NANOGrav_PTA_GWB_15yr_wide (IMAGE) SETI Institute Caption Artist’s interpretation of an array of pulsars being affected by gravitational ripples produced by a supermassive black hole binary in a distant galaxy. Credit Aurore Simonnet for the NANOGrav Collaboration. Usage Restrictions With credit License Original 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.