OSSOS XVII: Probing the Distant Solar System with Observed Scattering TNOs. (arXiv:1905.09286v1 [astro-ph.EP])

OSSOS XVII: Probing the Distant Solar System with Observed Scattering TNOs. (arXiv:1905.09286v1 [astro-ph.EP])
<a href="http://arxiv.org/find/astro-ph/1/au:+Kaib_N/0/1/0/all/0/1">Nathan A. Kaib</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Pike_R/0/1/0/all/0/1">Rosemary Pike</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Lawler_S/0/1/0/all/0/1">Samantha Lawler</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kovalik_M/0/1/0/all/0/1">Maya Kovalik</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Brown_C/0/1/0/all/0/1">Christopher Brown</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Alexandersen_M/0/1/0/all/0/1">Mike Alexandersen</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Bannister_M/0/1/0/all/0/1">Michele T. Bannister</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Gladman_B/0/1/0/all/0/1">Brett J. Gladman</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Petit_J/0/1/0/all/0/1">Jean-Marc Petit</a>

Most known trans-Neptunian objects (TNOs) gravitationally scattering off the
giant planets have orbital inclinations consistent with an origin from the
classical Kuiper belt, but a small fraction of these “scattering TNOs” have
inclinations that are far too large (i > 45 deg) for this origin. These
scattering outliers have previously been proposed to be interlopers from the
Oort cloud or evidence of an undiscovered planet. Here we test these hypotheses
using N-body simulations and the 69 centaurs and scattering TNOs detected in
the Outer Solar Systems Origins Survey and its predecessors. We confirm that
observed scattering objects cannot solely originate from the classical Kuiper
belt, and we show that both the Oort cloud and a distant planet generate
observable highly inclined scatterers. Although the number of highly inclined
scatterers from the Oort Cloud is ~3 times less than observed, Oort cloud
enrichment from the Sun’s galactic migration or birth cluster could resolve
this. Meanwhile, a distant, low-eccentricity 5 Earth-mass planet replicates the
observed fraction of highly inclined scatterers, but the overall inclination
distribution is more excited than observed. Furthermore, the distant planet
generates a longitudinal asymmetry among detached TNOs that is less extreme
than often presumed, and its direction reverses across the perihelion range
spanned by known TNOs. More complete models that explore the dynamical origins
of the planet are necessary to further study these features. With observational
biases well-characterized, our work shows that the orbital distribution of
detected scattering bodies is a powerful constraint on the unobserved distant
solar system.

Most known trans-Neptunian objects (TNOs) gravitationally scattering off the
giant planets have orbital inclinations consistent with an origin from the
classical Kuiper belt, but a small fraction of these “scattering TNOs” have
inclinations that are far too large (i > 45 deg) for this origin. These
scattering outliers have previously been proposed to be interlopers from the
Oort cloud or evidence of an undiscovered planet. Here we test these hypotheses
using N-body simulations and the 69 centaurs and scattering TNOs detected in
the Outer Solar Systems Origins Survey and its predecessors. We confirm that
observed scattering objects cannot solely originate from the classical Kuiper
belt, and we show that both the Oort cloud and a distant planet generate
observable highly inclined scatterers. Although the number of highly inclined
scatterers from the Oort Cloud is ~3 times less than observed, Oort cloud
enrichment from the Sun’s galactic migration or birth cluster could resolve
this. Meanwhile, a distant, low-eccentricity 5 Earth-mass planet replicates the
observed fraction of highly inclined scatterers, but the overall inclination
distribution is more excited than observed. Furthermore, the distant planet
generates a longitudinal asymmetry among detached TNOs that is less extreme
than often presumed, and its direction reverses across the perihelion range
spanned by known TNOs. More complete models that explore the dynamical origins
of the planet are necessary to further study these features. With observational
biases well-characterized, our work shows that the orbital distribution of
detected scattering bodies is a powerful constraint on the unobserved distant
solar system.

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