Details

Autor(en) / Beteiligte

• Bekki, Kenji
• Yahagi, Hideki
• Forbes, Duncan A

Titel

The U-shaped Distribution of Globular Cluster-specific Frequencies in a Biased Globular Cluster Formation Scenario

Ist Teil von

• The Astrophysical journal, 2006-07, Vol.645 (1), p.L29-L32

Ort / Verlag

Chicago, IL: IOP Publishing

Erscheinungsjahr

2006

Quelle

EZB Electronic Journals Library

Beschreibungen/Notizen

• Using high-resolution numerical simulations, we investigate mass- and luminosity-normalized specific frequencies (T sub(N) and S sub(N), respectively) of globular cluster systems (GCSs) in order to understand the origin of the observed U-shaped relation between S sub(N) and the V-band magnitude (M sub(V)) of their host galaxies. We adopt a biased GC formation scenario in which GC formation is truncated in galaxy halos that are virialized at a later redshift, z sub(trum). T sub(N) is derived for galaxies with present-day GCs and converted into S sub(N) for reasonable galaxy mass-to-light ratios (M/L). We find that T sub(N) depends on halo mass (M sub(h)) in the sense that T sub(N) can be larger in more massive halos with M sub(h) > 10 super(9) M sub( ), if z sub(trun) is as high as 15. However, we find that the dependence is too weak to explain the observed S sub(N)-M sub(V) relation and the wide range of S sub(N) in low-mass early-type galaxies with -20.5 mag < M sub(V) < -16.0 mag for a reasonable constant M/L. The M sub(V) dependence of S sub(N) for the low-mass galaxies can be well reproduced, if the mass-to-light ratio M sub(h)/L sub(V)8Mh super(a), where a is as steep as -1. Based on these results, we propose that the origin of the observed U-shaped S sub(N)-M sub(V) relation of GCSs can be understood in terms of the bimodality in the dependence of M sub(h)/L sub(V) on M sub(h) of their host galaxies. We also suggest that the observed large dispersion in S sub(N) in low-mass galaxies is due partly to the large dispersion in T sub(N).