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arXiv · 1806.02832

Transient spiral structure and the disc velocity substructure in Gaia DR2

Jason A. S. Hunt·Jack Hong·Jo Bovy·Daisuke Kawata·Robert J. J. Grand
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Abstract

The second data release from ESA's Gaia mission has revealed many ridge-like structures in the velocity distribution of the Milky Way. We show that these can arise naturally from winding transient spiral structure that is commonly seen in N-body simulations of disk galaxies. We construct test particle models of the winding spiral structure, and compare the resulting distribution of orbits with the observed two-dimensional velocity distribution in the extended solar neighbourhood and with the distribution of rotational velocities over 8 kpc along the Sun--Galactic-centre--Galactic anti-centre line. We show that the ridges in these observations are well reproduced by the winding spiral model. Additionally, we demonstrate that the transient winding spiral potential can create a Hercules-like feature in the kinematics of the solar neighbourhood, either alone, or in combination with a long-slow bar potential.

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Jason A. S. Hunt, Jack Hong, Jo Bovy, Daisuke Kawata, Robert J. J. Grand. 2018-06-07. Transient spiral structure and the disc velocity substructure in Gaia DR2. https://doi.org/10.1093/mnras/sty2532

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