Weak Lensing Analysis of A2390 Using Short Exposures

Abstract

We present a weak lensing analysis of the galaxy cluster A2390 at z = 0.23 using second moment shape measurements made in 411 short 60 s exposures. The exposures are obtained in three broadband photometric filters ( g , r , and i ) using WIYN-ODI. Shape measurement in individual exposures is done using a moment-matching algorithm. Forced measurement is used when the moment-matching algorithm fails to converge at low signal-to-noise ratio. The measurements made in individual images are combined using inverse error weighting to obtain accurate shapes for the sources and hence recover shear. We use PhoSim simulations to validate the shear measurements recovered by our pipeline. We find the mass of A2390 is in agreement with previously published results. We also find the E-mode maps show filamentary structures consistent with baryonic structures and recover most clusters/groups of galaxies found using optical and X-ray data. Thus, we demonstrate the feasibility of using weak lensing to map large-scale structure of the Universe. We also find the central portion of the cluster has a bimodal mass distribution and the relative orientation of the peaks is similar to X-ray. We discuss earlier research on this galaxy cluster, and show that a late-stage merger accounts for all the observed data.

Keywords

• Weak gravitational lensing
• Galaxy clusters