The supermassive black hole in NGC4486a detected with SINFONI at the VLT†

The near-infrared integral field spectrograph SINFONI at the ESO VLT opens a new window for the study of central supermassive black holes. With a near-IR spatial resolution similar to HST optical and the ability to penetrate dust it provides the possibility to explore the low-mass end of the M•-σ relation (σ < 120 km s−1) where so far very few black hole masses were measured with stellar dynamics. With SINFONI we observed the central region of the low-luminosity elliptical galaxy NGC 4486a at a spatial resolution of ≈ 0.1′′ in the K band. The stellar kinematics was measured with a maximum penalised likelihood method considering the region around the CO absorption band heads. We determined a black hole mass of M• = (1.25 −0.79)×10 M (90 % C.L.) using the Schwarzschild orbit superposition method including the full 2dimensional spatial information. This mass agrees with the predictions of the M•-σ relation, strengthening its validity at the lower σ end.