An Upper Limit on the Mass of a Central Black Hole in the Large Magellanic Cloud from the Stellar Rotation Field

TL;DR

This study uses high-resolution spectroscopic data from MUSE to place an upper limit on the mass of a potential central black hole in the Large Magellanic Cloud, informing theories of black hole growth in low-mass galaxies.

Contribution

It provides the first high-resolution velocity map of the LMC's center and establishes a new upper limit on a central black hole's mass using integral-field spectroscopy.

Findings

Upper limit of 10^7.1 solar masses for a central black hole

Velocity gradient detected at 1 arcmin^2 resolution

Results consistent with known black hole scaling relations

Abstract

We constrain the possible presence of a central black hole (BH) in the center of the Large Magellanic Cloud (LMC). This requires spectroscopic measurements over an area of order a square degree, due to the poorly known position of the kinematic center. Such measurements are now possible with the impressive field of view of the Multi Unit Spectroscopic Explorer (MUSE) on the ESO Very Large Telescope. We used the Calcium Triplet (~850nm) spectral lines in many short-exposure MUSE pointings to create a two-dimensional integrated-light line-of-sight velocity map from the ~$10^8$ individual spectra, taking care to identify and remove Galactic foreground populations. The data reveal a clear velocity gradient at an unprecedented spatial resolution of 1 arcmin$^{2}$. We fit kinematic models to arrive at a $3\sigma$ upper-mass-limit of $10^{7.1}$ M$_{Sun}$ for any central BH - consistent with the known scaling relations for supermassive black holes and their host systems. This adds to the growing body of knowledge on the presence of BHs in low-mass and dwarf galaxies, and their scaling relations with host-galaxy properties, which can shed light on theories of BH growth and host system interaction.