Explaining the Color Distributions of Globular Cluster Systems in Elliptical Galaxies

The colors of globular clusters in most of large elliptical galaxies are bimodal. This is generally taken as evidence for the presence of two cluster subpopulations that have different geneses. However, here we find that, because of the non-linear nature of the metallicity-to-color transformation, a...

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Bibliographic Details
Published in:arXiv.org 2006-03
Main Authors: Suk-Jin, Yoon, Sukyoung Ken Yi, Young-Wook, Lee
Format: Article
Language:English
Subjects:
Color
Elliptical galaxies
Galactic clusters
Galactic evolution
Globular clusters
Horizontal branch stars
Linearity
Metallicity
Nonlinearity
Space telescopes
Star & galaxy formation
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Summary:The colors of globular clusters in most of large elliptical galaxies are bimodal. This is generally taken as evidence for the presence of two cluster subpopulations that have different geneses. However, here we find that, because of the non-linear nature of the metallicity-to-color transformation, a coeval group of old clusters with a unimodal metallicity spread can exhibit color bimodality. The models of cluster colors indicate that the horizontal-branch stars are the main drivers behind the empirical non-linearity. We show that the scenario gives simple and cohesive explanations for all the key observations, and could simplify theories of elliptical galaxy formation.
ISSN:2331-8422
DOI:10.48550/arxiv.0601526