VLT Kinematics for omega Centauri: Further Support for a Central Black Hole

TL;DR

This study uses VLT-FLAMES data to analyze the kinematics of omega Centauri, providing evidence supporting the presence of a central intermediate-mass black hole with a mass around 47,000 solar masses.

Contribution

It offers new integrated spectra and dynamical modeling that reinforce previous indications of a central black hole in omega Centauri.

Findings

Radial velocity dispersion rises to 22.8 km/s in the center.

Black hole mass estimated at approximately 47,000 solar masses.

Discrepancies with proper motion data set results.

Abstract

The Galactic globular cluster omega Centauri is a prime candidate for hosting an intermediate mass black hole. Recent measurements lead to contradictory conclusions on this issue. We use VLT-FLAMES to obtain new integrated spectra for the central region of omega Centauri. We combine these data with existing measurements of the radial velocity dispersion profile taking into account a new derived center from kinematics and two different centers from the literature. The data support previous measurements performed for a smaller field of view and show a discrepancy with the results from a large proper motion data set. We see a rise in the radial velocity dispersion in the central region to 22.8+-1.2 km/s, which provides a strong sign for a central black hole. Isotropic dynamical models for omega Centauri imply black hole masses ranging from 3.0 to 5.2x10^4 solar masses depending on the center. The best-fitted mass is 4.7+-1.0x10^4 solar masses.