Self-consistent modelling of the Milky Way's Nuclear Stellar Disc

Abstract

The Nuclear Stellar Disc (NSD) is a flattened high-density stellar structure that dominates the gravitational field of the Milky Way at Galactocentric radius $30\lesssim R\lesssim 300$ pc. We construct axisymmetric self-consistent equilibrium dynamical models of the NSD in which the distribution function is an analytic function of the action variables. We fit the models to the normalised kinematic distributions (line-of-sight velocities + VIRAC2 proper motions) of stars in the NSD survey of Fritz et al., taking the foreground contamination due to the Galactic Bar explicitly into account using an $N$-body model. The posterior marginalised probability distributions give a total mass of $M_{\mathrm{NSD}}=10.5_{-1.0}^{+1.1}\times 10^8{\mathrm{M}}_{\odot }$, roughly exponential radial and vertical scale-lengths of $R_{\mathrm{disc}}=88.6_{-6.9}^{+9.2}$ pc and $H_{\mathrm{disc}}=28.4_{-5.5}^{+5.5}$ pc respectively, and a velocity dispersion $\sigma \simeq 70$ km/s that decreases with radius. We find that the assumption that the NSD is axisymmetric provides a good representation of the data. We quantify contamination from the Galactic Bar in the sample, which is substantial in most observed fields. Our models provide the full 6D (position+velocity) distribution function of the NSD, which can be used to generate predictions for future surveys. We make the models publicly available as part of the software package AGAMA.

Accepted for publication in MNRAS. Corrected figures 9,A2,A3,A4

References in corpus (101)

• emcee: The MCMC Hammer
• On the variation of the Initial Mass Function
• PARSEC: stellar tracks and isochrones with the PAdova and TRieste Stellar Evolution Code
• The Galaxy in Context: Structural, Kinematic and Integrated Properties
• A new generation of PARSEC-COLIBRI stellar isochrones including the TP-AGB phase
• VISTA Variables in the Via Lactea (VVV): The public ESO near-IR variability survey of the Milky Way
• A geometric distance measurement to the Galactic Center black hole with 0.3% uncertainty
• The Proper Motion of Sgr A*: II. The Mass of Sgr A*
• Constraints from Dynamical Friction on the Dark Matter Content of Barred Galaxies
• AGAMA: Action-based galaxy modelling architecture
• Measuring the inclination and mass-to-light ratio of axisymmetric galaxies via anisotropic Jeans models of stellar kinematics
• The Nuclear Bulge of the Galaxy. III. Large-Scale Physical Characteristics of Stars and Interstellar Matter
• Mapping the Three-Dimensional Density of the Galactic Bulge with VVV Red Clump Stars
• Dynamical modelling of the Galactic bulge and bar: the Milky Way's bar pattern speed, stellar, and dark matter mass distribution
• The Structure of the Milky Way's Bar Outside the Bulge
• A 100-parsec elliptical and twisted ring of cold and dense molecular clouds revealed by Herschel around the Galactic Center
• What controls star formation in the central 500 pc of the Galaxy?
• The nuclear star cluster of the Milky Way: proper motions and mass
• Actions for axisymmetric potentials
• Gaia DR2 Proper Motions of Dwarf Galaxies within 420 kpc: Orbits, Milky Way Mass, Tidal Influences, Planar Alignments, and Group Infall
• Interstellar Extinction Law in the J, H, and Ks Bands toward the Galactic Center
• Evolutionary synthesis of stellar populations: a modular tool
• Molecular gas kinematics within the central 250 pc of the Milky Way
• Gas Dynamics in the Milky Way: Second Pattern Speed and Large-Scale Morphology
• AINUR: Atlas of Images of NUclear Rings
• Surface Brightness Profile of the Milky Way's Nuclear Star Cluster
• The old nuclear star cluster in the Milky Way: dynamics, mass, statistical parallax, and black hole mass
• Made-to-measure N-body systems
• Star formation rates and efficiencies in the Galactic Centre
• Distribution functions for the Milky Way
• An Extended Star Formation History for the Galactic Center from Hubble Space Telescope/NICMOS Observations
• Gas flow models in the Milky Way embedded bars
• VIRAC: The VVV Infrared Astrometric Catalogue
• Large scale kinematics and dynamical modelling of the Milky Way nuclear star cluster
• Models of our Galaxy II
• NMAGIC: Fast Parallel Implementation of a Chi-Squared-Made-to-Measure Algorithm for Modelling Observational Data
• Kinematics of the old stellar population at the Galactic Center
• Time Inference with MUSE in Extragalactic Rings (TIMER): Properties of the Survey and High-Level Data Products
• Stellar density profile and mass of the Milky Way Bulge from VVV data
• Early formation and recent starburst activity in the nuclear disc of the Milky Way
• Gas flow in barred potentials - III. Effects of varying the Quadrupole
• A review of action estimation methods for galactic dynamics
• A Dynamical Model for Gas Flows, Star Formation, and Nuclear Winds in Galactic Centres
• A Distinct Structure Inside the Galactic Bar
• Simulations of the Milky Way's central molecular zone -- I. Gas dynamics
• The Mass Inflow Rate in the Barred Galaxy NGC 1530
• Resonance sweeping by a decelerating Galactic bar
• 'The Brick' is not a brick: A comprehensive study of the structure and dynamics of the Central Molecular Zone cloud G0.253+0.016
• Kinematic signatures of nuclear discs and bar-driven secular evolution in nearby galaxies of the MUSE TIMER project
• The multiphase gas structure and kinematics in the circumnuclear region of NGC 5728
• Mapping the Milky Way bulge at high resolution: the 3D dust extinction, CO, and X factor maps
• Extended distribution functions for our Galaxy
• Simulations of the Milky Way's central molecular zone -- II. Star formation
• Extinction ratios in the inner Galaxy as revealed by the VVV survey
• Mass inflow rate into the Central Molecular Zone: observational determination and evidence of episodic accretion
• Tree-ring structure of Galactic bar resonance
• A theoretical explanation for the Central Molecular Zone asymmetry
• The Life Cycle of the Central Molecular Zone. I: Inflow, Star Formation, and Winds
• The inside-out formation of nuclear discs and the absence of old central spheroids in barred galaxies of the TIMER survey
• The inner Galactic bar traced by the VVV survey
• Effects of Gas on Formation and Evolution of Stellar Bars and Nuclear Rings in Disk Galaxies
• Triaxial orbit-based modelling of the Milky Way Nuclear Star Cluster
• Another bar in the Bulge
• Gas dynamics in the Milky Way: a low pattern speed model
• Star formation history of the Galactic bulge from deep HST imaging of low reddening windows
• The inner Galactic bulge: evidence for a nuclear bar?
• New constraints on the structure of the nuclear stellar cluster of the Milky Way from star counts and MIR imaging
• Gas Dynamics in the Galaxy: Total Mass Distribution and the Bar Pattern Speed
• Magnetically Confined Interstellar Hot Plasma in the Nuclear Bulge of our Galaxy
• Trapped orbits and solar-neighbourhood kinematics
• Nuclear Stellar Disks in Spiral Galaxies
• Self-consistent flattened isochrone models
• Age Dating the Galactic Bar with the Nuclear Stellar Disc
• Kinematic Detection of the Galactic Nuclear Disc
• The Milky Way's nuclear stellar disc: A dynamically cool and metal-rich component formed from the Central Molecular Zone?
• The inner two degrees of the Milky Way. Evidence of a chemical difference between the Galactic Center and the surrounding inner bulge stellar populations
• Origin of the high v_los feature in the Galactic bar
• Transverse kinematics of the Galactic bar-bulge from VVV and Gaia
• Discovery of RR Lyrae Stars in the Nuclear Bulge of the Milky Way
• Jeans modelling of the Milky Way's nuclear stellar disc
• Massive Clusters in the Inner Regions of NGC 1365: Cluster Formation and Gas Dynamics in Galactic Bars
• H2O Southern Galactic Plane Survey (HOPS): Paper III - Properties of Dense Molecular Gas across the Inner Milky Way
• The distribution of maser stars in the inner Milky Way: the effect of a weak, rotating bar
• CO Distribution and Kinematics Along the Bar in the Strongly Barred Spiral NGC 7479
• Clocking the assembly of double-barred galaxies with the MUSE TIMER project
• The VVV Survey RR Lyrae Population in the Galactic Centre Region
• Kinematics of classical Cepheids in the Nuclear Stellar Disk
• GALACTICNUCLEUS: A high-angular-resolution $JH{K}_s$ imaging survey of the Galactic centre. IV. Extinction maps and de-reddened photometry
• A Kiloparsec-Scale Nuclear Stellar Disk in the Milky Way as a Possible Explanation of the High Velocity Peaks in the Galactic Bulge
• The nuclear star cluster and nuclear stellar disc of the Milky Way: Different stellar population and star formation history
• A KMOS survey of the nuclear disk of the Milky Way I: Survey design and metallicities
• Resonant Orbits and the High Velocity Peaks Towards the Bulge
• Star Formation in Nuclear Rings with the TIGRESS Framework
• Dust within the old nuclear star cluster in the Milky Way
• Distance to three molecular clouds in the central molecular zone
• Effects of Varying Mass Inflows on Star Formation in Nuclear Rings of Barred Galaxies
• Galaxies within galaxies in the TIMER survey: stellar populations of inner bars are scaled replicas of main bars
• Predicted Stellar Kinematics of a Kiloparsec-Scale Nuclear Disc (or Ring) in the Milky Way
• A new distance to the Brick, the dense molecular cloud G0.253+0.016
• Understanding the velocity distribution of the Galactic Bulge with APOGEE and Gaia
• The Pattern Speed of the Milky Way Bar/Bulge from VIRAC & Gaia