The supermassive black hole in NGC4486a detected with SINFONI at the Very Large Telescope

Abstract

The near-infrared (IR) integral field spectrograph SINFONI at the European Southern Observatory Very Large Telescope opens a new window for the study of central supermassive black holes. With a near-IR spatial resolution similar to Hubble Space Telescope optical and the ability to penetrate dust, it provides the possibility to explore the low-mass end of the relation 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 NGC4486a at a spatial resolution of ~0.1arcsec in the K band. The stellar kinematics were measured with a maximum penalized likelihood method considering the region around the CO absorption band heads. We determined a black hole mass of M_• = (1.25^+0.75_-0.79) × 10⁷M_solar (90 per cent confidence limit) using the Schwarzschild orbit superposition method including the full two-dimensional spatial information. This mass agrees with the predictions of the relation, strengthening its validity at the lower σ end.

Based on observations at the European Southern Observatory (ESO) Very Large Telescope (VLT) (075.B-0236) and on observations made with the Advanced Camera for Surveys onboard the NASA/ESA Hubble Space Telescope (GO Proposals 9401, obtained from the ESO/ST-ECF Science Archive Facility)

E-mail: nnowak@mpe.mpg.de