The case for two-dimensional galaxy-galaxy lensing
  We revisit the performance and biases of the two-dimensional approach to
galaxy-galaxy lensing. This method exploits the information for the actual
positions and ellipticities of source galaxies, rather than using only the
ensemble properties of statistically equivalent samples. We compare the
performance of this method with the traditionally used one-dimensional
tangential shear signal on a set of mock data that resemble the current
state-of-the-art weak lensing surveys. We find that under idealised
circumstances the confidence regions of joint constraints for the amplitude and
scale parameters of the NFW model in the two-dimensional analysis can be more
than three times tighter than the one-dimensional results. Moreover, this
improvement depends on the lens number density and it is larger for higher
densities. We compare the method against the results from the hydrodynamical
EAGLE simulation in order to test for possible biases that might arise due to
lens galaxies being missed, and find that the method is able to return unbiased
estimates of halo masses when compared to the true properties of the EAGLE
galaxies. Because of its advantage in high galaxy density areas, the method is
especially suitable for studying the properties of satellite galaxies in
clusters of galaxies.
