Globular Clusters in Elliptical Galaxies Luminosity Functions Colour

Globular Clusters in Elliptical Galaxies • • Luminosity Functions Colour Distribution Spatial Distribution Specific Frequency 1) 2) 3) 4) 5) 6) 7) 8) 9) Why E’s have higher SN of GCs? Are GCLFs of E’s the same as that of the Milky Way? Are GCLFS of E’s universal? Are colour distribution of E-GCs always bimodal? What is an implication of bimodal colours? What is a typical stellar population of E-GCs? How are GCs in X-ray extended E’s? Is SN correlated to any other global properties of E’s? Can merger produce young GCs? M 32 by T. M. Brown et al. (NASA)

Huge Number of GCs in E/c. D Galaxies Harris (1991) ARA&A 29, 543 i-GCs? 楕円銀河やｃD銀河には球状星団が多い

GCLFs of Various Galaxies Harris (1991) ARA&A 29, 543 銀河系、M 31、楕円銀河のGCLFが似ていることに注意

GCLFs of Ellipticals in Fornax Blakeslee & Tonry (1996) Ap. J 465, L 19 　　　NGC 1314 σ＝ 1. 35± 0. 18 　　　ｍｖ＝ 23. 80± 0. 25 NGC 1360 σ＝ 1. 30± 0. 17 　　　ｍｖ＝ 24. 05± 0. 25 　　　NGC 1399 　　　　σ＝ 1. 38± 0. 09 　　　ｍｖ＝ 23. 83± 0. 15 　　　NGC 1404 　　　　σ＝ 1. 32± 0. 14 　　　ｍｖ＝ 23. 92± 0. 20 GCLFs are universal in the Fornax cluster　

Turnover Magnitude & σ of GCLFs? Snecker & Harris (1993) AJ 105, 1358 Turnover magnitude とσとの間には相関がある。

Colour Distribution of GCs • A bimodal or multimodal colour distribution is often cited as a signature of merger origin of GCs of elliptical galaxies. • It is still uncertain if GC formation during mergers is effective enough to explain the higher SN in ellipticals than those of spiral galaxies.

Colour Distribution of M 87 & NGC 3923 GCs M 87 Whitmore et al. (1995) Ap. J 454, L 73 NGC 3923 Zepf et al. (1995) Ap. J 443, 570

GCs in Dynamically Young Elliptical Galaxies Miller et al. (1997) AJ 114, 2381 NGC 7252 若い球状星団の光度関数はPower Law。小さな星団は後に崩壊する。

GC Surface Density Slope vs SN Forbes et al. (1997) AJ 113, 1652 SNの高い楕円銀河の球状星団はより広がって分布する

No Clear Correlation with MR Blakeslee et al. (1997) AJ 114, 492 SNは銀河の絶対等級と相関しない。これはマージャー説には不都合。

Strong Correlation with Cluster Velocity Abell 2124 Dispersion Abell 2147 Blakeslee (199９) AJ 118, 1506 Abell 754 Abel 1644 銀河団の中心にある楕円銀河やｃD銀河の球状星団∝銀河団のポテンシャル