— Luminous tracers have been used extensively to map the large-scale matter distribution in the Universe. Similarly the dynamics of stars or galaxies can be used to estimate masses of galaxies and clusters of galaxies. However, assumptions need to be made about the dynamical state or how well galaxies trace the underlying dark matter distribution. The… CONTINUE READING
Fig. 2. – Left panel: mass reconstruction of the central region of the z = 0.83 cluster of galaxies MS1054-03 from  demonstrating that the complex mass distribution is not well described by a simple parametric model. Right panel: the azimuthally averaged tangential distortion as a function of distance to the cluster center. The drop in signal at r 20 − 50′′ before rising again is the result of the complex mass distribution seen in the mass reconstruction.