Blazars show up when one of the emitted jets in the active galactic nucleus is pointing directly towards the Earth. The researchers present evidence that it is in fact the precession of the jet source, either caused by the presence of a second massive black hole close to the primary one or a warped accretion disk around a single black hole, that is responsible for the observed variability in blazars.
For details of the published study, including contacts and other background information, see the Max Planck Institute's press release HERE.
Original Paper in The Astrophysical Journal is available on:
Britzen et al.: “Precession-induced Variability in AGN Jets and OJ 287”, in The Astrophysical Journal, 951, 106. DOI: 0.3847/1538-4357/accbbc
https://doi.org/10.3847/1538-4357/accbbc