Effects of Planetesimal Scattering: Explaining the Observed Offsets from Period Ratios 3:2 and 2:1. (arXiv:2209.05138v2 [astro-ph.EP] UPDATED)
<a href="http://arxiv.org/find/astro-ph/1/au:+Ghosh_T/0/1/0/all/0/1">Tuhin Ghosh</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Chatterjee_S/0/1/0/all/0/1">Sourav Chatterjee</a>
The observed deficit and excess of adjacent planet pairs with period ratios
narrow and wide of 3:2 and 2:1, the nominal values for the corresponding mean
motion resonances (MMRs), have intrigued many. Previously, using a suite of
simulations, Chatterjee & Ford (2015) showed that the excess above the 2:1 MMR
can be naturally explained if planet pairs, initially trapped in the 2:1 MMR,
dynamically interact with nearby planetesimals in a disk. We build on this work
by: a) updating the census of discovered planet pairs, b) extending the study
to initially non-resonant as well as resonant planet pairs, c) using initial
planet and orbital properties directly guided by those observed, and d)
extending the initial period ratios to include both 2:1 and 3:2. We find that
1) interactions with planetesimals typically increase the period ratios of both
initially resonant and non-resonant planet pairs; 2) starting from an initially
flat period ratio distribution for systems across 3:2 and 2:1, these
interactions can naturally create the deficits observed narrow of these period
ratios; 3) contribution from initially resonant planet pairs is needed to
explain the observed levels of excess wide of 3:2; 4) a mixture model where
about 25% (1%) planet pairs were initially trapped into 3:2 (2:1) MMRs is
favored to explain both the observed deficit and excess of systems across these
period ratios, however, up to a few percent of planet pairs are expected to
remain in MMR today.
The observed deficit and excess of adjacent planet pairs with period ratios
narrow and wide of 3:2 and 2:1, the nominal values for the corresponding mean
motion resonances (MMRs), have intrigued many. Previously, using a suite of
simulations, Chatterjee & Ford (2015) showed that the excess above the 2:1 MMR
can be naturally explained if planet pairs, initially trapped in the 2:1 MMR,
dynamically interact with nearby planetesimals in a disk. We build on this work
by: a) updating the census of discovered planet pairs, b) extending the study
to initially non-resonant as well as resonant planet pairs, c) using initial
planet and orbital properties directly guided by those observed, and d)
extending the initial period ratios to include both 2:1 and 3:2. We find that
1) interactions with planetesimals typically increase the period ratios of both
initially resonant and non-resonant planet pairs; 2) starting from an initially
flat period ratio distribution for systems across 3:2 and 2:1, these
interactions can naturally create the deficits observed narrow of these period
ratios; 3) contribution from initially resonant planet pairs is needed to
explain the observed levels of excess wide of 3:2; 4) a mixture model where
about 25% (1%) planet pairs were initially trapped into 3:2 (2:1) MMRs is
favored to explain both the observed deficit and excess of systems across these
period ratios, however, up to a few percent of planet pairs are expected to
remain in MMR today.
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