Fourteen candidate RR Lyrae star streams in the inner Galaxy

TL;DR

This study identifies fourteen candidate RR Lyrae star streams in the inner Galaxy using the GC3 method, revealing mostly orphan streams and providing a new Python library for stream footprints.

Contribution

The paper applies a novel stream-finding method to RR Lyrae stars, discovering new candidate streams and offering a publicly available library for stream footprints.

Findings

Two streams detected at >4σ confidence

Twelve streams detected at >3.5σ confidence

Most streams are candidate 'orphan' streams, not associated with known clusters

Abstract

We apply the GC3 stream-finding method to RR Lyrae stars (RRLS) in the Catalina survey. We find two RRLS stream candidates at $>4\sigma$ confidence and another 12 at $>3.5\sigma$ confidence over the Galactocentric distance range $4 < D/{\rm kpc} < 26$. Of these, only two are associated with known globular clusters (NGC 1261 and Arp2). The remainder are candidate `orphan' streams, consistent with the idea that globular cluster streams are most visible close to dissolution. Our detections are likely a lower bound on the total number of dissolving globulars in the inner galaxy, since many globulars have few RRLS while only the brightest streams are visible over the Galactic RRLS background, particularly given the current lack of kinematical information. We make all of our candidate streams publicly available and provide a new GALSTREAMS Python library for the footprints of all known streams and overdensities in the Milky Way.