Lensing Magnification: A novel method to weigh high-redshift clusters and its application to SpARCS

Understand

We introduce a novel method to measure the masses of galaxy clusters at high redshift selected from optical and IR Spitzer data via the red-sequence technique.

• Lyman-break galaxies are used as a well understood, high-redshift background sample allowing mass measurements of lenses at unprecedented high redshifts using weak lensing magnification.
• By stacking a significant number of clusters at different redshifts with average masses of ~1-3x10^14M_sun, as estimated from their richness, we can calibrate the normalisation of the mass-richness relation.
• With the current data set (area: 6 deg^2) we detect a magnification signal at the >3-sigma level.