Statistical uncertainties and systematic errors in weak lensing mass
  estimates of galaxy clusters
  Upcoming and ongoing large area weak lensing surveys will also discover large
samples of galaxy clusters. Accurate and precise masses of galaxy clusters are
of major importance for cosmology, for example, in establishing well calibrated
observational halo mass functions for comparison with cosmological predictions.
We investigate the level of statistical uncertainties and sources of systematic
errors expected for weak lensing mass estimates. Future surveys that will cover
large areas on the sky, such as Euclid or LSST and to lesser extent DES, will
provide the largest weak lensing cluster samples with the lowest level of
statistical noise regarding ensembles of galaxy clusters. However, the expected
low level of statistical uncertainties requires us to scrutinize various
sources of systematic errors. In particular, we investigate the bias due to
cluster member galaxies which are erroneously treated as background source
galaxies due to wrongly assigned photometric redshifts. We find that this
effect is significant when referring to stacks of galaxy clusters. Finally, we
study the bias due to miscentring, i.e., the displacement between any
observationally defined cluster centre and the true minimum of its
gravitational potential. The impact of this bias might be significant with
respect to the statistical uncertainties. However, complementary future
missions such as eROSITA will allow us to define stringent priors on
miscentring parameters which will mitigate this bias significantly.
