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

TL;DR

This study used the SINFONI instrument at the VLT to measure the supermassive black hole in NGC4486a, confirming the M-sigma relation at low velocity dispersions with high-resolution near-infrared data.

Contribution

First measurement of a supermassive black hole in NGC4486a using near-IR integral field spectroscopy, extending the M-sigma relation to lower velocity dispersions.

Findings

Black hole mass of approximately 1.25 x 10^7 solar masses.

Results support the validity of the M-sigma relation at low sigma.

Demonstrated the effectiveness of SINFONI for black hole studies in dust-obscured regions.

Abstract

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-sigma relation (sigma<120km/s) 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 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_BH=1.25^{+0.75}_{-0.79} x 10^7 M_sun (90% C.L.) using the Schwarzschild orbit superposition method including the full 2-dimensional spatial information. This mass agrees with the predictions of the M-sigma relation, strengthening its validity at the lower sigma end.