Galaxy cluster merger kinematics by Rees-Sciama effect
  We discuss how to use the Rees-Sciama (RS) effect associated with merging clusters of galaxies to measure their kinematic properties. In a previous work (Rubino-Martin et al. 2004), the morphology and symmetries of the effect were examined by means of a simplified model. Here, we use realistic N-body simulations to better describe the effect, and to confirm that the signal has a characteristic quadrupole structure. From the amplitude of the signal obtained, we conclude that it is necessary to combine several cluster mergers in order to achieve a detection. Using the extended Press-Schechter formalism, we characterized the expected distribution of the parameters describing the mergers, and we used these results to generate realistic mock catalogues of cluster mergers. To optimize the extraction of the RS signal, we developed an extension of the spatial filtering method described in Haehnelt & Tegmark (1996). This extended filter has a general definition, so it can be applied in many other fields, such as gravitational lensing of the CMB or lensing of background galaxies. It has been applied to our mock catalogues, and we show that with the announced sensitivities of future experiments like the Atacama Cosmology Telescope (ACT), the South Pole Telescope (SPT) or the Atacama Large Millimeter Array (ALMA), a detection of the signal will be possible if we consider of the order of 1,000 cluster mergers. 
Matteo Maturi, Torsten Ensslin, Carlos Hernandez-Monteagudo, Jose   Alberto Rubino-Martin