The ACS Virgo Cluster Survey.: XIV.: Analysis of color-magnitude relations in globular cluster systems

被引:93
作者
Mieske, Steffen
Jordan, Andres
Cote, Patrick
Kissler-Patig, Markus
Peng, Eric W.
Ferrarese, Laura
Blakeslee, John P.
Mei, Simona
Merrit, David
Tonry, John L.
West, Michael J.
机构
[1] European So Observ, D-85748 Garching, Germany
[2] Univ Oxford, Oxford OX1 3RH, England
[3] Herzberg Inst Astrophys, Victoria, BC V9E 2E7, Canada
[4] Johns Hopkins Univ, Dept Phys & Astron, Baltimore, MD 21218 USA
[5] Washington State Univ, Dept Phys & Astron, Pullman, WA 99164 USA
[6] Rochester Inst Technol, Dept Phys, Rochester, NY 14623 USA
[7] Univ Hawaii, Inst Astron, Honolulu, HI 96822 USA
[8] Gemini Observ, So Operat Ctr, AURA, La Serena, Chile
基金
美国国家科学基金会;
关键词
galaxies : clusters : individual (Virgo); galaxies : dwarf; galaxies : fundamental parameters; galaxies : nuclei; galaxies : star clusters; globular clusters : general;
D O I
10.1086/508986
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
We examine the correlation between globular cluster (GC) color and magnitude using HSTACS 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, gamma(z) equivalent to d(g-z)/dz = -0.037 +/- 0.004, between color and magnitude for the subpopulation of blue GCs in the co-added GC colormagnitude diagram of the three brightest Virgo Cluster 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 gamma(g) equivalent to d(g-z)/dg for the blue subpopulation is much weaker than d(g-z)/dz. Using Monte Carlo simulations, we attribute this finding to the fact that the blue subpopulation in M-g extends to higher luminosities than does the red subpopulation, which biases the KMM fit results. The correlation between color and Mz thus is a real effect: this conclusion is supported by biweight fits to the same color distributions. We identify two environmental dependencies that influence the derived color-magnitude relation: (1) the slope decreases in significance with decreasing galaxy luminosity; and (2) the slope is stronger for GC populations located at smaller galactocentric distances. We examine several physical 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) the 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.
引用
收藏
页码:193 / 206
页数:14
相关论文
共 85 条
[1]   DETECTING BIMODALITY IN ASTRONOMICAL DATASETS [J].
ASHMAN, KM ;
BIRD, CM ;
ZEPF, SE .
ASTRONOMICAL JOURNAL, 1994, 108 (06) :2348-2361
[2]   THE FORMATION OF GLOBULAR-CLUSTERS IN MERGING AND INTERACTING GALAXIES [J].
ASHMAN, KM ;
ZEPF, SE .
ASTROPHYSICAL JOURNAL, 1992, 384 (01) :50-61
[3]   ARE GLOBULAR-CLUSTERS THE NUCLEI OF CANNIBALIZED DWARF GALAXIES [J].
BASSINO, LP ;
MUZZIO, JC ;
RABOLLI, M .
ASTROPHYSICAL JOURNAL, 1994, 431 (02) :634-639
[4]   Young star cluster complexes in NGC 4038/39 - Integral field spectroscopy using VIMOS-VLT [J].
Bastian, N ;
Emsellem, E ;
Kissler-Patig, M ;
Maraston, C .
ASTRONOMY & ASTROPHYSICS, 2006, 445 (02) :471-483
[5]   On the formation of globular cluster systems in a hierarchical Universe [J].
Beasley, MA ;
Baugh, CM ;
Forbes, DA ;
Sharples, RM ;
Frenk, CS .
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, 2002, 333 (02) :383-399
[6]   MEASURES OF LOCATION AND SCALE FOR VELOCITIES IN CLUSTERS OF GALAXIES - A ROBUST APPROACH [J].
BEERS, TC ;
FLYNN, K ;
GEBHARDT, K .
ASTRONOMICAL JOURNAL, 1990, 100 (01) :32-46
[7]   Cluster cannibalism and scaling relations of galactic stellar nuclei [J].
Bekki, K ;
Couch, WJ ;
Drinkwater, MJ ;
Shioya, Y .
ASTROPHYSICAL JOURNAL, 2004, 610 (01) :L13-L16
[8]   Formation of ω Centauri from an ancient nucleated dwarf galaxy in the young Galactic disc [J].
Bekki, K ;
Freeman, KC .
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, 2003, 346 (02) :L11-L15
[9]   Galaxy threshing and the origin of ultra-compact dwarf galaxies in the Fornax cluster [J].
Bekki, K ;
Couch, WJ ;
Drinkwater, MJ ;
Shioya, Y .
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, 2003, 344 (02) :399-411
[10]   Capture of field stars by globular clusters in dense bulge regions [J].
Bica, E ;
Dottori, H ;
De Oliveira, IR ;
Ortolani, S ;
Barbuy, B .
ASTROPHYSICAL JOURNAL, 1997, 482 (01) :L49-L51