Abstract
In this paper we investigate the strong lensing statistics in galaxy clusters. We extract dark matter haloes from the Millennium-XXL simulation, compute their Einstein radius distribution, and find a very good agreement with Monte Carlo predictions produced with the MOKA code. The distribution of the Einstein radii is well described by a log-normal distribution, with a considerable fraction of the largest systems boosted by different projection effects. We discuss the importance of substructures and triaxiality in shaping the size of the critical lines for cluster size haloes. We then model and interpret the different deviations, accounting for the presence of a Bright Central Galaxy (BCG) and two different stellar mass density profiles. We present scaling relations between weak lensing quantities and the size of the Einstein radii. Finally we discuss how sensible is the distribution of the Einstein radii on the cosmological parameters {\Omega}_M-{\sigma}_8 finding that cosmologies with higher {\Omega}_M and {\sigma}_8 possess a large sample of strong lensing clusters. The Einstein radius distribution may help distinguish Planck13 and WMAP7 cosmology at 3{\sigma}.
Highlights
Spectroscopic galaxy redshift surveys and numerical N-body simulations have revealed a large-scale distribution of matter in the Universe featuring a complex network of interconnected filamentary galaxy associations (Tormen, Moscardini & Yoshida 2004; Springel et al 2005; The Dark Energy Survey Collaboration 2005; Sousbie et al 2008; Sousbie, Pichon & Kawahara 2011; Guzzo et al 2014; Percival et al 2014; Codis, Pichon & Pogosyan 2015; Le Fevre et al 2015)
We have presented the strong lensing (SL) properties of a sample of galaxy clusters extracted from the Millennium-XXL simulation (M-XXL) simulation analysing the distribution of their Einstein radius
The results have been compared with a Monte Carlo MOKA realization of the same mass sample finding very good agreement
Summary
Spectroscopic galaxy redshift surveys and numerical N-body simulations have revealed a large-scale distribution of matter in the Universe featuring a complex network of interconnected filamentary galaxy associations (Tormen, Moscardini & Yoshida 2004; Springel et al 2005; The Dark Energy Survey Collaboration 2005; Sousbie et al 2008; Sousbie, Pichon & Kawahara 2011; Guzzo et al 2014; Percival et al 2014; Codis, Pichon & Pogosyan 2015; Le Fevre et al 2015). SLCs may constitute a peculiar class of objects While their existence is a natural consequence of General Relativity, ‘giant arcs’ – extremely distorted images of background galaxies – hosted in clusters have been discovered only 30 yr ago in the core of Abell 370, independently by Lynds & Petrosian (1986) and Soucail et al (1987). Very encouraging is the work performed by Zitrin et al (2012) on reconstructing the mass density distribution and the Einstein radius (which estimates the size of the SL region) of a large sample of SDSS clusters In this case, the ‘blind’ approach based on the assumption that light traces mass has allowed us to establish that the Einstein radius distribution of clusters with 0.1 < zl < 0.55 has a lognormal shape.
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