γ-rays from the Edge of a Supermassive Black Hole
Reference: V. A. Acciari et al. (The VERITAS Collaboration), Science, 325, 444, 2009
Abstract , Full text version
ArXiv version: ArXiV:0908.0511
Contact person: Matthias Beilicke
High-resolution radio and gamma-ray observations reveal the site of relativistic particle acceleration in the galaxy M87
An international collaboration of 390 scientists reports the discovery of an outburst of very-high-energy (VHE) gamma radiation from the giant radio galaxy Messier 87 (M87), accompanied by a strong rise of the radio flux measured from the direct vicinity of its super-massive black hole. The combined results give first experimental evidence that particles are accelerated to extremely high energies of tera electron Volt (one electron Volt is the energy an electron or proton gains when it is accelerated by a voltage of one Volt) in the immediate vicinity of a supermassive black hole and then emit the observed gamma rays. The gamma rays have energies a trillion times higher than the energy of visible light. The large collaborative effort involved three arrays of 12-meter to 17-meter telescopes (VERITAS, MAGIC and H.E.S.S. ) that detect very high-energy gamma rays and the Very Long Baseline Array (VLBA) that detects radio waves with high spatial precision. The results will appear in the July 2 Science Express, the advance online publication of the journal Science.
"We had scheduled gamma-ray observations of M87 in a close cooperative effort with the three major gamma-ray observatories VERITAS, H.E.S.S. and MAGIC, and we were lucky that an extraordinary gamma-ray flare happened just when the source was observed with the VLBA and its impressive spatial resolving power," says Beilicke, working with the Very Energetic Radiation Imaging Telescope Array System (VERITAS). "Only combining the high-resolution radio observations with the VHE gamma-ray observations allowed us to locate the site of the gamma-ray production," says Craig Walker, staff scientist at the National Radio Astronomy Observatory in Socorro, New Mexico.
All figures from paper (click to get full size image):