riassunto2

Speaker	Makler, Martin
Co-autors	*Gabriel Caminha (CBPF, Brazil), Juan Estrada (Fermilab, USA), Silvia Mollerach (IB/CAB, Argentina), Esteban Roulet (IB/CAB, Argentina)*
Talk Title	The importance of magnification bias on the abundance of gravitational arcs in galaxy clusters
Abstract	Although gravitational lensing conserves surface brightness, the magnification enhances the signal to noise of lensed images and therefore affects the detection of gravitational arcs. This produces a magnification bias that is different in nature from the one present in multiply imaged point sources. In this work we study the fraction of gravitational arcs in galaxy clusters, which is a more robust observable than the total number of arcs, since it is less sensitive to the cluster abundance. To compute the arc fraction we use a semi-analytic approach that takes into account the distribution of sources and the effects of magnification bias. We show that the magnification has a high impact on arc statistics, increasing by more than an order of magnitude the fraction of arcs. It also changes the redshift scaling of arc abundance as a function of cluster redshift, moving the peak towards higher redshifts.
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