9-13 July 2012
Africa/Johannesburg timezone
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Using Galaxy Clusters to constrain Dark Energy

Presented by Dr. David GILBANK on 12 Jul 2012 from 16:40 to 17:00
Type: Oral Presentation
Session: Astrophysics
Track: Track D1 - Astrophysics

Abstract

Understanding dark energy, the mysterious component which comprises 70% of the energy density of the Universe, is arguably the most important open question in physics. The observed number of galaxy clusters of a given mass and its evolution with cosmic time, N(M,z), provides a powerful means to measure the equation of state, w, of dark energy. In contrast to geometric tests of cosmology (such as those using Type Ia Supernovae), N(M,z) depends on both geometry _and_ growth factor, making it potentially more sensitive. In this talk I will describe an optical survey of ~10 000 galaxy clusters designed to measure N(M,z) over half the age of the Universe, and extensive on-going work to calibrate our mass proxy, optical richness. I will present first results from Multi-Object Spectroscopy (MOS) using the Robert Stobie Spectrograph on SALT to make dynamical mass measurements of these clusters.

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Location: IT 4-4


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