Detailed cluster lensing profiles at large radii and the impact on
  cluster weak lensing studies
  Using a large set of ray-tracing in N-body simulations, we examine lensing
profiles around massive dark haloes in detail, with a particular emphasis on
the profile at around the virial radii. We compare radial convergence profiles,
which are measured accurately in the ray-tracing simulations by stacking many
dark haloes, with our simple analytic model predictions. Our analytic models
consist of a main halo, which is modelled by the Navarro-Frenk-White (NFW)
density profile with three different forms of the truncation, plus the
correlated matter (2-halo term) around the main halo. We find that the smoothly
truncated NFW profile best reproduces the simulated lensing profiles, out to
more than 10 times the virial radius. We then use this analytic model to
investigate potential biases in cluster weak lensing studies in which a single,
untruncated NFW component is usually assumed in interpreting observed signals.
We find that cluster masses, inferred by fitting reduced tangential shear
profiles with the NFW profile, tend to be underestimated by ~5-10% if fitting
is performed out to ~10'-30'. In contrast, the concentration parameter is
overestimated typically by ~20% for the same fitting range. We also investigate
biases in computing the signal-to-noise ratio of weak lensing mass peaks,
finding them to be <4% for significant mass peaks. In the Appendices, we
provide useful formulae for the smoothly truncated NFW profile.
