# Self-consistent modelling of the Milky Way's nuclear stellar disc

DOI:
10.1093/mnras/stac639
Publication date:
08/05/2022
Main author:
Sormani, Mattia C.
IAA authors:
Schödel, Rainer;Shahzamanian, Banafsheh
Authors:
Sormani, Mattia C.;Sanders, Jason L.;Fritz, Tobias K.;Smith, Leigh C.;Gerhard, Ortwin;Schödel, Rainer;Magorrian, John;Neumayer, Nadine;Nogueras-Lara, Francisco;Feldmeier-Krause, Anja;Mastrobuono-Battisti, Alessandra;Schultheis, Mathias;Shahzamanian, Banafsheh;Vasiliev, Eugene;Klessen, Ralf S.;Lucas, Philip;Minniti, Dante
Journal:
Monthly Notices of the Royal Astronomical Society
Publication type:
Article
Volume:
512
Pages:
1857-1884
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 $30\, {\rm pc}\lesssim R\lesssim 300\, {\rm pc}$. 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 normalized 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 marginalized probability distributions give a total mass of $M_{\rm NSD} = 10.5^{+1.1}_{-1.0} \times 10^8 \, \, \rm M_\odot$, roughly exponential radial and vertical scale lengths of $R_{\rm disc} = 88.6^{+9.2}_{-6.9} \, {\rm pc}$ and $H_{\rm disc}=28.4^{+5.5}_{-5.5} \, {\rm pc}$, respectively, and a velocity dispersion $\sigma \simeq 70\, {\rm km\, s^{-1}}$ 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.
Database: