A KiDS weak lensing analysis of assembly bias in GAMA galaxy groups
  We investigate possible signatures of halo assembly bias for
spectroscopically selected galaxy groups from the GAMA survey using weak
lensing measurements from the spatially overlapping regions of the deeper,
high-imaging-quality photometric KiDS survey. We use GAMA groups with an
apparent richness larger than 4 to identify samples with comparable mean host
halo masses but with a different radial distribution of satellite galaxies,
which is a proxy for the formation time of the haloes. We measure the weak
lensing signal for groups with a steeper than average and with a shallower than
average satellite distribution and find no sign of halo assembly bias, with the
bias ratio of $0.85^{+0.37}_{-0.25}$, which is consistent with the $\Lambda$CDM
prediction. Our galaxy groups have typical masses of $10^{13} M_{\odot}/h$,
naturally complementing previous studies of halo assembly bias on galaxy
cluster scales.
