NGC 4455 (IMAGE) Scuola Internazionale Superiore di Studi Avanzati Caption Acceleration as a function of radius in NGC 4455, one of the studied galaxies. Credit Di Paolo et al. modified from survey SDSS9. Usage Restrictions Credits should be mentioned 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.