Stellar mass has been shown to correlate with halo mass , with non-negligible scatter .
The stellar mass-size and luminosity-size relationships of galaxies also show significant scatter in galaxy size at fixed stellar mass .
It is possible that , at fixed stellar mass and galaxy colour , the halo mass is correlated with galaxy size .
Galaxy-galaxy lensing allows us to measure the mean masses of dark matter haloes for stacked samples of galaxies .
We extend the analysis of the galaxies in the CFHTLenS catalogue by fitting single Sérsic surface brightness profiles to the lens galaxies in order to recover half-light radius values , allowing us to determine halo masses for lenses according to their size .
Comparing our halo masses and sizes to baselines for that stellar mass yields a differential measurement of the halo mass-galaxy size relationship at fixed stellar mass , defined as M _ { h } ( M _ { * } ) \propto r _ { \mathrm { eff } } ^ { \eta } ( M _ { * } ) .
We find that on average , our lens galaxies have an \eta = 0.42 \pm 0.12 , i.e .
larger galaxies live in more massive dark matter haloes .
The \eta is strongest for high mass luminous red galaxies ( LRGs ) .
Investigation of this relationship in hydrodynamical simulations suggests that , at a fixed M _ { * } , satellite galaxies have a larger \eta and greater scatter in the M _ { \mathrm { h } } and r _ { \mathrm { eff } } relationship compared to central galaxies .