Dark Matter (IMAGE) DOE/SLAC National Accelerator Laboratory Caption One potential source of cosmic gamma rays could be dark matter. A leading theory predicts the mysterious stuff is made of weakly interacting massive particles, or WIMPs, which could annihilate each other in a flash of gamma rays when they collide. Credit Greg Stewart/SLAC National Accelerator Laboratory 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.