Nobuhiro Okabe, Toshifumi Futamase, Masaru Kajisawa, Risa Kuroshima
We present 4 square degree weak gravitational lensing survey of subhalos in the nearby Coma cluster using Subaru/Suprime-Cam. Thanks to large apparent size of cluster subhalos, we detected in a model-independent way 32 subhalos down to the order of 10^{-3} of the virial mass of the cluster. Weak-lensing mass measurement of shear-selected subhalos allows us to investigate subhalo properties and the correlation between subhalo masses and galaxy luminosities, for the first time. The mean distortion profiles stacked over subhalos show a sharply truncated feature which is well-fitted by Navarro Frenk & White (NFW) mass model with the truncation radius, as expected by the tidal destruction by the main cluster. We also found that subhalo masses, truncation radii and mass-to-light ratios decrease toward the cluster center. The subhalo mass function, dn/d \ln M_{sub}, in the range of two orders of magnitude in mass, is well described by a single power law or a Schechter function. Best-fit power indices of 1.11^{+0.45}_{-0.29} for the former model and 0.94_{-0.29}^{+0.46} for the latter one are in remarkable agreements with slopes of \sim0.9-1.0 predicted by the cold dark matter paradigm. The tangential distortion signals in the radial range of 0.02-2Mpc/h from the cluster center show a complex structure which is well described by a composition of three mass components of subhalos, NFW mass distribution as a smooth component of the main cluster, and lensing model from large scale structure behind the cluster. Although the lensing signals are one order lower than those for clusters at z\sim0.2, the total signal-to-noise ratio, S/N=13.3, is comparable to or higher because a large number of background source galaxies compensate low lensing efficiency of the nearby cluster.
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http://arxiv.org/abs/1304.2399
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