The origin and fate of the Gaia phase-space snail

Understand

The Gaia snail is a spiral feature in the distribution of solar-neighbourhood stars in position and velocity normal to the Galactic midplane.

• The snail probably arises from phase mixing of gravitational disturbances that perturbed the disc in the distant past.
• The most common hypothesis is that the strongest disturbance resulted from a passage of the Sagittarius dwarf galaxy close to the solar neighbourhood.
• In this paper we investigate the alternative hypothesis that the snail is created by many small disturbances rather than one large one, that is, by Gaussian noise in the gravitational potential.