Southern Pinwheel galaxy (IMAGE) Rochester Institute of Technology Caption RIT researchers propose that the outer gas disk of spiral galaxies could be teeming with black holes that emit gravitational waves as they collide. Shown here is the Southern Pinwheel galaxy seen in ultraviolet light and radio wavelengths. The radio data, colored here in red, reveal the boondocks of the galaxy where orbiting black holes might exist. Credit NASA/JPL-Caltech/VLA/MPIA 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.