Binary black holes •
EGSD2 J142033.66 525917.5 core black holes — galaxy hosting a dual AGN •
OJ 287 core black holes — a
BL Lac object with a candidate binary supermassive black hole core system •
PG 1302-102 – the first binary-cored quasar — a pair of supermassive black holes at the core of this quasar •
SDSS J120136.02+300305.5 core black holes — a pair of supermassive black holes at the centre of this galaxy In addition, the signal of several binary black holes merging into a single black hole and in so doing producing
gravitational waves have been observed by the
LIGO instrument. These are listed above in the section
Black holes detected by gravitational wave signals.
Trinary black holes As of 2014, there are 5 triple black hole systems known. •
SDSS J150243.09+111557.3 (SDSS J1502+1115) core black holes — the three components are distant tertiary J1502P, and the close binary pair J1502S composed of J1502SE and J1502SW •
2MASX J10270057+1749001 (SDSS J1027+1749) core black holes ==See also==