Weak Lensing Study in VOICE Survey II: Shear Bias Calibrations
  The VST Optical Imaging of the CDFS and ES1 Fields (VOICE) Survey is proposed
to obtain deep optical $ugri$ imaging of the CDFS and ES1 fields using the VLT
Survey Telescope (VST). At present, the observations for the CDFS field have
been completed, and comprise in total about 4.9 deg$^2$ down to
$r_\mathrm{AB}$$\sim$26 mag. In the companion paper by Fu et al. (2018), we
present the weak lensing shear measurements for $r$-band images with seeing
$\le$ 0.9 arcsec. In this paper, we perform image simulations to calibrate
possible biases of the measured shear signals. Statistically, the properties of
the simulated point spread function (PSF) and galaxies show good agreements
with those of observations. The multiplicative bias is calibrated to reach an
accuracy of $\sim$3.0%. We study the bias sensitivities to the undetected faint
galaxies and to the neighboring galaxies. We find that undetected galaxies
contribute to the multiplicative bias at the level of $\sim$0.3%. Further
analysis shows that galaxies with lower signal-to-noise ratio (SNR) are
impacted more significantly because the undetected galaxies skew the background
noise distribution. For the neighboring galaxies, we find that although most
have been rejected in the shape measurement procedure, about one third of them
still remain in the final shear sample. They show a larger ellipticity
dispersion and contribute to $\sim$0.2% of the multiplicative bias. Such a bias
can be removed by further eliminating these neighboring galaxies. But the
effective number density of the galaxies can be reduced considerably. Therefore
efficient methods should be developed for future weak lensing deep surveys.
