Migration and eccentricity damping timescales in overstable resonant planetary systems: hydrodynamic and N-body simulations

@misc{afkanpour2026migration,
  title = {{Migration and eccentricity damping timescales in overstable resonant planetary systems: hydrodynamic and N-body simulations}},
  author = {Zahra Afkanpour and Sareh Ataiee and Anna B. T. Penzlin and Alexandros Ziampras and Hadiseh Nabavinezhad and Christoph Schäfer and Hilke Schlichting and Rafael Sfair},
  howpublished = {arXiv},
  year = {2026},
  month = nov,
  doi = {10.48550/arxiv.2611.06765},
  eprint = {2611.06765},
  archivePrefix = {arXiv},
  url = {https://arxiv.org/abs/2611.06765},
  note = {CC BY 4.0},
}

TY  - UNPB
TI  - Migration and eccentricity damping timescales in overstable resonant planetary systems: hydrodynamic and N-body simulations
AU  - Zahra Afkanpour
AU  - Sareh Ataiee
AU  - Anna B. T. Penzlin
AU  - Alexandros Ziampras
AU  - Hadiseh Nabavinezhad
AU  - Christoph Schäfer
AU  - Hilke Schlichting
AU  - Rafael Sfair
PY  - 2026
DA  - 2026/11/04
PB  - arXiv
DO  - 10.48550/arxiv.2611.06765
UR  - https://arxiv.org/abs/2611.06765
AB  - Tidal interactions between planets and discs modify semimajor axes and eccentricities. These effects are represented by migration and eccentricity damping timescales in analytical and Nbody models, although they are assumed constant. This approximation is uncertain in resonant multiplanet systems, where coupled planet disc evolution can produce non-linear torque feedback. We investigate migration and eccentricity damping in two planet systems undergoing resonant and overstable evolution near the 2:1 mean motion resonance. Using hydrodynamic simulations with varying disc surface densities, viscosities, and aspect ratios, we measure both timescales from energy and angular momentum exchange between the planets and disc. We find that both timescales are time dependent and vary throughout the evolution. In resonant systems, sign reversals occur owing to eccentricity oscillations and disc torque variations. Moreover, migration timescales normalised by their expected dependence on planetary mass, disc surface density, and aspect ratio deviate between models. Likewise, the common relation between migration and eccentricity damping timescales is not recovered. We compare the hydrodynamic evolution with several Nbody approaches. Models with constant migration and damping timescales fail to reproduce the hydrodynamic evolution, whereas torque-based approaches provide better agreement. In particular, approaches including corotation torque saturation and planetary eccentricity reproduce the hydrodynamic evolution in the type I migration regime, whereas additional corrections are required when planets partially open gaps. These results show that time-dependent torque-based prescriptions provide a consistent physical link between hydrodynamic simulations and simplified Nbody models of resonant planetary systems.
ER  -