Ying Chi Leung

Ying Chi (Gigi) Leung  ( Hong Kong )

leung @ mpia.de

Dynamical modelling techniques for galaxies

Typical kinematic tracers for galaxies include atomic, molecular or ionised gas, and stars. Molecular gases are dynamically cold and hence serve as good tracers. Not all galaxies, however, have sufficient amount of molecular gas for this purpose; in particular, early type galaxies lack molecular gas. On the other hand, stars are present in all galaxies. The high velocity dispersion makes their dynamical analysis non-trivial. Therefore, in order to recover the circular velocities and the underlying mass profile by using stellar kinematics, we need to apply dynamical modelling techniques. The commonly used techniques include Asymmetric Drift Correction (ADC), Jeans Axisymmetirc Models (JAM) and Schwarzschild Models. These models make different assumptions on the spatial distribution of stars, the gravitational potential and/or the velocity when deriving the mass profiles. It is therefore important to verify these methods and assumptions by cross-checking the circular velocity extracted from stellar kinematics using different methods, as well as from other kinematic tracers. For a sample of 60 galaxies, we compare the circular velocities extracted using CO and stellar kinematics. It is, for the first time, possible to do this comparison over a large and homogeneous sample thanks to two galaxy surveys: the EDGE survey for CO gas and the CALIFA survey for stars. Our sample covers galaxies of a wide range of masses and morphological types, allowing us to understand the regime over which the underlying assumption of different dynamical models hold or fail, This will in turn give us insights into the dynamical structures of galaxies across the Hubble types

Supervisors:  Ryan Leaman / Glenn van de Ven  ( MPIA )

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