Accounting for object detection bias in weak gravitational lensing
  studies
  Weak lensing by large-scale structure is a powerful probe of cosmology if the
apparent alignments in the shapes of distant galaxies can be accurately
measured. Most studies have therefore focused on improving the fidelity of the
shape measurements themselves, but the preceding step of object detection has
been largely ignored. In this paper we study the impact of object detection for
a Euclid-like survey and show that it leads to biases that exceed requirements
for the next generation of cosmic shear surveys. In realistic scenarios,
blending of galaxies is an important source of detection bias. We find that
MetaDetection is able to account for blending, leading to average
multiplicative biases that meet requirements for Stage IV surveys, provided a
sufficiently accurate model for the point spread function is available. Further
work is needed to estimate the performance for actual surveys. Combined with
sufficiently realistic image simulations, this provides a viable way forward
towards accurate shear estimates for Stage IV surveys.
