The Kilo-Degree Survey ( KiDS ) is an optical wide-field survey designed to map the matter distribution in the Universe using weak gravitational lensing .
In this paper , we use these data to measure the density profiles and masses of a sample of \sim \mathrm { 1400 } spectroscopically identified galaxy groups and clusters from the Galaxy And Mass Assembly ( GAMA ) survey .
We detect a highly significant signal ( signal-to-noise-ratio \sim 120 ) , allowing us to study the properties of dark matter haloes over one and a half order of magnitude in mass , from M \sim 10 ^ { 13 } -10 ^ { 14.5 } h ^ { -1 } \mathrm { M _ { \sun } } .
We interpret the results for various subsamples of groups using a halo model framework which accounts for the mis-centring of the Brightest Cluster Galaxy ( used as the tracer of the group centre ) with respect to the centre of the group ’ s dark matter halo .
We find that the density profiles of the haloes are well described by an NFW profile with concentrations that agree with predictions from numerical simulations .
In addition , we constrain scaling relations between the mass and a number of observable group properties .
We find that the mass scales with the total r-band luminosity as a power-law with slope 1.16 \pm 0.13 ( 1-sigma ) and with the group velocity dispersion as a power-law with slope 1.89 \pm 0.27 ( 1-sigma ) .
Finally , we demonstrate the potential of weak lensing studies of groups to discriminate between models of baryonic feedback at group scales by comparing our results with the predictions from the Cosmo-OverWhelmingly Large Simulations ( Cosmo-OWLS ) project , ruling out models without AGN feedback .