The gravitational potential of spiral perturbations - I. The 2D (razor-thin) case
I developed an efficient numerical method for obtaining the gravitational potential of razor-thin spiral perturbations and used it to assess the standard tight-winding approximation, which is found to be reasonably accurate for pitch angles α ≲ 20°. I derived the analytic potential of razor-thin log...
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| Main Author: | |
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| Format: | Article (Journal) |
| Language: | English |
| Published: |
October 2025
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| In: |
Astronomy and astrophysics
Year: 2025, Volume: 702, Pages: 1-16 |
| ISSN: | 1432-0746 |
| DOI: | 10.1051/0004-6361/202555980 |
| Online Access: | Verlag, kostenfrei, Volltext: https://doi.org/10.1051/0004-6361/202555980 Verlag, kostenfrei, Volltext: https://www.aanda.org/articles/aa/abs/2025/10/aa55980-25/aa55980-25.html 
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| Author Notes: | Walter Dehnen |
| Summary: | I developed an efficient numerical method for obtaining the gravitational potential of razor-thin spiral perturbations and used it to assess the standard tight-winding approximation, which is found to be reasonably accurate for pitch angles α ≲ 20°. I derived the analytic potential of razor-thin logarithmic spirals with an arbitrary power-law amplitude. Approximating a spiral locally by one of these models provides a second-order tight-winding approximation that predicts the phase offset between the spiral potential and density, the resulting radially increasing pitch of the potential, and the nonlocal outward angular-momentum transport by gravitational torques. Beyond the inner and outer edge of a spiral with m arms, its potential is not winding (α = 90°), decays like R m and R −1 −m, respectively, and cannot be predicted by a local approximation. |
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| Item Description: | Online veröffentlicht: 22. Oktober 2025 Gesehen am 02.12.2025 |
| Physical Description: | Online Resource |
| ISSN: | 1432-0746 |
| DOI: | 10.1051/0004-6361/202555980 |