The Effects of Substructure on Galaxy Cluster Mass Determinations
Abstract
Although numerous studies of individual galaxy clusters have demonstrated the presence of significant substructure, previous studies of the distribution of masses of galaxy clusters determined from optical observations have failed to explicitly correct for substructure in those systems. In this Letter I present the distributions of velocity dispersion, mean separation, and dynamical masses of clusters when substructure is eliminated from the cluster data sets. I also discuss the changes in these distributions because of the substructure correction. Comparing the masses of clusters with central galaxies before and after correction for the presence of substructure reveals a significant change. This change is driven by reductions in the mean separation of galaxies, not by a decrease in the velocity dispersions as has generally been assumed. Correction for substructure reduces most significantly the masses of systems with cool X-ray temperatures, suggesting that the use of a constant linear radius (1.5 h^01^_100_ Mpc in this study) to determine cluster membership is inappropriate for clusters spanning a range of temperatures and/or morphologies.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- June 1995
- DOI:
- 10.1086/187895
- arXiv:
- arXiv:astro-ph/9503038
- Bibcode:
- 1995ApJ...445L..81B
- Keywords:
-
- Dynamic Characteristics;
- Galactic Clusters;
- Galactic Evolution;
- Galactic Structure;
- Mass Distribution;
- Substructures;
- Velocity Distribution;
- Red Shift;
- X Ray Astronomy;
- X Ray Sources;
- Astrophysics;
- COSMOLOGY: OBSERVATIONS;
- GALAXIES: CLUSTERS: GENERAL;
- X-RAYS: GALAXIES;
- Astrophysics
- E-Print:
- LaTeX file