Friday

Galactic bars are a common morphological feature of spiral galaxies that play an important role in disc dynamics. In the Milky Way we are able to see complex dynamical processes, that are not available for us to observe in external galaxies. However, to understand better these processes and the importance of the bar in shaping them, we need to know more precisely the pattern speed of the rigid rotation of the bar. The determination of this parameter is not straight-forward due to our location within the Milky Way and resulting from its observational difficulties.

In this talk we want to present a model-independent method of the measuring of the pattern speed that is based on the continuity equation and adopted for the specific old stellar population. We will present detailed tests of the method performed on high resolution isolated N-body simulations and Milky Way analogues from hydrodynamical cosmological simulation IllustrisTNG (run TNG50). The tests were taking into the account limited sample size, spatial selection effects and approximate three-dimensional size of the bar. We will also present results of the application of this method to the kinematical data of Gaia EDR3 and compare them with the results known from the literature.