N-body simulation insights into the X-shaped bulge of the Milky Way: Kinematics and distance to the Galactic Centre - Archive ouverte HAL Accéder directement au contenu
Article Dans Une Revue Monthly Notices of the Royal Astronomical Society Année : 2014

N-body simulation insights into the X-shaped bulge of the Milky Way: Kinematics and distance to the Galactic Centre

Résumé

Using simulations of box/peanut- (B/P-) shaped bulges, we explore the nature of the X-shape of the Milky Way's bulge. An X-shape can be associated with a B/P-shaped bulge driven by a bar. By comparing in detail the simulations and the observations we show that the principal kinematic imprint of the X-shape is a minimum in the difference between the near and far side mean line-of-sight velocity along the minor axis. This minimum occurs at around |b| = 4°, which is close to the lower limit at which the X-shape can be detected. No coherent signature of an X-shape can be found in Galactocentric azimuthal velocities, vertical velocities or any of the dispersions. After scaling our simulations, we find that a best fit to the Bulge Radial Velocity Assay data leads to a bar angle of 15°. We also explore a purely geometric method for determining the distance to the Galactic Centre by tracing the arms of the X-shape. We find that we are able to determine this ill-known distance to an accuracy of about 5 per cent with sufficiently accurate distance measurements for the red clump stars in the arms.

Dates et versions

hal-00955946 , version 1 (05-03-2014)

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Citer

Esko Gardner, Victor P. Debattista, Annie C. Robin, Sergio Vásquez, Manuela Zoccali. N-body simulation insights into the X-shaped bulge of the Milky Way: Kinematics and distance to the Galactic Centre. Monthly Notices of the Royal Astronomical Society, 2014, 24, pp.stt2430. ⟨10.1093/mnras/stt2430⟩. ⟨hal-00955946⟩
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