Noisy weak-lensing convergence peak statistics near clusters of galaxies
  and beyond
  Taking into account noise from intrinsic ellipticities of source galaxies, in
this paper, we study the peak statistics in weak-lensing convergence maps
around clusters of galaxies and beyond. We emphasize how the noise peak
statistics is affected by the density distribution of nearby clusters, and also
how cluster-peak signals are changed by the existence of noise. These are the
important aspects to be understood thoroughly in weak-lensing analyses for
individual clusters as well as in cosmological applications of weak-lensing
cluster statistics. We adopt Gaussian smoothing with the smoothing scale
$\theta_G=0.5\hbox{ arcmin}$ in our analyses. It is found that the noise peak
distribution near a cluster of galaxies depends sensitively on the density
profile of the cluster. For a cored isothermal cluster with the core radius
$R_c$, the inner region with $R\le R_c$ appears noisy containing on average
$\sim 2.4$ peaks with $\nu\ge 5$ for $R_c= 1.7\hbox{ arcmin}$ and the true peak
height of the cluster $\nu=5.6$, where $\nu$ denotes the convergence signal to
noise ratio. For a NFW cluster of the same mass and the same central $\nu$, the
average number of peaks with $\nu\ge 5$ within $R\le R_c$ is $\sim 1.6$. Thus a
high peak corresponding to the main cluster can be identified more cleanly in
the NFW case. In the outer region with $R_c<R\le 5R_c$, the number of high
noise peaks is considerably enhanced in comparison with that of the pure noise
case without the nearby cluster. (abridged)
