Weak lensing analysis of galaxy pairs using CS82 data
  In this work we analyze a sample of close galaxy pairs (relative projected
separation $<25 h^{-1}$kpc and relative radial velocities $< 350$ km s$^{-1}$)
using a weak lensing analysis based on the CFHT Stripe 82 Survey. We determine
halo masses for the Total sample of pairs as well as for Interacting, Red and
Higher luminosity pair subsamples with $\sim 3\sigma$ confidence. The derived
lensing signal for the total sample can be fitted either by a singular
isothermal sphere with $\sigma_V = 223 \pm 24$ km s$^{-1}$ or a NFW profile
with $R_{200} = 0.30 \pm 0.03\,h^{-1}$ Mpc. The pair total masses and total $r$
band luminosities imply an average mass-to-light ratio of $\sim
200\,h\,M_\odot/L_\odot$. On the other hand, Red pairs which include a larger
fraction of elliptical galaxies, show a larger mass-to-light ratio of $\sim
345\,h\,M_\odot/L_\odot$. Derived lensing masses were compared to a proxy of
the dynamical mass, obtaining a good correlation. However, there is a large
discrepancy between lensing masses and the dynamical mass estimates, which
could be accounted by astrophysical processes such as dynamical friction, by
the inclusion of unbound pairs, and by significant deviations of the density
distribution from a SIS and NFW profiles in the inner regions. We also compared
lensing masses with group mass estimates obtained from the Yang et al. galaxy
group catalog, finding a very good agreement with the sample of groups with 2
members. Red and Blue pairs show large differences between group and lensing
masses, which is likely due to the single mass-to-light ratio adopted to
compute the group masses.
