Weak gravitational lensing as a probe of physical properties of substructures in dark matter halos

We propose a novel method to select satellite galaxies in outer regions of galaxy groups or clusters using weak gravitational lensing. The method is based on the theoretical expectation that the tangential shear pattern around satellite galaxies would appear with negative values at an offset distance from the center of the main halo. We can thus locate the satellite galaxies statistically with an offset distance of several lensing smoothing scales by using the standard reconstruction of surface mass density maps from weak lensing observation. We test the idea using high-resolution cosmological simulations. We show that subhalos separated from the center of the host halo are successfully located even without assuming the position of the center. For a number of such subhalos, the characteristic mass and offset length can be also estimated on a statistical basis. We perform a Fisher analysis to show how well upcoming weak lensing surveys can constrain the mass density profile of satellite galaxies. In the case of the Large Synoptic Survey Telescope with a sky coverage of 20,000 square degrees, the mass of the member galaxies in the outer region of galaxy clusters can be constrained with an accuracy of ~0.1 dex for galaxy clusters with mass 10^14 Msun/h at z=0.15. Finally we explore the detectability of tidal stripping features for subhalos having a wide range of masses of 10^11-10^13 Msun/h.