Data-driven Dynamics with Orbital Torus Imaging: A Flexible Model of the Vertical Phase Space of the Galaxy
The vertical kinematics of stars near the Sun can be used to measure the total mass distribution near the Galactic disk and to study out-of-equilibrium dynamics. With contemporary stellar surveys, the tracers of vertical dynamics are so numerous and so well measured that the shapes of underlying orb...
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IOP Publishing
2025-01-01
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| Series: | The Astrophysical Journal |
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| Online Access: | https://doi.org/10.3847/1538-4357/ad969a |
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| author | Adrian M. Price-Whelan Jason A. S. Hunt Danny Horta Micah Oeur David W. Hogg Kathryn Johnston Lawrence Widrow |
| author_facet | Adrian M. Price-Whelan Jason A. S. Hunt Danny Horta Micah Oeur David W. Hogg Kathryn Johnston Lawrence Widrow |
| author_sort | Adrian M. Price-Whelan |
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| description | The vertical kinematics of stars near the Sun can be used to measure the total mass distribution near the Galactic disk and to study out-of-equilibrium dynamics. With contemporary stellar surveys, the tracers of vertical dynamics are so numerous and so well measured that the shapes of underlying orbits are almost directly visible in the data through element abundances or even stellar density. These orbits can be used to infer a mass model for the Milky Way, enabling constraints on the dark matter distribution in the inner galaxy. Here, we present a flexible model for foliating the vertical position–velocity phase space with orbits for use in data-driven studies of dynamics. The vertical acceleration profile in the vicinity of the disk, along with the orbital actions, angles, and frequencies for individual stars, can all be derived from that orbit foliation. We show that this framework—“orbital torus imaging” (OTI)—is rigorously justified in the context of dynamical theory, and does a good job of fitting orbits to simulated stellar abundance data with varying degrees of realism. OTI (1) does not require a global model for the Milky Way mass distribution, and (2) does not require detailed modeling of the selection function of the input survey data. We discuss the approximations and limitations of the OTI framework, which currently trades dynamical interpretability for flexibility in representing the data in some regimes, and which also presently separates the vertical and radial dynamics. We release an open-source tool, torusimaging , to accompany this article. |
| format | Article |
| id | doaj-art-bd68df74e93b490cb56c9708b2b16f55 |
| institution | Kabale University |
| issn | 1538-4357 |
| language | English |
| publishDate | 2025-01-01 |
| publisher | IOP Publishing |
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| spelling | doaj-art-bd68df74e93b490cb56c9708b2b16f552025-01-25T04:52:09ZengIOP PublishingThe Astrophysical Journal1538-43572025-01-01979211510.3847/1538-4357/ad969aData-driven Dynamics with Orbital Torus Imaging: A Flexible Model of the Vertical Phase Space of the GalaxyAdrian M. Price-Whelan0https://orcid.org/0000-0003-0872-7098Jason A. S. Hunt1https://orcid.org/0000-0001-8917-1532Danny Horta2https://orcid.org/0000-0003-1856-2151Micah Oeur3https://orcid.org/0000-0001-5636-3108David W. Hogg4https://orcid.org/0000-0003-2866-9403Kathryn Johnston5https://orcid.org/0000-0001-6244-6727Lawrence Widrow6https://orcid.org/0000-0001-6211-8635Center for Computational Astrophysics, Flatiron Institute , 162 Fifth Avenue, New York, NY 10010, USA ; aprice-whelan@flatironinstitute.orgCenter for Computational Astrophysics, Flatiron Institute , 162 Fifth Avenue, New York, NY 10010, USA ; aprice-whelan@flatironinstitute.org; School of Mathematics & Physics, University of Surrey , Guildford, GU2 7XH, UKCenter for Computational Astrophysics, Flatiron Institute , 162 Fifth Avenue, New York, NY 10010, USA ; aprice-whelan@flatironinstitute.orgDepartment of Physics, University of California, Merced , 5200 Lake Road, Merced, CA 95343, USACenter for Computational Astrophysics, Flatiron Institute , 162 Fifth Avenue, New York, NY 10010, USA ; aprice-whelan@flatironinstitute.org; Max-Planck-Institut fur Astronomie , Konigstuhl 17, D-69117 Heidelberg, Germany; Center for Cosmology and Particle Physics, Department of Physics, New York University , 726 Broadway, New York, NY 10003, USADepartment of Astronomy, Columbia University , 550 West 120th Street, New York, NY 10027, USADepartment of Physics, Engineering Physics and Astronomy, Queen’s University , Kingston, K7L 3X5, CanadaThe vertical kinematics of stars near the Sun can be used to measure the total mass distribution near the Galactic disk and to study out-of-equilibrium dynamics. With contemporary stellar surveys, the tracers of vertical dynamics are so numerous and so well measured that the shapes of underlying orbits are almost directly visible in the data through element abundances or even stellar density. These orbits can be used to infer a mass model for the Milky Way, enabling constraints on the dark matter distribution in the inner galaxy. Here, we present a flexible model for foliating the vertical position–velocity phase space with orbits for use in data-driven studies of dynamics. The vertical acceleration profile in the vicinity of the disk, along with the orbital actions, angles, and frequencies for individual stars, can all be derived from that orbit foliation. We show that this framework—“orbital torus imaging” (OTI)—is rigorously justified in the context of dynamical theory, and does a good job of fitting orbits to simulated stellar abundance data with varying degrees of realism. OTI (1) does not require a global model for the Milky Way mass distribution, and (2) does not require detailed modeling of the selection function of the input survey data. We discuss the approximations and limitations of the OTI framework, which currently trades dynamical interpretability for flexibility in representing the data in some regimes, and which also presently separates the vertical and radial dynamics. We release an open-source tool, torusimaging , to accompany this article.https://doi.org/10.3847/1538-4357/ad969aOrbitsCelestial mechanicsGalaxy dynamicsMilky Way dynamicsDark matter densityAstronomical methods |
| spellingShingle | Adrian M. Price-Whelan Jason A. S. Hunt Danny Horta Micah Oeur David W. Hogg Kathryn Johnston Lawrence Widrow Data-driven Dynamics with Orbital Torus Imaging: A Flexible Model of the Vertical Phase Space of the Galaxy The Astrophysical Journal Orbits Celestial mechanics Galaxy dynamics Milky Way dynamics Dark matter density Astronomical methods |
| title | Data-driven Dynamics with Orbital Torus Imaging: A Flexible Model of the Vertical Phase Space of the Galaxy |
| title_full | Data-driven Dynamics with Orbital Torus Imaging: A Flexible Model of the Vertical Phase Space of the Galaxy |
| title_fullStr | Data-driven Dynamics with Orbital Torus Imaging: A Flexible Model of the Vertical Phase Space of the Galaxy |
| title_full_unstemmed | Data-driven Dynamics with Orbital Torus Imaging: A Flexible Model of the Vertical Phase Space of the Galaxy |
| title_short | Data-driven Dynamics with Orbital Torus Imaging: A Flexible Model of the Vertical Phase Space of the Galaxy |
| title_sort | data driven dynamics with orbital torus imaging a flexible model of the vertical phase space of the galaxy |
| topic | Orbits Celestial mechanics Galaxy dynamics Milky Way dynamics Dark matter density Astronomical methods |
| url | https://doi.org/10.3847/1538-4357/ad969a |
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