Close galaxy pairs with accurate photometric redshifts
  Context. Studies of galaxy pairs can provide valuable information to jointly
understand the formation and evolution of galaxies and galaxy groups.
Consequently, taking into account the new high precision photo-z surveys, it is
important to have reliable and tested methods that allow us to properly
identify these systems and estimate their total masses and other properties.
Aims. In view of the forthcoming Physics of the Accelerating Universe Survey
(PAUS) we propose and evaluate the performance of an identification algorithm
of projected close isolated galaxy pairs. We expect that the photometric
selected systems can adequately reproduce the observational properties and the
inferred lensing mass - luminosity relation of a pair of truly bound galaxies
that are hosted by the same dark matter halo. Methods. We develop an
identification algorithm that considers the projected distance between the
galaxies, the projected velocity difference and an isolation criteria in order
to restrict the sample to isolated systems. We apply our identification
algorithm using a mock galaxy catalog that mimics the features of PAUS. To
evaluate the feasibility of our pair finder, we compare the identified
photometric samples with a test sample that considers that both members are
included in the same halo. Also, taking advantage of the lensing properties
provided by the mock catalog, we apply a weak lensing analysis to determine the
mass of the selected systems. Results. Photometric selected samples tend to
show high purity values, but tend to misidentify truly bounded pairs as the
photometric redshift errors increase. Nevertheless, overall properties such as
the luminosity and mass distributions are successfully reproduced. We also
accurately reproduce the lensing mass - luminosity relation as expected for
galaxy pairs located in the same halo.
