Supermassive black hole mass in the massive elliptical galaxy M87 from
integral-field stellar dynamics using OASIS and MUSE with adaptive optics:
assessing systematic uncertainties
The massive elliptical galaxy M87 has been the subject of several
supermassive black hole mass measurements from stellar dynamics, gas dynamics,
and recently the black hole shadow by the Event Horizon Telescope (EHT). This
uniquely positions M87 as a benchmark for alternative black hole mass
determination methods. Here we use stellar kinematics extracted from
integral-field spectroscopy observations with Adaptive Optics (AO) using MUSE
and OASIS. We exploit our high-resolution integral field spectroscopy to
spectrally decompose the central AGN from the stars. We derive an accurate
inner stellar-density profile and find it is flatter than previously assumed.
We also use the spectrally-extracted AGN as a reference to accurately determine
the observed MUSE and OASIS AO PSF. We then perform Jeans Anisotropic Modelling
(JAM), with a new flexible spatially-variable anisotropy, and measure the
anisotropy profile, stellar mass-to-light variations, inner dark matter
fraction, and black hole mass. Our preferred black hole mass is MBHβ=(8.7Β±1.2)Γ109Β Mββ. However, using the inner stellar
density from previous studies, we find a preferred black hole mass of MBHβ=(5.5β0.3+0.5β)Γ109Β Mββ, consistent with previous
work. We conduct numerous systematic tests of the kinematics and model
assumptions and conclude that uncertainties in the black hole mass of M87 from
previous determinations may have been underestimated and further analyses are
needed.Comment: 19 pages, 16 figures, 4 tables, Submitted to MNRA