Stream-orbit misalignment I: The dangers of orbit-fitting
Tidal streams don't, in general, delineate orbits. A stream-orbit misalignment is expected to lead to biases when using orbit-fitting to constrain models for the Galactic potential. In this first of two papers we discuss the expected magnitude of the misalignment and the resulting dangers of us...
| Main Authors: | , |
|---|---|
| Format: | Journal article |
| Izdano: |
2013
|
| _version_ | 1826304337468456960 |
|---|---|
| author | Sanders, J Binney, J |
| author_facet | Sanders, J Binney, J |
| author_sort | Sanders, J |
| collection | OXFORD |
| description | Tidal streams don't, in general, delineate orbits. A stream-orbit misalignment is expected to lead to biases when using orbit-fitting to constrain models for the Galactic potential. In this first of two papers we discuss the expected magnitude of the misalignment and the resulting dangers of using orbit-fitting algorithms to constrain the potential. We summarize data for known streams which should prove useful for constraining the Galactic potential, and compute their actions in a realistic Galactic potential. We go on to discuss the formation of tidal streams in angle-action space, and explain why, in general, streams do not delineate orbits. The magnitude of the stream-orbit misalignment is quantified for a logarithmic potential and a multi-component Galactic potential. Specifically, we focus on the expected misalignment for the known streams. By introducing a two-parameter family of realistic Galactic potentials we demonstrate that assuming these streams delineate orbits can lead to order one errors in the halo flattening and halo-to-disc force ratio at the Sun. We present a discussion of the dependence of these results on the progenitor mass, and demonstrate that the misalignment is mass-independent for the range of masses of observed streams. Hence, orbit-fitting does not yield better constraints on the potential if one uses narrower, lower-mass streams. |
| first_indexed | 2024-03-07T06:16:17Z |
| format | Journal article |
| id | oxford-uuid:f12f3830-8184-4de1-8f37-c892842fe98e |
| institution | University of Oxford |
| last_indexed | 2024-03-07T06:16:17Z |
| publishDate | 2013 |
| record_format | dspace |
| spelling | oxford-uuid:f12f3830-8184-4de1-8f37-c892842fe98e2022-03-27T11:54:07ZStream-orbit misalignment I: The dangers of orbit-fittingJournal articlehttp://purl.org/coar/resource_type/c_dcae04bcuuid:f12f3830-8184-4de1-8f37-c892842fe98eSymplectic Elements at Oxford2013Sanders, JBinney, JTidal streams don't, in general, delineate orbits. A stream-orbit misalignment is expected to lead to biases when using orbit-fitting to constrain models for the Galactic potential. In this first of two papers we discuss the expected magnitude of the misalignment and the resulting dangers of using orbit-fitting algorithms to constrain the potential. We summarize data for known streams which should prove useful for constraining the Galactic potential, and compute their actions in a realistic Galactic potential. We go on to discuss the formation of tidal streams in angle-action space, and explain why, in general, streams do not delineate orbits. The magnitude of the stream-orbit misalignment is quantified for a logarithmic potential and a multi-component Galactic potential. Specifically, we focus on the expected misalignment for the known streams. By introducing a two-parameter family of realistic Galactic potentials we demonstrate that assuming these streams delineate orbits can lead to order one errors in the halo flattening and halo-to-disc force ratio at the Sun. We present a discussion of the dependence of these results on the progenitor mass, and demonstrate that the misalignment is mass-independent for the range of masses of observed streams. Hence, orbit-fitting does not yield better constraints on the potential if one uses narrower, lower-mass streams. |
| spellingShingle | Sanders, J Binney, J Stream-orbit misalignment I: The dangers of orbit-fitting |
| title | Stream-orbit misalignment I: The dangers of orbit-fitting |
| title_full | Stream-orbit misalignment I: The dangers of orbit-fitting |
| title_fullStr | Stream-orbit misalignment I: The dangers of orbit-fitting |
| title_full_unstemmed | Stream-orbit misalignment I: The dangers of orbit-fitting |
| title_short | Stream-orbit misalignment I: The dangers of orbit-fitting |
| title_sort | stream orbit misalignment i the dangers of orbit fitting |
| work_keys_str_mv | AT sandersj streamorbitmisalignmentithedangersoforbitfitting AT binneyj streamorbitmisalignmentithedangersoforbitfitting |