# The Virgo Overdensity Explained

## TL;DR

This paper proposes that the Virgo Overdensity results from a radial dwarf galaxy merger, explaining various stellar streams and debris in the Milky Way's halo, including connections to known structures like Gaia-Enceladus.

## Contribution

It introduces the Virgo Radial Merger model, linking multiple stellar streams and debris to a single radial dwarf galaxy merger event.

## Key findings

- The debris extends from 5 to 50 kpc in the Virgo region.
- The merger explains many observed stellar groups and streams.
- Debris in the Solar neighborhood resembles Gaia-Enceladus.

## Abstract

We suggest that the Virgo Overdensity (VOD) of stars in the stellar halo is the result of a radial dwarf galaxy merger that we call the Virgo Radial Merger. Because the dwarf galaxy passed very near to the Galactic center, the debris has a large range of energies but nearly zero $L_z$ angular momentum. The debris appears to extend from 5 to 50 kpc from the Sun in the Virgo region. We connect different parts of this merger debris to the Perpendicular and Parallel Streams (the Virgo Stellar Stream is associated with either or both of these streams), the Hercules-Aquila Cloud (HAC), and possibly the Eridanus Phoenix Overdensity (EriPhe). This radial merger can explain the majority of the observed moving groups of RR Lyrae and blue horizontal branch stars that have previously been identified in Virgo. This merger also produces debris in the Solar neighborhood similar to that identified as the Gaia-Enceladus or it Gaia-sausage merger. Orbits are provided for components of the Virgo Radial Merger progenitor and for debris that appears to be related to the Cocytos Stream, which was also recovered in the Virgo region.