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Cluster Selection and the Evolution of Brightest Cluster Galaxies
The Astrophysical Journal
|March 15, 2000
Summary
Brightest cluster galaxies (BCGs) show less mass growth than predicted, challenging galaxy formation models. This finding depends on cluster environment and when BCGs formed their stars, impacting our understanding of cosmic evolution.
Area of Science:
- Astrophysics
- Galaxy Evolution
- Cosmology
Background:
- Brightest Cluster Galaxies (BCGs) are crucial for understanding galaxy evolution.
- Previous studies on BCG evolution yielded controversial results.
- BCG luminosity is influenced by their surrounding cluster environment.
Purpose of the Study:
- To investigate the evolution of Brightest Cluster Galaxies (BCGs).
- To resolve the controversy surrounding the degree of BCG evolution.
- To compare observed BCG mass growth with predictions from galaxy formation models.
Main Methods:
- Constructing a K-band Hubble diagram for a large, X-ray-selected cluster sample.
- Analyzing BCG luminosity as a function of cluster environment.
- Assuming an Einstein-de Sitter cosmology for mass growth calculations.
Main Results:
- BCG evolution controversies stem from sample selection biases.
- BCGs in X-ray luminous clusters exhibit significantly less mass growth than predicted.
- Evidence for BCG growth is significant only if stars formed recently (z<=2.6).
Conclusions:
- Cluster environment significantly impacts BCG luminosity and evolution.
- Current semianalytic galaxy formation models may overestimate BCG mass growth.
- The formation epoch of BCG stellar populations is a key factor in their observed evolution.