AN OFF-CENTERED ACTIVE GALACTIC NUCLEUS IN NGC 3115

• Published in: Astrophysical journal. Letters Vol. 796; no. 1; pp. 1 - 6
• Main Authors: Menezes, R B, Steiner, J E, Ricci, T V
• Format: Journal Article
• Language: English
• Published: United States 20.11.2014
• Subjects: ABSORPTION SPECTRA; Active galactic nuclei; ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ASYMMETRY; BINARY STARS; Binary systems; BLACK HOLES; COALESCENCE; Coalescing; DETECTION; Dispersions; DISTURBANCES; Emission; GALAXIES; GALAXY NUCLEI; LUMINOSITY; Nuclei; PHOTOMETRY; STAR CLUSTERS; VELOCITY; X RADIATION
• ISSN: 2041-8213; 2041-8205; 2041-8213
• DOI: 10.1088/2041-8205/796/1/L13

NGC 3115 is an SO 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 sub(H alpha ) = (4.2 + or - 0.4) x 10 super(37) erg s super(-1). Our analysis revealed that this AGN is located at a projected distance of ~0."29 + or - 0."05 (corresponding to ~ 14.3 + or - 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.