On the nature of the stellar bridge between Leo IV and Leo V

TL;DR

This study confirms a stellar overdensity between Leo IV and Leo V, likely associated with the Virgo overdensity, based on deep Subaru observations revealing an extended stellar structure at about 20 kpc.

Contribution

The paper provides an improved analysis of the stellar bridge between Leo IV and Leo V using wider and deeper Subaru data, suggesting a connection to the Virgo overdensity.

Findings

Confirmed stellar overdensity between Leo IV and Leo V

Detected an extended stellar structure at ~20 kpc

Suggests association with the Virgo overdensity

Abstract

We present a revised analysis of a speculated stellar bridge between the Milky Way dwarf galaxies Leo IV and Leo V. Using data acquired with Subaru/Suprime-Cam over a 1deg x 4deg field encompassing the two satellites and the region in between, we confirm our previous detection of a stellar overdensity between Leo IV and Leo V (de Jong et al. 2010). The larger area coverage and improved depth of our current dataset allow for an improved analysis of the stellar overdensity that had previously appeared to bridge the two galaxies. A main-sequence turn-off feature visible in the stacked colour-magnitude diagram of the contiguously observed Subaru fields reveals an extended stellar structure at a distance of approximately 20 kpc. Its angular proximity to the Virgo overdensity, as well as a good correspondence in distance and metallicity, suggests that the smaller structure we detect may be associated with the much larger Virgo stellar overdensity.