Dynamical mass distribution and velocity structure of the Galactic centre
arXiv:2506.06014 · doi:10.1051/0004-6361/202554630
Abstract
The inner ~200 pc region of the Milky Way contains a nuclear stellar disc and a nuclear star cluster that are embedded in the larger Galactic bar. These stellar systems overlap spatially, which makes it challenging to separate stars that belong to the nuclear stellar systems, to deduce their internal dynamics, and to derive the central Galactic potential. Discrete stellar kinematics probe the mass distribution of a stellar system, and chemical tracers such as stellar metallicity can further separate multiple stellar populations that can have distinct kinematic properties. We took advantage of the information provided by discrete stellar kinematics and the metallicity in the Galactic centre using discrete chemo-dynamical modelling. We fitted axisymmetric Jeans models to discrete data of 4,600 stars. We fitted the stars as either one population plus a background component or as two populations plus a background that represents the bar. We tested the robustness of the inferred gravitational potential against a varying mass of the supermassive black hole, including dark matter, or a radially varying mass-to-light ratio. We obtained robust results on the fit with a single population and a background component. We obtained a supermassive black hole mass of (4.35 M, and we find that a dark matter component and radial variation in the mass-to-light ratio are negligible. We derived the enclosed mass profile of the inner ~60 pc and found a lower mass than reported in the literature in the region of ~5-30 pc. In our two-population fit, we found a high-[M/H] population that contributes more than 90% to the total stellar density. The properties of the high-[M/H] population are consistent with in situ formation after gas inflow from the Galactic disc via the bar. The distinct kinematic properties of the low-[M/H] population indicate a different origin. [abridged]
15 pages (+ 5 pages Appendix), 10 (+ 5) figures, accepted A&A
References in corpus (39)
- SciPy 1.0--Fundamental Algorithms for Scientific Computing in Python
- Array Programming with NumPy
- The Astropy Project: Sustaining and Growing a Community-oriented Open-source Project and the Latest Major Release (v5.0) of the Core Package
- The Two Young Star Disks in the Central Parsec of the Galaxy: Properties, Dynamics and Formation
- Measuring the inclination and mass-to-light ratio of axisymmetric galaxies via anisotropic Jeans models of stellar kinematics
- Dynamical modelling of the Galactic bulge and bar: the Milky Way's bar pattern speed, stellar, and dark matter mass distribution
- An Improved Distance and Mass Estimate for Sgr A* from a Multistar Orbit Analysis
- The mass distribution in the Galactic Centre from interferometric astrometry of multiple stellar orbits
- The old nuclear star cluster in the Milky Way: dynamics, mass, statistical parallax, and black hole mass
- Large scale kinematics and dynamical modelling of the Milky Way nuclear star cluster
- The Proper Motion of Sagittarius A*: III. The Case for a Supermassive Black Hole
- Kinematics of the old stellar population at the Galactic Center
- Kinematic signatures of nuclear discs and bar-driven secular evolution in nearby galaxies of the MUSE TIMER project
- The formation of stellar nuclear discs in bar-induced gas inflows
- KMOS view of the Galactic Centre - II. Metallicity distribution of late-type stars
- GALACTICNUCLEUS: A high-angular-resolution JHKs imaging survey of the Galactic centre II. First data release of the catalogue and the most detailed CMDs of the GC
- On the rotation of nuclear star clusters formed by cluster-inspirals
- New constraints on the structure of the nuclear stellar cluster of the Milky Way from star counts and MIR imaging
- The young stars in the Galactic Center
- A discrete chemo-dynamical model of the dwarf spheroidal galaxy Sculptor: mass profile, velocity anisotropy and internal rotation
- The Milky Way's nuclear stellar disc: A dynamically cool and metal-rich component formed from the Central Molecular Zone?
- Being WISE I: Validating Stellar Population Models and M/L ratios at 3.4 and 4.6 microns
- Jeans modelling of the Milky Way's nuclear stellar disc
- Disentangling the formation history of galaxies via population-orbit superposition: method validation
- Asymmetric spatial distribution of sub-solar metallicity stars in the Milky Way nuclear star cluster
- On the origin of a rotating metal-poor stellar population in the Milky Way Nuclear Cluster
- A discrete chemo-dynamical model of the giant elliptical galaxy NGC 5846: dark matter fraction, internal rotation and velocity anisotropy out to six effective radii
- Revealing the Formation of the Milky Way Nuclear Star Cluster via Chemo-Dynamical Modeling
- Galaxy And Mass Assembly (GAMA): The Consistency of GAMA and WISE Derived Mass-to-Light Ratios
- 2D kinematics of massive stars near the Galactic Center
- A KMOS survey of the nuclear disk of the Milky Way I: Survey design and metallicities
- VIRAC2: NIR Astrometry and Time Series Photometry for 500M+ Stars from the VVV and VVVX Surveys
- Constraining the population of isolated massive stars within the Central Molecular Zone
- The peculiar kinematics of the multiple populations in the globular cluster Messier 80 (NGC 6093)
- Measuring the Orbits of the Arches and Quintuplet Clusters using HST and Gaia: Exploring Scenarios for Star Formation Near the Galactic Center
- A Deep View into the Nucleus of the Sagittarius Dwarf Spheroidal Galaxy with MUSE. III. Discrete multi-component population-dynamical models based on the Jeans equations
- The absolute proper motions of the Arches and Quintuplet clusters
- Milky Way globular clusters on cosmological timescales. II. Interaction with the Galactic centre
- A spectroscopic map of the Galactic centre -- Observations and resolved stars