The Evolution of Brightest Cluster Galaxies

摘要: In this contribution we review the properties of Brightest Cluster Galaxies (BCGs) and discuss impact that X-ray cluster selection is having on their use as cosmological probes. BCGs form a unique galaxy population. They are located near gravitational centre clusters most massive galaxies in universe, being some 10 times more luminous than L* systems. Historically, have been credited with small intrinsic dispersion absolute magnitudes (Δ≃0.2–0.3 mag) used standard candles to constrain parameters. Although indirect signs mass accretion out z≃1 observed, uncovering full evolutionary picture has remained an elusive goal. Studies based serendipitiously discovered samples, particularly from ROSAT, provide large numbers unbiased at z≤1. Furthermore emission guarantees presence gravitationally bound potential well information can be locate centroids clusters, aiding identification BCG. We show important consequences for studies distance determination large-scale streaming flows optical BCGs. Recent results selected differences near-IR BCG environment; such those Lx≥1.9×1044erg s-1 brighter uniform low-Lx counterparts. The highLx systems no evidence undergone growth, whereas low Lx widerrange evolution, grown by factor 4 ormore since z≃1. These direct indication howa single homogeneous population evolves challenge simple semi-analytical hierarchical models. If future observations high redshift seriously theory then better predictions process required.