Evolution of the properties of brightest galaxies of clusters and groups since the last 10 Gyrs

by Aline Chu

Friday 24 Nov 2023, 10:30 → 11:30 Europe/Stockholm

LC61 (AlbaNova Main Building)

Galaxy clusters are the largest gravitationally bound structures of the Universe. At the center of these clusters reside the most massive galaxies observable today, Brightest Cluster Galaxies (BCGs). BCGs are the final products of 10 Gyrs of consecutive galactic mergers in the densest regions of the cosmic web. They are excellent tracers of cluster formation, and ideal to study the impact of environmental processes on galactic formation.

The characterization of the physical properties of BCGs is important to obtain better knowledge of these galaxies. We have built new catalogues of BCGs which have allowed us to conduct a deeper analysis of the formation of BCGs, thanks to the bigger statistics we reached.

We find BCGs have shown a lack of evolution of their sizes and luminosities in the last 10 Gyrs, hinting at an earlier formation epoch and absence of recent significant growth. Their structural properties, however, may have changed over time, as hinted by the detection of an envelope only at recent epoch. We also compare the evolution of BCGs and the brightest galaxies of less dense environments such as galaxy groups or more special systems such as fossil groups (FGs). We find that brightest galaxies of FGs evolve more similarly to BCGs of clusters than brightest galaxies of normal groups of galaxies, as inferred from their Kormendy relations.

These results may be confirmed with the future Rubin-LSST survey which will observe the entire southern sky at even further lookback times, providing us with images of unprecedented depth.