10.3.4 Radial velocity distributions

Radial velocity distributions are computed for data and simulations separately, then combined and inter-compared. Absolute difference between Gaia DR2 and GOG18 simulation of the mean and standard deviations of the radial velocities are computed. The maps are shown Figure 10.28 for 2 magnitude ranges. The mean radial velocity as a function of magnitude for Gaia DR2 data and for GOG simulations are given Figure 10.29. We see that there is no systematic significant difference between model and data, at least not that can be attributed to the data themselves. The data show clearly the Galactic rotation as expected.

Figure 10.28: Mean radial velocities computed in HEALPix bins in the magnitude ranges 9<G<10 (top row) and 11<G<12 (bottom row) for Gaia DR2 (left column), GOG (middle column), and the difference (right column). The unit is  km s-1.
Figure 10.29: Mean radial velocities computed as a function of magnitude for Gaia DR2 data (blue circles) and GOG simulation (green squares) in three latitude ranges: Galactic pole, |b|>50 ∘(left), Intermediate latitudes 20<|b|<70 ∘(middle), and the Galactic plane |b|<20 ∘(right). Filled symbols are for the northern hemisphere, open symbols for the Southern one. The unit is  km s-1.