Testing the robustness of black hole mass measurements with ALMA and
  MUSE
  We present our ongoing work of using two independent tracers to estimate the
supermassive black hole mass in the nearby early-type galaxy NGC 6958; namely
integrated stellar and molecular gas kinematics. We used data from the Atacama
Large Millimeter/submillimeter Array (ALMA), and the adaptive-optics assisted
Multi-Unit Spectroscopic Explorer (MUSE) and constructed state-of-the-art
dynamical models. The different methods provide black hole masses of $(2.89\pm
2.05) \times 10^8M_{\odot}$ from stellar kinematics and $(1.35\pm 0.09) \times
10^8M_{\odot}$ from molecular gas kinematics which are consistent within their
$3\sigma$ uncertainties. Compared to recent M$_{\rm BH}$ - $\sigma_{\rm e}$
scaling relations, we derive a slightly over-massive black hole. Our results
also confirm previous findings that gas-based methods tend to provide lower
black hole masses than stellar-based methods. More black hole mass measurements
and an extensive analysis of the method-dependent systematics are needed in the
future to understand this noticeable discrepancy.
