No Evidence for Orbital Clustering in the Extreme Trans-Neptunian Objects

TL;DR

This study analyzes whether the observed clustering of extreme trans-Neptunian objects' orbits is due to observational bias or indicates a new planet, finding no significant evidence for clustering in the data.

Contribution

The paper assesses the role of survey selection bias in ETNO orbital clustering, challenging previous claims of clustering suggesting a potential unseen planet.

Findings

ETNOs are consistent with a uniform orbital distribution

Selection bias can explain apparent clustering

No strong evidence for orbital clustering in the sample

Abstract

The apparent clustering in longitude of perihelion $\varpi$ and ascending node $\Omega$ of extreme trans-Neptunian objects (ETNOs) has been attributed to the gravitational effects of an unseen 5-10 Earth-mass planet in the outer solar system. To investigate how selection bias may contribute to this clustering, we consider 14 ETNOs discovered by the Dark Energy Survey, the Outer Solar System Origins Survey, and the survey of Sheppard and Trujillo. Using each survey's published pointing history, depth, and TNO tracking selections, we calculate the joint probability that these objects are consistent with an underlying parent population with uniform distributions in $\varpi$ and $\Omega$. We find that the mean scaled longitude of perihelion and orbital poles of the detected ETNOs are consistent with a uniform population at a level between $17\%$ and $94\%$, and thus conclude that this sample provides no evidence for angular clustering.