Self-consistent modelling of the Milky Way's Nuclear Stellar Disc
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| Main Authors: | , , , , , , , , , , , , , , , , |
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| Format: | Preprint |
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2021
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| _version_ | 1866908937441247232 |
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| author | Sormani, Mattia C. Sanders, Jason L. Fritz, Tobias K. Smith, Leigh C. Gerhard, Ortwin Schoedel, 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 |
| author_facet | Sormani, Mattia C. Sanders, Jason L. Fritz, Tobias K. Smith, Leigh C. Gerhard, Ortwin Schoedel, 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 |
| contents | 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 $M_{\rm NSD} = 10.5^{+1.1}_{-1.0} \times10^8 \,{\rm M_\odot}$, roughly exponential radial and vertical scale-lengths of $R_{\rm disc} = 88.6^{+9.2}_{-6.9}$ pc and $H_{\rm disc}=28.4^{+5.5}_{-5.5}$ pc respectively, and a velocity dispersion $σ\simeq 70$ 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. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2111_12713 |
| institution | arXiv |
| publishDate | 2021 |
| record_format | arxiv |
| spellingShingle | 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 Schoedel, 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 Astrophysics of Galaxies 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 $M_{\rm NSD} = 10.5^{+1.1}_{-1.0} \times10^8 \,{\rm M_\odot}$, roughly exponential radial and vertical scale-lengths of $R_{\rm disc} = 88.6^{+9.2}_{-6.9}$ pc and $H_{\rm disc}=28.4^{+5.5}_{-5.5}$ pc respectively, and a velocity dispersion $σ\simeq 70$ 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. |
| title | Self-consistent modelling of the Milky Way's Nuclear Stellar Disc |
| topic | Astrophysics of Galaxies |
| url | https://arxiv.org/abs/2111.12713 |