SDSS J1056+5516: A Triple AGN or an SMBH Recoil Candidate?
Abstract
We report the discovery of a kiloparsec-scale triple supermassive black hole system at z=0.256: SDSS J1056+5516, discovered by our systematic search for binary quasars. The system contains three strong emission-line nuclei, which are offset by <250~ km~s-1 and by 15-18 kpc in projected separation, suggesting that the nuclei belong to the same physical structure. The system includes a tidal arm feature spanning 100 kpc in projected distance at the systems' redshift, inhabiting an ongoing or recent galaxy merger. Based on our results, such a structure can only satisfy one of the three scenarios; a triple supermasive black hole (SMBH) interacting system, a triple AGN, or a recoiling SMBH. Each of these scenarios is unique for our understanding of the hierarchical growth of galaxies, AGN triggering, and gravitational waves.
Turn this paper into a lesson
ArcXiv compiles a structured reading guide from this paper's metadata: plain-English importance, contributions, prerequisite concepts, which sections to read first, flashcards, and a quiz. Grounded in the abstract, never invented.