A Magellanic origin for the Virgo substructure

TL;DR

This paper investigates a large stellar structure in the Virgo region, proposing it may originate from the Magellanic Clouds due to its alignment with the Magellanic Stream and possible tidal interactions.

Contribution

It presents evidence linking the Virgo substructure to the Magellanic Clouds, suggesting a Magellanic origin for the Virgo stellar features based on spatial and dynamical analysis.

Findings

The Virgo structure is confirmed in multiple surveys, not Gaia-specific.

The structure aligns with the Magellanic Stream, indicating a possible Magellanic origin.

The substructure may be debris from a disrupted dwarf galaxy or SMC-LMC tidal interaction.

Abstract

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 $12<R<27\;\mathrm{kpc}$ and extend over $2600\;\mathrm{deg}^2$ 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 $3\;\mathrm{Gyr}$ ago. If the latter then the sub-structure in Virgo may have a Magellanic origin.