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

Sormani, Mattia C. ; Sanders, Jason L. ; Fritz, Tobias K. ; Smith, Leigh C. ; Gerhard, Ortwin ; Schödel, Rainer ; Magorrian, John ; Neumayer, Nadine ; Nogueras-Lara, Francisco and Feldmeier-Krause, Anja , et al. (2022) In Monthly Notices of the Royal Astronomical Society 512(2). p.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}... (More)

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 $M{\rm NSD} = 10.5{+1.1}{-1.0} \times 108 \, \, \rm M\odot$, 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.

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organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Galaxy: centre, Galaxy: kinematics and dynamics, Galaxy: structure
in
Monthly Notices of the Royal Astronomical Society
volume
512
issue
2
pages
28 pages
publisher
Oxford University Press
external identifiers
  • scopus:85128030913
ISSN
0035-8711
DOI
10.1093/mnras/stac639
language
English
LU publication?
yes
id
01139e01-bd5d-40af-9011-07775591d769
date added to LUP
2022-06-20 16:01:48
date last changed
2025-10-14 09:20:58
@article{01139e01-bd5d-40af-9011-07775591d769,
  abstract     = {{<p>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 $M{\rm NSD} = 10.5{+1.1}{-1.0} \times 108 \, \, \rm M\odot$, 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. </p>}},
  author       = {{Sormani, Mattia C. and Sanders, Jason L. and Fritz, Tobias K. and Smith, Leigh C. and Gerhard, Ortwin and Schödel, Rainer and Magorrian, John and Neumayer, Nadine and Nogueras-Lara, Francisco and Feldmeier-Krause, Anja and Mastrobuono-Battisti, Alessandra and Schultheis, Mathias and Shahzamanian, Banafsheh and Vasiliev, Eugene and Klessen, Ralf S. and Lucas, Philip and Minniti, Dante}},
  issn         = {{0035-8711}},
  keywords     = {{Galaxy: centre; Galaxy: kinematics and dynamics; Galaxy: structure}},
  language     = {{eng}},
  month        = {{05}},
  number       = {{2}},
  pages        = {{1857--1884}},
  publisher    = {{Oxford University Press}},
  series       = {{Monthly Notices of the Royal Astronomical Society}},
  title        = {{Self-consistent modelling of the Milky Way's nuclear stellar disc}},
  url          = {{http://dx.doi.org/10.1093/mnras/stac639}},
  doi          = {{10.1093/mnras/stac639}},
  volume       = {{512}},
  year         = {{2022}},
}