Blazar (IMAGE) DOE/SLAC National Accelerator Laboratory Caption Illustration of a blazar, a powerful object that produces beams of gamma rays when material spirals into a massive black hole. Blazars are the most common extraterrestrial sources of high-energy gamma rays detected by the Fermi Gamma-ray Space Telescope. Credit M. Weiss/CfA Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.