The Metallicity Distributions of Globular Cluster Systems in Other Galaxies
Abstract
Although the color distributions of globular cluster systems around other galaxies are well known to be bimodal, the true metallicity distributions have been poorly defined. As part of the SLUGGS survey of nearby early-type galaxies and their globular cluster systems we have used the DEIMOS multi-object spectrograph on Keck to obtain spectra of thousands of globular clusters. We have been able to measure the strength of the near infrared calcium triplet in over 900 globular clusters in twelve galaxies. One of strongest spectral features in the optical and near infrared, the calcium triplet is sensitive to the total metallicity but not age, α-element enhancement or horizontal branch morphology in integrated stellar populations. Using the calcium triplet strengths we derive metallicities for over 900 globular clusters in 11 galaxies - the largest sample of spectroscopic globular cluster metallicities yet assembled. Our calcium triplet based metallicities show good agreement with literature metallicities derived using traditional Lick spectral index analysis. We find that massive galaxies do have bimodal globular cluster metallicity distributions similar to their colour distributions. We will briefly discuss the implications of our work for galaxy formation models.
- Publication:
-
American Astronomical Society Meeting Abstracts #221
- Pub Date:
- January 2013
- Bibcode:
- 2013AAS...22142501U