The ACS Virgo Cluster Survey. XIV. Analysis of Color-Magnitude Relations in Globular Cluster Systems

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dc.creatorMieske, Steffen
dc.creatorJordan, Andres
dc.creatorCote, Patrick
dc.creatorKissler-Patig, Markus
dc.creatorPeng, Eric W.
dc.creatorFerrarese, Laura
dc.creatorBlakeslee, John P.
dc.creatorMei, Simona
dc.creatorMerritt, David
dc.creatorTonry, John L.
dc.creatorWest, Michael J.
dc.date2006-09-04
dc.date.accessioned2026-07-07T10:39:58Z
dc.date.available2026-07-07T10:39:58Z
dc.descriptionWe examine the correlation between globular cluster (GC) color and magnitude using HST/ACS imaging for a sample of 79 early-type galaxies (-21.7<M_B<-15.2 mag) with accurate SBF distances from the ACS Virgo Cluster Survey. Using the KMM mixture modeling algorithm, we find a highly significant correlation, d(g-z)/dz = -0.037 +- 0.004, between color and magnitude for the subpopulation of blue GCs in the co-added GC color-magnitude diagram of the three brightest Virgo galaxies (M49, M87 and M60): brighter GCs are redder than their fainter counterparts. For the single GC systems of M87 and M60, we find similar correlations; M49 does not appear to show a significant trend. There is no correlation between (g-z) and M_z for GCs of the red subpopulation. The correlation d(g-z)/dg for the blue subpopulation is much weaker than d(g-z)/dz. Using Monte Carlo simulations, we attribute this to the fact that the blue subpopulation in M_g extends to higher luminosities than the red subpopulation, which biases the KMM fits. The correlation between color and M_z thus is a real effect. This conclusion is supported by biweight fits to the same color distributions. We identify two environmental dependencies of the color-magnitude relation: (1) the slope decreases in significance with decreasing galaxy luminosity; and (2) the slope is stronger for GCs at smaller galactocentric distances. We examine several mechanisms that might give rise to the observed color-magnitude relation: (1) presence of contaminators; (2) accretion of GCs from low-mass galaxies; (3) stochastic effects; (4) capture of field stars by individual GCs; and (5) GC self-enrichment. We conclude that self-enrichment and field-star capture, or a combination of these processes, offer the most promising means of explaining our observations.
dc.description15 pages, 12 figures, accepted for publication in the Astrophysical Journal. Uses emulateapj.cls
dc.identifierhttps://arxiv.org/abs/astro-ph/0609079
dc.identifierhttp://arxiv.org/abs/astro-ph/0609079
dc.identifierAstrophys.J.653:193-206,2006
dc.identifierdoi:10.1086/508986
dc.identifier.urihttp://salesiana.dossiersoluciones.com/handle/123456789/181218
dc.subjectAstrophysics
dc.titleThe ACS Virgo Cluster Survey. XIV. Analysis of Color-Magnitude Relations in Globular Cluster Systems
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