Oral Presentation

Merger Rate of MaNGA Brightest Cluster Galaxies

Author(s): Yun-Hsin Hsu(ASIAA/NTHU), Yen-Ting Lin(ASIAA)

Presenter: Yun-Hsin Hsu (ASIAA/NTHU)

Numerical simulations of ΛCDM suggest that typical central galaxies in
massive dark matter halos, also known as the brightest cluster
galaxies (BCGs), have undergone many merging events at redshift z<1.
Observationally verifying such a prediction is not only key in
validating the ΛCDM structure formation paradigm, but also central to
our understanding of the formation of the most massive galaxies in the
universe.
In order to derive the merger rate of BCGs, we combine the measurement
of the frequency of BCGs with multiple cores, and
the merger timescale from the state-of-the-art cosmological
hydrodynamical simulations. Our BCG sample is extracted from the MaNGA
survey, which provides spatially resolved velocity information for
each of our 61 BCGs, and allows us to robustly distinguish real
associations of the cores with the main body of the BCG from chance
projections. The merger time scale is derived from the 300 Mpc box of
illustrisTNG. We trace the merging events of BCGs in the simulation,
and the time it appears as multiple-core that satisfies our
observational criteria. Combined together, we present the most robust
measurements of the BCG merger rates to date.