Oral Presentation

The Nascence of Disk Galaxies : Angular Momentum and its Impact on the Mass-Size Relation”

Author(s): Ji Hoon Kim (SNU)

Presenter: Ji Hoon Kim (Astronomy Research Center, Seoul National University)

In the standard galaxy formation, galactic disks from out of primordial gas due to density fluctuation that slowly cools out of a hot gaseous halo conserving its specific angular momentum, and forms a disc with stellar and gaseous components at the center of the potential well of a dark matter halo. Therefore, fundamental properties of galactic disks, such as central surface density, and disk scale length, must reflect the physical conditions of their formation. However, it is still unclear what decides these properties: leading hypotheses under the current galaxy formation paradigm are either that amplitudes of initial density fluctuations decide central surface density of galactic disks, or that specific angular momenta of dark matter haloes differentiate sizes of galactic disks. However, it is not trivial to satisfy the fundamental properties observed from nearby disk galaxies, such as the baryonic Tully-Fisher relation, the central density relation, etc. Based on SPARC data, we investigate correlations between specific angular momentum, central surface brightness, disk scale length and other properties to see how disk galaxy formation hypotheses hold. We also study if small, or large scale environment is the culprit for shortfall of these hypotheses.