## [1011.2647] A Very Close Binary Black Hole in a Giant Elliptical Galaxy 3C 66B and its Black Hole Merger

Authors: Satoru Iguchi, Takeshi Okuda, Hiroshi Sudou

Date: 11 Nov 2010

Abstract: Recent observational results provide possible evidence that binary black holes (BBHs) exist in the center of giant galaxies and may merge to form a supermassive black hole in the process of their evolution. We first detected a periodic flux variation on a cycle of $93\pm1$ days from the 3-mm monitor observations of a giant elliptical galaxy \object{3C 66B} for which an orbital motion with a period of $1.05\pm0.03$ years had been already observed. The detected signal period being shorter than the orbital period can be explained by taking into consideration the Doppler-shifted modulation due to the orbital motion of a BBH. Assuming that the BBH has a circular orbit and that the jet axis is parallel to the binary angular momentum, our observational results demonstrate the presence of a very close BBH that has the binary orbit with an orbital period of $1.05\pm0.03$ years, an orbital radius of $(3.9\pm1.0) \times 10ˆ{-3}$ pc, an orbital separation of $(6.1ˆ{+1.0}_{-0.9}) \times 10ˆ{-3}$ pc, the larger black hole mass of $(1.2ˆ{+0.5}_{-0.2}) \times 10ˆ9$ $M_{\sun}$, and the smaller black hole mass of $(7.0ˆ{+4.7}_{-6.4}) \times 10ˆ8$ $M_{\sun}$. The BBH decay time of $(5.1ˆ{+60.5}_{-2.5})\times 10ˆ2$ years provides evidence for the occurrence of black hole mergers. This Letter will demonstrate the interesting possibility of black hole collisions to form a supermassive black hole in the process of evolution, one of the most spectacular natural phenomena in the universe.

#### Nov 12, 2010

1011.2647 (/preprints)
2010-11-12, 09:30