Ghostly Tributaries to the Milky Way: Charting the Halo's Stellar Streams with the Gaia DR2 catalogue

TL;DR

This paper uses Gaia DR2 data and the STREAMFINDER algorithm to map and identify stellar streams in the Milky Way's halo, revealing known and new structures that shed light on the Galaxy's formation.

Contribution

It introduces a novel application of the STREAMFINDER algorithm to Gaia DR2 data for mapping stellar streams in the Galactic halo beyond 5 kpc.

Findings

Detected a complex network of stellar streams in the halo.

Identified several new stellar streams.

Some structures may be artefacts requiring further confirmation.

Abstract

We present a panoramic map of the stellar streams of the Milky Way based upon astrometric and photometric measurements from the Gaia DR2 catalogue. In this first contribution, we concentrate on the halo at heliocentric distances beyond 5 kpc, and at Galactic latitudes $|b|>30\deg$, using the STREAMFINDER algorithm to detect structures along plausible orbits that are consistent with the Gaia proper motion measurements. We find a rich network of criss-crossing streams in the halo. Some of these structures were previously-known, several are new discoveries, but others are potentially artefacts of the Gaia scanning law and will require confirmation. With these initial discoveries, we are starting to unravel the complex formation of the halo of our Galaxy.