Sunday, October 29, 2006

Gamma Rays From M87

Astrophysicists report the discovery of fast variability in very-high-energy (VHE) gamma rays from the giant elliptical galaxy M 87. The detection of these gamma-ray photons - with energies more than a million million times the energy of visible light - from one of the most famous extragalactic objects on the sky is remarkable, though long-expected given the many potential sites of particle acceleration (and thus gamma-ray production) within M 87.

Much more surprising was the discovery of drastic gamma-ray flux variations on time-scales of days. These results, for the first time, exclude all possible options for sites of gamma-ray production, except for the most exciting and extraordinary one: the immediate vicinity of the super-massive black hole which is located in the centre of M 87

Link: Science Express, October 26, 2006.