Self-consistent modelling of the Milky Way's nuclear stellar disc. Issue 2 (22nd March 2022)

• Record Type: Journal Article
• 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
• Is Part Of: Monthly notices of the Royal Astronomical Society. Volume 512:Issue 2(2022)
• Page Start: 1857
• Page End: 1884
• Publication Date: 2022-03-22
• Subjects: Galaxy: centre -- Galaxy: kinematics and dynamics -- Galaxy: structure; Astronomy -- Periodicals; Periodicals; 520.5
• DOI: 10.1093/mnras/stac639
• Languages: English
• ISSNs: 0035-8711

Abstract

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 .