Binary asteroid candidates in Gaia DR3 astrometry

TL;DR

This paper introduces a new astrometric method to identify binary asteroid candidates in Gaia DR3 data, aiming to uncover systems in size and separation ranges that are difficult to detect with traditional techniques.

Contribution

It develops a novel period detection technique based on Gaia astrometry and provides the first candidate list for binary asteroids using this method.

Findings

First sample of astrometric binary candidates from Gaia DR3.

Method successfully detects periodic signatures in orbit residuals.

Candidates to be confirmed by other observational techniques.

Abstract

Asteroids with companions constitute an excellent sample for studying the collisional and dynamical evolution of minor planets. The currently known binary population were discovered by different complementary techniques that produce, for the moment, a strongly biased distribution, especially in a range of intermediate asteroid sizes (approximately 20 to 100 km) where both mutual photometric events and high-resolution adaptive optic imaging are poorly efficient. A totally independent technique of binary asteroid discovery, based on astrometry, can help to reveal new binary systems and populate a range of sizes and separations that remain nearly unexplored. In this work, we describe a dedicated period detection method and its results for the Gaia DR3 data set. This method looks for the presence of a periodic signature in the orbit post-fit residuals. After conservative filtering and validation based on statistical and physical criteria, we are able to present a first sample of astrometric binary candidates, to be confirmed by other observation techniques such as photometric light curves and stellar occultations.