Marcello Cacciato - May 21, 2015

Properties of GAMA galaxies from a lensing analysis of the KiDS survey

Galaxy-galaxy lensing is a statistical probe of the mass distribution
around galaxies. In turn, it allows for a detailed scrutiny of the
galaxy-dark matter connection. We measure the tangential shear
distortion around spectroscopically selected galaxies from the GAMA
survey using background galaxy shapes extracted from the spatially
overlapping regions of the deeper, higher imaging quality KiDS survey.
Armed with a highly flexible halo model, we interpret the measured
signal for various subsamples of galaxies. We establish the relation 
between galaxy stellar mass and halo mass with high significance and 
up to redshift of about 0.4. We characterise the mass density profiles 
of the haloes that host those galaxies. We infer the total mass of 
aggregations of galaxies, such as groups or clusters, and we put
constraints on the average separation between BCGs and the centre
of their groups. Finally, we  directly probe the matter associated to satellite
galaxies in a statistical manner. As the statistical power of
galaxy-galaxy lensing will drastically increase in the near future
(see e.g. DES, full-KiDS, HSC, Euclid), we envision that all these
measurements will become a standard test for galaxy formation models.