paper

A Kiloparsec-Scale Nuclear Stellar Disk in the Milky Way as a Possible Explanation of the High Velocity Peaks in the Galactic Bulge

arXiv:1507.01433 · doi:10.1088/2041-8205/812/1/L16

Abstract

The Apache Point Observatory Galactic Evolution Experiment has measured the stellar velocities of red giant stars in the inner Milky Way. We confirm that the line of sight velocity distributions (LOSVDs) in the mid-plane exhibit a second peak at high velocities, whereas those at |b| = 2degrees do not. We use a high resolution simulation of a barred galaxy, which crucially includes gas and star formation, to guide our interpretation of the LOSVDs. We show that the data are fully consistent with the presence of a thin, rapidly rotating, nuclear disk extending to ~1 kpc. This nuclear disk is orientated perpendicular to the bar and is likely to be composed of stars on x2 orbits. The gas in the simulation is able to fall onto such orbits, leading to stars populating an orthogonal disk.

Published in ApJL, volume 812, L16. This version changes significantly to reflect other literature since the paper was submitted and the referee's comments. The fundamental result remains the same, that the presence of a 1 kpc nuclear disk in the Milky Way is able to explain the high velocity peaks seen by the APOGEE survey

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