Radial distribution and strong lensing statistics of satellite galaxies and substructure using high resolution LCDM hydrodynamical simulations

摘要

We analyse the number density and radial distribution of substructures andsatellite galaxies using cosmological simulations that follow the gas dynamicsof a baryonic component, including shock heating, radiative cooling and starformation within the hierarchical concordance LCDM model. We find that thedissipation of the baryons greatly enhances the survival of subhaloes,expecially in the galaxy core, resulting in a radial distribution of satellitegalaxies that closely follows the overall mass distribution in the inner partof the halo. Hydrodynamical simulations are necessary to resolve the adiabaticcontraction and dense cores of galaxies, resulting in a total number ofsatellites a factor of two larger than found in pure dark matter simulation, ingood agreement with the observed spatial distribution of satellite galaxieswithin galaxies and clusters. Convergence tests show that the coreddistribution found by previous authors in pure N-body simulations was due tophysical overmerging of dark matter only structures. We proceed to use a ray-shooting technique in order to study the impact ofthese additional substructures on the number of violations of the cusp causticmagnification relation. We develop a new approach to try to disentangle theeffect of substructures from the intrinsic discreteness of N-Body simulations.Even with the increased number of substructures in the centres of galaxies, weare not able to reproduce the observed high numbers of discrepancies observedin the flux ratios of multiply lensed quasars.