Weak lensing analysis of galaxy pairs using CS82 data

ELIZABETH J. GONZALEZ,; FACUNDO RODRIGUEZ ; DIEGO GARCÍA LAMBAS; MARTÍN MAKLER ; VALERIA MESA; ALONSO, SOL; FERNANDA DUPLANCIC; MARIA E. S. PEREIRA ; HUANYUAN SHAN

ASTRONOMY AND ASTROPHYSICS

EDP SCIENCES S A

Lugar: Paris; Año: 2019 vol. 621

0004-6361

In this work we analyze a sample of close galaxy pairs (relative projectedseparation <25h−1kpc and relative radial velocities <350 km s−1)using a weak lensing analysis based on the CFHT Stripe 82 Survey. We determinehalo masses for the Total sample of pairs as well as for Interacting, Red andHigher luminosity pair subsamples with ∼3σ confidence. The derivedlensing signal for the total sample can be fitted either by a singularisothermal sphere with σV=223±24 km s−1 or a NFW profilewith R200=0.30±0.03h−1 Mpc. The pair total masses and total rband luminosities imply an average mass-to-light ratio of ∼200hM⊙/L⊙. On the other hand, Red pairs which include a largerfraction of elliptical galaxies, show a larger mass-to-light ratio of ∼345hM⊙/L⊙. Derived lensing masses were compared to a proxy ofthe dynamical mass, obtaining a good correlation. However, there is a largediscrepancy between lensing masses and the dynamical mass estimates, whichcould be accounted by astrophysical processes such as dynamical friction, bythe inclusion of unbound pairs, and by significant deviations of the densitydistribution from a SIS and NFW profiles in the inner regions. We also comparedlensing masses with group mass estimates obtained from the Yang et al. galaxygroup catalog, finding a very good agreement with the sample of groups with 2members. Red and Blue pairs show large differences between group and lensingmasses, which is likely due to the single mass-to-light ratio adopted tocompute the group masses.