New insights on the origin of the High Velocity Peaks in the Galactic Bulge

TL;DR

This study investigates the origin of high-velocity peaks in the Milky Way bulge, suggesting they are due to large-scale midplane structures rather than the bar itself, using new simulations and orbital analysis.

Contribution

The paper introduces new test particle simulations and orbital analysis methods to distinguish the origins of high-velocity peaks in the Galactic bulge.

Findings

High-velocity peaks are linked to midplane structures, not the bar.

Simulations show these features are not associated with bar orbits.

Orbital Jacobi energy helps identify bulge building blocks.

Abstract

We provide new insight on the origin of the cold high-V$_{\rm los}$ peaks ($\sim$200 kms$^{-1}$) in the Milky Way bulge discovered in the APOGEE commissioning data \citep{Nidever2012}. Here we show that such kinematic behaviour present in the field regions towards the Galactic bulge is not likely associated with orbits that build the boxy/peanut (B/P) bulge. To this purpose, a new set of test particle simulations of a kinematically cold stellar disk evolved in a 3D steady-state barred Milky Way galactic potential, has been analysed in detail. Especially bar particles trapped into the bar are identified through the orbital Jacobi energy $E_{J}$, which allows us to identify the building blocks of the B/P feature and investigate their kinematic properties. Finally, we present preliminary results showing that the high-V$_{\rm los}$ features observed towards the Milky Way bulge are a natural consequence of a large-scale \textit{midplane} particle structure, which is unlikely associated with the Galactic bar.