Iorio et al. (2018) mapped out the Milky Way halo using a sample of RR Lyrae stars drawn from a cross-match of Gaia with 2MASS. We investigate the significant residual in their model which we constrain to lie at Galactocentric radii 12<R<27kpc and extend over 2600deg2 of the sky. A counterpart of this structure exists in both the Catalina Real Time Survey and the sample of RR Lyrae variables identified in Pan-STARRS by Hernitschek et al. (2016), demonstrating that this structure is not caused by the spatial inhomogeneity of Gaia. The structure is likely the Virgo Stellar Stream and/or Virgo Over-Density. We show the structure is aligned with the Magellanic Stream and suggest that it is either debris from a disrupted dwarf galaxy that was a member of the Vast Polar Structure or that it is SMC debris from a tidal interaction of the SMC and LMC 3Gyr ago. If the latter then the sub-structure in Virgo may have a Magellanic origin.
@article{arxiv.1711.07493,
title = {A Magellanic origin for the Virgo substructure},
author = {D. Boubert and V. Belokurov and D. Erkal and G. Iorio},
journal= {arXiv preprint arXiv:1711.07493},
year = {2018}
}