Triaxial orbit-based modelling of the Milky Way Nuclear Star Cluster

Abstract

We construct triaxial dynamical models for the Milky Way nuclear star cluster using Schwarzschild's orbit superposition technique. We fit the stellar kinematic maps presented in Feldmeier et al. (2014). The models are used to constrain the supermassive black hole mass M_BH, dynamical mass-to-light ratio M/L, and the intrinsic shape of the cluster. Our best-fitting model has M_BH = (3.0 +1.1 -1.3)x10^6 M_sun, M/L = (0.90 +0.76 -0.08) M_sun/L_{sun,4.5micron}, and a compression of the cluster along the line-of-sight. Our results are in agreement with the direct measurement of the supermassive black hole mass using the motion of stars on Keplerian orbits. The mass-to-light ratio is consistent with stellar population studies of other galaxies in the mid-infrared. It is possible that we underestimate M_BH and overestimate the cluster's triaxiality due to observational effects. The spatially semi-resolved kinematic data and extinction within the nuclear star cluster bias the observations to the near side of the cluster, and may appear as a compression of the nuclear star cluster along the line-of-sight. We derive a total dynamical mass for the Milky Way nuclear star cluster of M_MWNSC = (2.1 +-0.7)x10^7 M_sun within a sphere with radius r = 2 x r_eff = 8.4 pc. The best-fitting model is tangentially anisotropic in the central r = 0.5-2 pc of the nuclear star cluster, but close to isotropic at larger radii. Our triaxial models are able to recover complex kinematic substructures in the velocity map.

arXiv comment14 pages, 10 figures. Accepted for publication in MNRAS

References in corpus (37)

• Monitoring stellar orbits around the Massive Black Hole in the Galactic Center
• The Galactic Center Massive Black Hole and Nuclear Star Cluster
• The Proper Motion of Sgr A*: II. The Mass of Sgr A*
• Measuring the inclination and mass-to-light ratio of axisymmetric galaxies via anisotropic Jeans models of stellar kinematics
• Efficient Multi-Gaussian Expansion of galaxies
• Mapping the Three-Dimensional Density of the Galactic Bulge with VVV Red Clump Stars
• Massive Stars in the Quintuplet Cluster
• Dynamical Modeling of Velocity Profiles: The Dark Halo Around the Elliptical Galaxy NGC2434
• Triaxial orbit based galaxy models with an application to the (apparent) decoupled core galaxy NGC 4365
• Two Red Clumps and the X-Shaped Milky Way Bulge
• Reconstructing the stellar mass distributions of galaxies using S4G IRAC 3.6 and 4.5 micron images: II. The conversion from light to mass
• Improved evidence for a black hole in M32 from HST/FOS spectra - II. Axisymmetric dynamical models
• HCN and HCO+ Observations of the Galactic Circumnuclear Disk
• The old nuclear star cluster in the Milky Way: dynamics, mass, statistical parallax, and black hole mass
• Difficulties with Recovering The Masses of Supermassive Black Holes from Stellar Kinematical Data
• Orbital dynamics of three-dimensional bars: I. The backbone of 3D bars. A fiducial case
• A Self-Consistent Dynamical Model for the COBE Detected Galactic Bar
• The Low End of the Supermassive Black Hole Mass Function: Constraining the Mass of a Nuclear Black Hole in NGC 205 via Stellar Kinematics
• The star formation history of the Milky Way's Nuclear Star Cluster
• Really Cool Stars and the Star Formation History at the Galactic Center
• The dynamical M/L-profile and distance of the globular cluster M15
• HST Paschen alpha and 1.9 micron imaging of Sgr A West
• KMOS view of the Galactic Centre - II. Metallicity distribution of late-type stars
• Discovery of low-metallicity stars in the central parsec of the Milky Way
• Discrete dynamical modelling of omega Centauri
• New insights on the formation of nuclear star clusters
• On the rotation of nuclear star clusters formed by cluster-inspirals
• A New Model for the Milky Way Bar
• Recovery of the internal orbital structure of galaxies
• Being WISE I: Validating Stellar Population Models and M/L ratios at 3.4 and 4.6 microns
• Dark matter dynamics in Galactic center
• Constraining the initial mass function of stars in the Galactic Centre
• The benchmark black hole in NGC 4258: dynamical models from high-resolution two-dimensional stellar kinematics
• A Schwarzschild model of the Galactic bar with initial density from N-body simulations
• On the Uncertainties of the Central Density in Axisymmetric Galaxies due to Deprojection
• Dust within the old nuclear star cluster in the Milky Way
• Understanding the central kinematics of globular clusters with simulated integrated-light IFU observations

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