Flexion based measures in galaxy clusters

In this work, I investigate the use of weak gravitational lensing signals as a measurement tool in galaxy cluster analysis. Intuitively, it is expected that the simpler shapes of early-type elliptical galaxies are better suited for gravitational lensing studies than late-type spiral galaxies; however, until now, no systematic study of the interplay has been conducted. I have undertaken an investigation of low and high redshift galaxy catalogs of known morphological type with a new gravitational lensing code, Lenser. Using color measurements in the u − r bands and fit S´ersic index values, objects with characteristics consistent with early-type galaxies are found to have a lower intrinsic scatter in flexion signal than late-type galaxies. The measured flexion noise can be characterized by morphology allowing for appropriate weighting within a lensing-based measurement or reconstruction, with early-type objects being lower by more than a factor of two in both low and high redshift regimes. I also perform a flexion based weak gravitational analysis of the first two Hubble Frontier Field clusters: Abell 2744 and MACS 0416. A parametric method for using projected flexion signals as a probe of cluster member mass is described in detail. The normalization, θ⋆E , and slope, ℓ, of a L − θE scaling relation is determined for each cluster using measured flexion signals, as a proxy for the L−σ Faber-Jackson relation. A parallel field analysis is undertaken simultaneously to provide a baseline measure of the method effectiveness, which returns an expected null measurement. I find an agreement in the Faber-Jackson power law exponent ℓ associated with galaxy age and morphology for both clusters, as well as theoretical distinction in the cluster normalization mass. For Abell 2744, we found a normalization mass of θ⋆E = 2.25 ± 0.46 and a slope value of ℓ = 0.62 ± 0.57. For MACS 0416, we found a normalization mass of θ⋆E = 4.55 ± 1.22 and a slope value of ℓ = 0.49 ± 0.15. A comparison with other studies directly verifies the measurement of the MACS 0416 cluster.