Invited Presentation

On mass assembly history of galaxy clusters and their central galaxies

Author(s): Yen-Ting Lin (ASIAA)

Presenter: Yen-Ting Lin (ASIAA)

In this talk, I will report results from our investigations on the
assembly history of galaxy clusters and their central galaxies, often
known as the brightest cluster galaxies (BCGs). I will first
introduce a novel way of studying the assembly history of galaxy
clusters, based on a powerful forward-modeling method that allows us to reconstruct the initial density field and, in turn, produce a constrained simulation of the local universe, Elucid, in which structures larger than ~2Mpc can be faithfully reproduced. We are then able to utilize the halo formation history from the simulation and measure the formation time of real galaxy clusters. This allows us to detect the halo assembly bias robustly. In the second part of the talk, I will focus on the formation of the BCGs. Making use of velocity maps provided by the MaNGA integral field spectroscopy (IFS) survey, we have measured the fraction of BCGs that exhibit multiple-cores (indicating on-going merger events with satellite galaxies) for ~70 nearby clusters. Upon applying the same methodology to the cosmological hydrodynamical simulation IllustrisTNG, we find a good agreement between the real and mock measurements, suggesting that we may rely on IllustrisTNG to understand the formation history of BCGs.