تقرير
On the ridges, undulations & streams in Gaia DR2: Linking the topography of phase-space to the orbital structure of an N-body bar
| العنوان: | On the ridges, undulations & streams in Gaia DR2: Linking the topography of phase-space to the orbital structure of an N-body bar |
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| المؤلفون: | Fragkoudi, F., Katz, D., Trick, W., White, S. D. M., Di Matteo, P., Sormani, M. C., Khoperskov, S., Haywood, M., Hallé, A., Gómez, A. |
| سنة النشر: | 2019 |
| المجموعة: | Astrophysics |
| مصطلحات موضوعية: | Astrophysics - Astrophysics of Galaxies |
| الوصف: | We explore the origin of phase-space substructures revealed by the second Gaia data release in the disc of the Milky Way, such as the ridges in the $V_{\phi}$-$r$ plane, the undulations in the $V_{\phi}$-$r$-$V_r$ space and the streams in the $V_{\phi}$-$V_r$ plane. We use a collisionless N-body simulation with co-spatial thin and thick discs, along with orbit integration, to study the orbital structure close to the Outer Lindblad Resonance (OLR) of the bar. We find that a prominent, long-lived ridge is formed in the $V_{\phi}$-$r$ plane due to the OLR which translates to streams in the $V_{\phi}$-$V_r$ plane and examine which closed periodic and trapped librating orbits are responsible for these features. We find that orbits which carry out small librations around the $x_1(1)$ family are preferentially found at negative $V_r$, giving rise to a `horn'-like feature, while orbits with larger libration amplitudes, trapped around the $x_1(2)$ and $x_1(1)$ families, constitute the positive $V_r$ substructure, i.e. the Hercules-like feature. This changing libration amplitude of orbits will translate to a changing ratio of thin/thick disc stars, which could have implications on the metallicity distribution in this plane. We find that a scenario in which the Sun is placed close to the OLR gives rise to a strong asymmetry in $V_r$ in the $V_{\phi}$-$V_r$ plane (i.e. Hercules vs. `the horn') and subsequently to undulations in the $V_{\phi}$-$r$-$V_r$ space. We also explore a scenario in which the Sun is placed closer to the bar corotation and find that the bar perturbation $alone$ cannot give rise to the these features. Comment: 17 pages, accepted for publication in MNRAS |
| نوع الوثيقة: | Working Paper |
| DOI: | 10.1093/mnras/stz1875 |
| URL الوصول: | http://arxiv.org/abs/1901.07568 |
| رقم الأكسشن: | edsarx.1901.07568 |
| قاعدة البيانات: | arXiv |
| DOI: | 10.1093/mnras/stz1875 |
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