Weak lensing analysis of galaxy pairs using CS82 data

ELIZABETH JOHANA GONZALEZ; FACUNDO RODRIGUEZ; DIEGO G. LAMBAS; MARTÍN MAKLER; VALERIA MESA; ALONSO, SOL; DUPLANCIC, FERNANDA

ASTRONOMY AND ASTROPHYSICS

EDP SCIENCES S A

Lugar: Paris; Año: 2019

0004-6361

Mass determinations of the halos of galaxy pairs are very important in order to understand galaxy evolution. Usually a dynamicalapproach is applied to derive the mass enclosed by the galaxies. However, determining these virial masses is very difficult given thatthe only available information are the velocity difference along the line-of-sight and the projected distance between the galaxies.On the other hand, weak lensing is an excellent technique for mass determinations at scales beyond the pair separation since it issensitive to both baryonic and non-baryonic content of the halo pair. In this work we analyze a sample of close galaxy pairs (relativeprojected separation < 25 h −1 kpc and relative radial velocities < 350 km s −1 ) using a weak lensing analysis based on the CFHTStripe 82 Survey. We determine halo masses for the Total sample of pairs as well as for Interacting, Red and Higher luminosity pairsubsamples. The derived lensing signal for the total sample can be fitted either with a singular isothermal sphere with σ V = 223 ± 24km s −1 or with a NFW profile with R 200 = 0.30 ± 0.03 h −1 Mpc. The pair total masses and total r band luminosities imply an averagemass-to-light ratio of ∼ 200 h M /L . On the other hand, Red pairs which include a larger fraction of elliptical galaxies, show a largermass-to-light ratio of ∼ 345 h M /L . Derived lensing masses were compared with halo masses obtained from the Yang et al. galaxygroup catalog, finding a very good agreement with the sample of groups with 2 members.