Friday 05/20: Using gravitational lensing to measure cluster halo shapes

Expositor: Dra. Elizabeth Gonzalez (IATE)

Date: viernes 20 de mayo, 14 hs.

Abstract: Shape measurements of dark matter halos constitute a test of the current cosmological ΛCDM paradigm, since they are sensitive to the initial density field and halo assembly. Moreover, determining halo shapes can also serve as a probe of the fundamental particle nature of dark matter. Nevertheless, deriving observational estimates of cluster dark matter halo shapes is challenging, being gravitational lensing one of the most promising observational techniques. In particular, weak lensing stacking techniques can be applied in order to obtain the median projected ellipticity of a sample of halos. If the lensing signal is combined considering the orientation of the cluster projected mass distribution, the resulting stacked mass density can be modelled to derive the projected ellipticity of the total mass surface density. In this presentation, we review how the shape of the projected surface distribution of galaxy clusters can be obtained using this technique. We present the results of observational studies and also, using simulations, we evaluate the introduced bias in deriving the projected aligned ellipticity of cluster size halos.

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