Milky Way's dark center

Physics (Oct. 9) -- The Fermi Gamma-Ray Space Telescope recently detected unexpectedly intense gamma rays coming from the center of the Milky Way, where a supermassive black hole is believed to exist. Brian Fields, Stuart Shapiro and Jessie Shelton at Illinois have calculated the intensity of gamma-ray radiation that such a spike could generate. They show that, under some of the most plausible scenarios, the expected signal would exceed by far that observed by Fermi. This leads to two possible conclusions: either the emission is not due to dark matter, or the Galaxy’s center is different than that envisioned by the simplest galactic models.