Colloquium on Jun. 13, 2024

Deconstruction of Galaxies: Unveiling Disks, Bulges, and Stellar Halos

Speaker: Min Du (XMU)

Venue: SWIFAR Building 2111

Time: 16:00 PM, Thursday, Jun. 13, 2024

Abstract:

With the rapid development of large-scale galaxy cosmological simulations, combined with observational data, we have a great opportunity to accurately understand the structure of galaxies and their formation mechanisms. In a series of studies, based on unsupervised machine learning algorithms, we have developed a precise, efficient, and minimally intrusive method that can extract the intrinsic structures of simulated galaxies from the kinematic phase space. By applying this method to galaxies in the IllustrisTNG simulations, we have defined the structures of galaxy disks, bulges, and stellar halos with precision, and extensively investigated the formation processes of different galaxy structures from both internal and external mechanisms. In particular, (1) from the perspective of intrinsic mechanisms, we can clearly understand the formation process of disk structures and the origin of the mass-size relation of galaxies; (2) we further investigate how the mass-size correlates with the formation time, metallicity, and central concentration of galaxies; (3) we point out that there is a serious conceptual confusion between the morphological decomposition of bulges and stellar halos, with the latter being a structure primarily generated by external mechanisms, e.g., mergers. Furthermore, we explore the impacts of specific physical mechanisms on different galaxy structures through the development of high-precision N-body + hydro simulations.

Report PPT:  SWIFAR_Min Du.pdf