We present the first scaling relation between weak-lensing galaxy cluster mass , M _ { WL } , and near-infrared luminosity , L _ { K } .
Our results are based on 17 clusters observed with wide-field instruments on Subaru , the United Kingdom Infrared Telescope , the Mayall Telescope , and the MMT .
We concentrate on the relation between projected 2D weak-lensing mass and spectroscopically confirmed luminosity within 1Mpc , modelled as M _ { WL } \propto L _ { K } ^ { b } , obtaining a power law slope of b = 0.83 ^ { +0.27 } _ { -0.24 } and an intrinsic scatter of \sigma _ { lnM _ { WL } |L _ { K } } = 10 ^ { +8 } _ { -5 } \% .
Intrinsic scatter of \sim 10 \% is a consistent feature of our results regardless of how we modify our approach to measuring the relationship between mass and light .
For example , deprojecting the mass and measuring both quantities within r _ { 500 } , that is itself obtained from the lensing analysis , yields \sigma _ { lnM _ { WL } |L _ { K } } = 10 ^ { +7 } _ { -5 } \% and b = 0.97 ^ { +0.17 } _ { -0.17 } .
We also find that selecting members based on their ( J - K ) colours instead of spectroscopic redshifts neither increases the scatter nor modifies the slope .
Overall our results indicate that near-infrared luminosity measured on scales comparable with r _ { 500 } ( typically 1Mpc for our sample ) is a low scatter and relatively inexpensive proxy for weak-lensing mass .
Near-infrared luminosity may therefore be a useful mass proxy for cluster cosmology experiments .