TY - JOUR
T1 - Clues to globular cluster evolution from multiwavelength observations of extragalactic systems
AU - Kundu, Arunav
AU - MacCarone, Thomas J.
AU - Zepf, Stephen E.
PY - 2007/9
Y1 - 2007/9
N2 - We present a study of the globular cluster (GC) systems of nearby elliptical and S0 galaxies at a variety of wavelengths from the X-ray to the infrared. Our analysis shows that roughly half of the low mass X-ray binaries (LMXBs), that are the luminous tracers of accreting neutron star or black hole systems, are in clusters. There is a surprisingly strong correlation between the LMXB frequency and the metallicity of the GCs, with metal-rich GCs hosting three times as many LMXBs as metal-poor ones, and no convincing evidence of a correlation with GC age so far. In some of the galaxies the LMXB formation rate varies with GC color even within the red peak of the typical bimodal cluster color distribution, providing some of the strongest evidence to date that there are metallicity variations within the metal-rich GC peak as is expected in a hierarchical galaxy formation scenario. We also note that any analysis of subtler variations in GC color distributions must carefully account for both statistical and systematic errors. We caution that some published GC correlations, such as the apparent blue-tilt or mass-metallicity effect might not have a physical origin and may be caused by systematic observational biases.
AB - We present a study of the globular cluster (GC) systems of nearby elliptical and S0 galaxies at a variety of wavelengths from the X-ray to the infrared. Our analysis shows that roughly half of the low mass X-ray binaries (LMXBs), that are the luminous tracers of accreting neutron star or black hole systems, are in clusters. There is a surprisingly strong correlation between the LMXB frequency and the metallicity of the GCs, with metal-rich GCs hosting three times as many LMXBs as metal-poor ones, and no convincing evidence of a correlation with GC age so far. In some of the galaxies the LMXB formation rate varies with GC color even within the red peak of the typical bimodal cluster color distribution, providing some of the strongest evidence to date that there are metallicity variations within the metal-rich GC peak as is expected in a hierarchical galaxy formation scenario. We also note that any analysis of subtler variations in GC color distributions must carefully account for both statistical and systematic errors. We caution that some published GC correlations, such as the apparent blue-tilt or mass-metallicity effect might not have a physical origin and may be caused by systematic observational biases.
KW - Blue-tilt
KW - Globular cluster systems
KW - Low mass X-ray binaries
UR - http://www.scopus.com/inward/record.url?scp=43949107928&partnerID=8YFLogxK
U2 - 10.1017/S1743921308016050
DO - 10.1017/S1743921308016050
M3 - Article
AN - SCOPUS:43949107928
SN - 1743-9213
VL - 3
SP - 408
EP - 412
JO - Proceedings of the International Astronomical Union
JF - Proceedings of the International Astronomical Union
IS - S246
ER -