A search of a data set of light curves for 247,000 known, spectroscopically confirmed quasars with a temporal baseline of about 9 years reveals a strong, smooth periodic signal in the optical variability of quasar PG 1302−102 with a mean observed period of 1,884 ± 88 days, indicating a possible supermassive black-hole binary.
- Matthew J. Graham
- S. G. Djorgovski
- Eric Christensen