Understanding the Velocity Distribution of the Galactic Bulge with APOGEE and Gaia

We revisit the stellar velocity distribution in Galactic bulge/bar region with Apache Point Observatory Evolution Experiment DR16 and Gaia DR2, focusing particular on possible high-velocity (HV) peaks their physical origin. fit distributions two different models, namely Gauss–Hermite polynomials Gaussian mixture models (GMMs). The result of using reveals a positive correlation between mean () "skewness" (h3) distribution, possibly caused by bar. n = 2 GMM fitting symmetric longitudinal trend ??2? ?2 (the standard deviation secondary component), which is inconsistent x2 orbital family predictions. Cold could be seen at ?l? ? 6°. However, additional tangential information from Gaia, we find that HV stars bulge show similar patterns radial–tangential (VR–VT), regardless existence distinct cold peak. observed VR–VT (or VGSR–?l) are consistent predictions simple Milky Way bar model. chemical abundances ages inferred ASPCAP CANNON suggest generally as old as, if not older than, other region.