Oral Presentation
Are BCGs born special?
Presenter: Tsung-Chi Chen (ASIAA/NTU)
The most luminous galaxies in galaxy clusters, typically known as Brightest Cluster Galaxies (BCGs), are the most massive galaxies in the Universe. They possess unusual properties such as extended profile, photometric homogeneity, and central location in galaxy clusters, suggesting they may follow different evolution routes from other cluster member galaxies. In literature, two complementary statistical tests have been adopted to examine the uniqueness of BCGs, i.e., whether BCGs are simply the statistical extremes of the luminosity function of cluster galaxies or a distinct population. Using these two tests, previous studies have shown that BCGs are special up to redshift of z~1. Here we extend the analysis of BCG uniqueness by performing these tests on BCGs in the state-of-the-art cosmological hydrodynamical simulation TNG300 and the new simulation suite, TNG-Cluster, which provides better sampling at the high-mass end. Results from both tests suggest that simulated BCGs are special up to redshift z~4. In addition, we also perform similar analyses on HST and Spitzer data, showing that observed BCGs are already special at redshift z~2. In this contribution, we present our results and further discuss their implications on the "nature" vs. "nurture" issue for BCGs.
asiaa.sinica.edu.tw