s disk. Four years on, after oodles of analysis, the source of these bubbles is as mysterious as ever.

The scale of these gamma-ray structures is truly mind-blowing. Apparently originating directly from the galactic core, the two lobes extend tens of thousands of light-years into intergalactic space. They both generate gamma-ray radiation at an astonishing luminosity, “like two 30,000-light-year-tall incandescent bulbs screwed into the center of the galaxy,” according to a Stanford University news release.

The discovery was made by NASA’s Fermi Gamma-Ray Observatory that orbits the Earth away from our planet’s gamma-ray absorbing atmosphere. Without Fermi, we wouldn’t have even been aware of these giant structures.

Since their discovery by Fermi’s Large Area Telescope (LAT), it was assumed that an ancient eruption by the Milky Way’s supermassive black hole may have energized galactic matter, inflating these two energetic bubbles. But since astronomers have been studying the nature of these features, their origin is as foggy as ever.

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