期刊
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
卷 430, 期 2, 页码 1238-1246出版社
OXFORD UNIV PRESS
DOI: 10.1093/mnras/sts699
关键词
galaxies: evolution; cosmology: theory
资金
- National Science Foundation (NSF) [NSF AST 0806367, NSF AST 1108802]
- Pittsburgh Particle physics, Astrophysics and Cosmology Center (PITT PACC) at the University of Pittsburgh
- Alfred P. Sloan Foundation
- National Science Foundation [NSF-AST 1109789]
- United States Department of Energy [DE-SC0003960]
- NSF AST [08-06732]
- Direct For Mathematical & Physical Scien [0806732, 1108802] Funding Source: National Science Foundation
We investigate the potential to improve optical tracers of cluster mass by exploiting measurements of the magnitude gap, m(12), defined as the difference between the r-band absolute magnitudes of the two brightest cluster members. We find that in a mock sample of galaxy groups and clusters constructed from the Bolshoi simulation, the scatter about the mass-richness relation decreases by similar to 15-20 per cent when magnitude gap information is included. A similar trend is evident in a volume-limited, spectroscopic sample of galaxy groups observed in the Sloan Digital Sky Survey (SDSS). We find that SDSS groups with small magnitude gaps are richer than large-gap groups at fixed values of the one-dimensional velocity dispersion among group members , which we use as a mass proxy. We demonstrate explicitly that m12 contains information about cluster mass that supplements the information provided by group richness and the luminosity of the brightest cluster galaxy, L-BCG. In so doing, we show that the luminosities of the members of a group with richness N are inconsistent with the distribution of luminosities that results from N random draws from the global galaxy luminosity function. As the cosmological constraining power of galaxy clusters is limited by the precision in cluster mass determination, our findings suggest a new way to improve the cosmological constraints derived from galaxy clusters.
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