NGC 3115 is an S0 galaxy that has always been considered to have a pure absorption-line spectrum .
Some recent studies have detected a compact radio-emitting nucleus in this object , coinciding with the photometric center and with a candidate for the X-ray nucleus .
This is evidence of the existence of a low-luminosity active galactic nucleus ( AGN ) in the galaxy , although no emission line has ever been observed .
We report the detection of an emission-line spectrum of a type 1 AGN in NGC 3115 , with an H \alpha luminosity of L _ { H \alpha } = ( 4.2 \pm 0.4 ) \times 10 ^ { 37 } erg s ^ { -1 } .
Our analysis revealed that this AGN is located at a projected distance of \sim 0 \arcsec .29 \pm 0 \arcsec .05 ( corresponding to \sim 14.3 \pm 2.5 pc ) from the stellar bulge center , which is coincident with the kinematic center of this object ’ s stellar velocity map .
The black hole corresponding to the observed off-centered AGN may form a binary system with a black hole located at the stellar bulge center .
However , it is also possible that the displaced black hole is the merged remnant of the binary system coalescence , after the “ kick ” caused by the asymmetric emission of gravitational waves .
We propose that certain features in the stellar velocity dispersion map are the result of perturbations caused by the off-centered AGN .