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OATS-UNI/TS SEMINAR
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Speaker: Massimo Viola (IFA Univ., Edinburgh, UK)

Title: Unbending the light
Date: Thursday, June 14th, 2012
Time: 11:30
Venue: Villa Bazzoni
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Abstract: Weak gravitational lensing has become in the last decades a very competitive cosmological tool to study the distribution of matter in the universe and to understand the properties of dark matter halos. Measuring lens-induced distortions in noisy galaxy images is however a very challenging task, even more so for the stringent requirements of the upcoming cosmic shear surveys (DES, KIDS, EUCLID): the goal is to measure a 1% variation in galaxy ellipticity with a multiplicative error in the permille range. I will discuss why reaching this precision is extremely difficult and I will present some new methods and ideas to tackle this problem. In the second part of the talk I will discuss about gravitational flexion. It is caused by the derivatives of the gravitational tidal field and it is potentially very important for the analysis of the dark matter distribution in gravitational lenses, such as galaxy clusters or the dark matter haloes of galaxies and to put constraints on the mass scale of dark matter particles. However the measurement of this signal and its interpretation are not trivial. I will critically discuss those aspects and I will present possible solutions.
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Contact: Stefano Borgani (DAUT)