Exploring Asymmetric Substructures of the Outer Disk Based on the Conjugate Angle of the Radial Action
We use the conjugate angle of radial action ( θ _R ), the best representation of the orbital phase, to explore the “midplane,” “north branch,” “south branch,” and “Monoceros area” disk structures that were previously revealed in the LAMOST K giants. The former three substructures, identified by thei...
| Main Authors: | , , , , , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
IOP Publishing
2023-01-01
|
| Series: | The Astrophysical Journal |
| Subjects: | |
| Online Access: | https://doi.org/10.3847/1538-4357/acefc0 |
| _version_ | 1797667013131239424 |
|---|---|
| author | Y. Xu C. Liu Z. Li H. Tian Sarah A. Bird H. J. Newberg S. Shao L. C. Deng |
| author_facet | Y. Xu C. Liu Z. Li H. Tian Sarah A. Bird H. J. Newberg S. Shao L. C. Deng |
| author_sort | Y. Xu |
| collection | DOAJ |
| description | We use the conjugate angle of radial action ( θ _R ), the best representation of the orbital phase, to explore the “midplane,” “north branch,” “south branch,” and “Monoceros area” disk structures that were previously revealed in the LAMOST K giants. The former three substructures, identified by their 3D kinematical distributions, have been shown to be projections of the phase space spiral (resulting from nonequilibrium phase mixing). In this work, we find that all of these substructures associated with the phase spiral show high aggregation in conjugate angle phase space, indicating that the clumping in conjugate angle space is a feature of ongoing, incomplete phase mixing. We do not find the Z – V _Z phase spiral located in the “Monoceros area,” but we do find a very highly concentrated substructure in the quadrant of conjugate angle space with the orbital phase from the apocenter to the guiding radius. The existence of the clump in conjugate angle space provides a complementary way to connect the “Monoceros area” with the direct response to a perturbation from a significant gravitationally interactive event. Using test particle simulations, we show that these features are analogous to disturbances caused by the impact of the last passage of the Sagittarius dwarf spheroidal galaxy. |
| first_indexed | 2024-03-11T20:07:00Z |
| format | Article |
| id | doaj.art-f0a5020ac6944c789caf9ee17c42e7e7 |
| institution | Directory Open Access Journal |
| issn | 1538-4357 |
| language | English |
| last_indexed | 2024-03-11T20:07:00Z |
| publishDate | 2023-01-01 |
| publisher | IOP Publishing |
| record_format | Article |
| series | The Astrophysical Journal |
| spelling | doaj.art-f0a5020ac6944c789caf9ee17c42e7e72023-10-03T15:47:37ZengIOP PublishingThe Astrophysical Journal1538-43572023-01-0195611310.3847/1538-4357/acefc0Exploring Asymmetric Substructures of the Outer Disk Based on the Conjugate Angle of the Radial ActionY. Xu0https://orcid.org/0000-0002-2459-3483C. Liu1https://orcid.org/0000-0002-1802-6917Z. Li2https://orcid.org/0000-0001-5017-7021H. Tian3https://orcid.org/0000-0003-3347-7596Sarah A. Bird4https://orcid.org/0000-0002-5469-5149H. J. Newberg5https://orcid.org/0000-0001-8348-0983S. Shao6https://orcid.org/0000-0001-8382-6323L. C. Deng7https://orcid.org/0000-0001-9073-9914CAS Key Laboratory of Optical Astronomy, National Astronomical Observatories, Chinese Academy of Sciences, Beijing, 100101, People’s Republic of China ; xuyan@nao.cas.cnKey Laboratory of Space Astronomy and Technology, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100101, People’s Republic of ChinaDepartment of Astronomy, School of Physics and Astronomy, Shanghai Jiao Tong University , 800 Dongchuan Road, Shanghai 200240, People’s Republic of China; Key Laboratory for Particle Astrophysics and Cosmology (MOE)/Shanghai Key Laboratory for Particle Physics and Cosmology, Shanghai 200240, People’s Republic of ChinaKey Laboratory of Space Astronomy and Technology, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100101, People’s Republic of ChinaCollege of Science, China Three Gorges University , Yichang 443002, People’s Republic of China; Center for Astronomy and Space Sciences, China Three Gorges University , Yichang 443002, People’s Republic of ChinaDepartment of Physics, Applied Physics and Astronomy, Rensselaer Polytechnic Institute , Troy, NY 12180, USAKey Laboratory for Computational Astrophysics, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100101, People’s Republic of ChinaCAS Key Laboratory of Optical Astronomy, National Astronomical Observatories, Chinese Academy of Sciences, Beijing, 100101, People’s Republic of China ; xuyan@nao.cas.cnWe use the conjugate angle of radial action ( θ _R ), the best representation of the orbital phase, to explore the “midplane,” “north branch,” “south branch,” and “Monoceros area” disk structures that were previously revealed in the LAMOST K giants. The former three substructures, identified by their 3D kinematical distributions, have been shown to be projections of the phase space spiral (resulting from nonequilibrium phase mixing). In this work, we find that all of these substructures associated with the phase spiral show high aggregation in conjugate angle phase space, indicating that the clumping in conjugate angle space is a feature of ongoing, incomplete phase mixing. We do not find the Z – V _Z phase spiral located in the “Monoceros area,” but we do find a very highly concentrated substructure in the quadrant of conjugate angle space with the orbital phase from the apocenter to the guiding radius. The existence of the clump in conjugate angle space provides a complementary way to connect the “Monoceros area” with the direct response to a perturbation from a significant gravitationally interactive event. Using test particle simulations, we show that these features are analogous to disturbances caused by the impact of the last passage of the Sagittarius dwarf spheroidal galaxy.https://doi.org/10.3847/1538-4357/acefc0Galaxy kinematicsGalaxy anticenters |
| spellingShingle | Y. Xu C. Liu Z. Li H. Tian Sarah A. Bird H. J. Newberg S. Shao L. C. Deng Exploring Asymmetric Substructures of the Outer Disk Based on the Conjugate Angle of the Radial Action The Astrophysical Journal Galaxy kinematics Galaxy anticenters |
| title | Exploring Asymmetric Substructures of the Outer Disk Based on the Conjugate Angle of the Radial Action |
| title_full | Exploring Asymmetric Substructures of the Outer Disk Based on the Conjugate Angle of the Radial Action |
| title_fullStr | Exploring Asymmetric Substructures of the Outer Disk Based on the Conjugate Angle of the Radial Action |
| title_full_unstemmed | Exploring Asymmetric Substructures of the Outer Disk Based on the Conjugate Angle of the Radial Action |
| title_short | Exploring Asymmetric Substructures of the Outer Disk Based on the Conjugate Angle of the Radial Action |
| title_sort | exploring asymmetric substructures of the outer disk based on the conjugate angle of the radial action |
| topic | Galaxy kinematics Galaxy anticenters |
| url | https://doi.org/10.3847/1538-4357/acefc0 |
| work_keys_str_mv | AT yxu exploringasymmetricsubstructuresoftheouterdiskbasedontheconjugateangleoftheradialaction AT cliu exploringasymmetricsubstructuresoftheouterdiskbasedontheconjugateangleoftheradialaction AT zli exploringasymmetricsubstructuresoftheouterdiskbasedontheconjugateangleoftheradialaction AT htian exploringasymmetricsubstructuresoftheouterdiskbasedontheconjugateangleoftheradialaction AT sarahabird exploringasymmetricsubstructuresoftheouterdiskbasedontheconjugateangleoftheradialaction AT hjnewberg exploringasymmetricsubstructuresoftheouterdiskbasedontheconjugateangleoftheradialaction AT sshao exploringasymmetricsubstructuresoftheouterdiskbasedontheconjugateangleoftheradialaction AT lcdeng exploringasymmetricsubstructuresoftheouterdiskbasedontheconjugateangleoftheradialaction |