Candidate Distant Trans-Neptunian Objects Detected by the New Horizons Subaru TNO Survey

TL;DR

This paper reports the discovery of 239 distant trans-Neptunian objects using the Subaru Telescope, revealing an unexpected abundance of objects beyond 70 au that could reshape understanding of the outer Solar System.

Contribution

It introduces new machine learning techniques to manage false positives in shift and stack routines and reports a significant overabundance of distant objects beyond 70 au.

Findings

Discovered 239 trans-Neptunian objects, including very faint ones.

Found an overabundance of objects beyond 70 au compared to models.

Suggests a previously unrecognized population of distant Solar System objects.

Abstract

We report the detection of 239 trans-Neptunian Objects discovered through the on-going New Horizons survey for distant minor bodies being performed with the Hyper Suprime-Cam mosaic imager on the Subaru Telescope. These objects were discovered in images acquired with either the r2 or the recently commissioned EB-gri filter using shift and stack routines. Due to the extremely high stellar density of the search region down stream of the spacecraft, new machine learning techniques had to be developed to manage the extremely high false positive rate of bogus candidates produced from the shift and stack routines. We report discoveries as faint as r2$\sim26.5$. We highlight an overabundance of objects found at heliocentric distances $R\gtrsim70$~au compared to expectations from modelling of the known outer Solar System. If confirmed, these objects betray the presence of a heretofore unrecognized abundance of distant objects that can help explain a number of other observations that otherwise remain at odds with the known Kuiper Belt, including detections of serendipitous stellar occultations, and recent results from the Student Dust Counter on-board the New Horizons spacecraft.