# The Galaxy Content of SDSS Clusters and Groups

**Authors:** Sarah M. Hansen, Erin S. Sheldon, Risa H. Wechsler, Benjamin P. Koester  
**arXiv:** [0710.3780](https://arxiv.org/abs/0710.3780)  
**Date:** 2007-10-22  
**Summary page:** https://www.summarizepaper.com/en/paper/0710.3780v1/

## Key points

- Study uses imaging data from Sloan Digital Sky Survey and MaxBCG algorithm
- Focus on relationship between cluster properties and luminosity of Brightest Cluster Galaxy (BCG)
- Analysis conducted within redshift range of 0.1 < z < 0.3
- Red and blue satellite galaxies show weak dependence on cluster richness in terms of luminosity function
- Shape of satellite luminosity function remains constant for brighter magnitudes, but changes in mix of faint red and blue galaxies
- Fraction of red satellites influenced by cluster-centric distance, galaxy luminosity, and cluster mass
- Strong correlation between BCG luminosity and cluster richness
- BCG luminosity follows Gaussian distribution with sigma_{log L} ~ 0.17 for massive clusters at fixed richness levels
- Ratios of BCG luminosity to total cluster luminosity and characteristic satellite luminosity scale with cluster richness

## Summary

The study utilizes imaging data from the Sloan Digital Sky Survey to analyze the galaxy population in groups and clusters identified by the MaxBCG algorithm. The researchers focus on understanding the relationship between various cluster properties and the luminosity of the Brightest Cluster Galaxy (BCG), as well as the distribution of satellite galaxy luminosity and color. The analysis is conducted within a redshift range of 0.1 < z < 0.3, allowing for measurements across different cluster richness, radius, and redshift bins. The findings reveal that within a specific radius (r_200) of clusters with a mass above 3e13 h-1 M_sun, both red and blue satellite galaxies exhibit a weak dependence on cluster richness in terms of their luminosity function. Additionally, it is observed that the shape of the satellite luminosity function remains constant for magnitudes brighter than ^{0.25}M_i - 5log(h) < -19, but there are significant changes in the mix of faint red and blue galaxies. The fraction of red satellites is influenced by cluster-centric distance, galaxy luminosity, and cluster mass, increasing by approximately 5% between redshifts 0.28 and 0.2 regardless of richness. Furthermore, a strong correlation is identified between BCG luminosity and cluster richness, with BCGs scaling as L_{BCG} ~ M_{200}^{0.3}. At fixed richness levels, BCG luminosity follows a Gaussian distribution with sigma_{log L} ~ 0.17 for massive clusters. The ratios of BCG luminosity to total cluster luminosity and characteristic satellite luminosity also show strong scaling with cluster richness: richer systems have BCGs that contribute less light to total light but are brighter compared to typical satellites. Overall, this study highlights how cross-correlation techniques can be used to analyze galaxy populations solely based on photometric data; providing valuable insights into the relationship between cluster properties and the luminosity and color distribution of galaxies within them which contributes to our understanding of galaxy evolution in different environments.