Yu, Hang and Weinberg, Nevin N. and Arras, Phil (2021) Tides in the High-eccentricity Migration of Hot Jupiters: Triggering Diffusive Growth by Nonlinear Mode Interactions. Astrophysical Journal, 917 (1). Art. No. 31. ISSN 0004-637X. doi:10.3847/1538-4357/ac0a79. https://resolver.caltech.edu/CaltechAUTHORS:20210813-181204556
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Abstract
High-eccentricity migration is a possible formation channel for hot Jupiters. However, in order for it to be consistent with the observed population of planets, tides must circularize the orbits in an efficient manner. A potential mechanism for such rapid circularization is the diffusive growth of the tidally driven planetary f-mode. Such growth occurs if the f-mode phase at pericenter varies chaotically from one pericenter passage to the next. Previous studies focused on the variation of the orbital period due to tidal back-reaction on the orbit as the source of chaos. Here we show that nonlinear mode interactions can also be an important source. Specifically, we show that nonlinear interactions between a parent f-mode and daughter f-/p-modes induce an energy-dependent shift in the oscillation frequency of the parent. This frequency shift varies randomly from orbit to orbit because the parents' energy varies. As a result, the parents' phase at pericenter varies randomly, which we find can trigger it to grow diffusively. We show that the phase shift induced by nonlinear mode interactions in fact dominates the shift induced by tidal back-reaction and lowers the one-kick energy threshold for diffusive growth by about a factor of 5 compared to the prediction from the linear theory. For a given pericenter distance, this reduces the semimajor axis needed to trigger diffusive growth from ≳2 au to ≃1 au. Nonlinear interactions could thus enhance the formation rate of hot Jupiters through the high-eccentricity migration channel and potentially mitigate the discrepancy between the observed and predicted occurrence rates for close-in gas giants as compared to those farther from the star.
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Additional Information: | © 2021. The American Astronomical Society. Received 2021 April 11; revised 2021 May 28; accepted 2021 June 9; published 2021 August 12. We thank Dong Lai, Jim Fuller, Yanqin Wu, Fei Dai, Heather Knutson, and the anonymous referee for helpful discussions and comments during the conception and the development of this study. This work was supported by NSF AST-2054353. H.Y. acknowledges the support of the Sherman Fairchild Foundation. | |||||||||
Group: | TAPIR, Walter Burke Institute for Theoretical Physics | |||||||||
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Subject Keywords: | Exoplanets; Hot Jupiters; Exoplanet tides; Exoplanet migration; Hydrodynamics | |||||||||
Issue or Number: | 1 | |||||||||
Classification Code: | Unifed Astronomy Thesaurus concepts: Exoplanets (498); Hot Jupiters (753); Exoplanet tides (497); Exoplanet migration (2205); Hydrodynamics (1963) | |||||||||
DOI: | 10.3847/1538-4357/ac0a79 | |||||||||
Record Number: | CaltechAUTHORS:20210813-181204556 | |||||||||
Persistent URL: | https://resolver.caltech.edu/CaltechAUTHORS:20210813-181204556 | |||||||||
Official Citation: | Hang Yu et al 2021 ApJ 917 31 | |||||||||
Usage Policy: | No commercial reproduction, distribution, display or performance rights in this work are provided. | |||||||||
ID Code: | 110268 | |||||||||
Collection: | CaltechAUTHORS | |||||||||
Deposited By: | George Porter | |||||||||
Deposited On: | 13 Aug 2021 21:12 | |||||||||
Last Modified: | 13 Aug 2021 21:12 |
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