Weak lensing constraints on galaxy halos

Abstract

Weak gravitational lensing has become an important tool to study the properties of dark matter halos around galaxies, thanksto the advent of large panoramic cameras on 4 m class telescopes. Thisarea of research has been developing rapidly in the past few years,and in these proceedings we present some results based on theRed-Sequence Cluster Survey, thus highlighting what can be achieved withcurrent data sets. We present results on the measurement of virial masses as afunction of luminosity and the extent of dark matter halos. Muchlarger surveys are underway or planned, which will result in animpressive improvement in the accuracy of the measurements. However,the interpretation of future results will rely more and more oncomparison with numerical simulations, thus providing direct tests ofgalaxy formation models.