The Supermassive Black Hole at the Heart of Centaurus A: Revealed by Gas- and Stellar Kinematics

TL;DR

This paper reviews recent measurements of the supermassive black hole in Centaurus A using gas and stellar kinematics, highlighting the role of advanced observational techniques like adaptive optics in achieving accurate mass estimates.

Contribution

It provides a comprehensive overview of recent black hole mass measurements in Centaurus A, demonstrating the effectiveness of adaptive optics assisted integral field spectroscopy.

Findings

Black hole mass from gas kinematics: 4.5 (+1.7/-1.0) x 10^7 M_sun

Black hole mass from stellar kinematics: 5.5 +/- 3.0 x 10^7 M_sun

Centaurus A's black hole aligns with the M_BH-sigma relation

Abstract

At less than 4 Mpc distance the radio galaxy NGC 5128 (Centaurus A) is the prime example to study the supermassive black hole and its influence on the environment in great detail. To model and understand the feeding and feedback mechanisms one needs an accurate determination of the mass of the supermassive black hole. The aim of this review is to give an overview of the recent studies that have been dedicated to measure the black hole mass in Centaurus A from both gas and stellar kinematics. It shows how the advancement in observing techniques and instrumentation drive the field of black hole mass measurements and concludes that adaptive optics assisted integral field spectroscopy is the key to identify the effects of the AGN on the surrounding ionised gas. Using data from SINFONI at the ESO Very Large Telescope, the best-fit black hole mass is M_BH=4.5 +1.7/-1.0 x 10^7 Msolar (from H_2 kinematics) and M_BH= (5.5 +/- 3.0) x 10^7 Msolar (from stellar kinematics; both with 3 sigma errors). This is one of the cleanest gas vs star comparison of a M_BH determination, and brings Centaurus A into agreement with the M_BH-sigma relation.