Estimate of halo ellipticity as a function of radius with flexions

Abstract

The cold dark matter theory predicts triaxial dark matter haloes. The radial distribution of halo ellipticity depends on baryonic processes and the nature of dark matter particles (collisionless or collisional). Here we show that we can use lensing flexion ratios to measure the halo ellipticity as a function of radius. We introduce a weight function and study the relationship between the first and second order statistics of flexion ratios, both of which can be used to reduce the bias in the estimate of ellipticity. we perform numerical tests for our method, and demonstrate that it can reduce the bias and determine the halo ellipticity as a function of radius. We also point out that the minimum mean flexion ratio can be used to trace the centres of galaxy clusters.

9 pages,9 figures, MNRAS accepted

References in corpus (18)

• A direct empirical proof of the existence of dark matter
• Cosmology with Weak Lensing Surveys
• Revealing the properties of dark matter in the merging cluster MACSJ0025.4-1222
• The Causes of Halo Shape Changes Induced by Cooling Baryons: Disks Versus Substructures
• The Halos of Satellite Galaxies: the Companion of the Massive Elliptical Lens SL2S J08544-0121
• The shapes, orientation, and alignment of Galactic dark matter subhalos
• The Dependence of the Mass Assembly History of Cold Dark Matter Halos on Environment
• A New Look at Massive Clusters: weak lensing constraints on the triaxial dark matter halos of Abell 1689, Abell 1835, & Abell 2204
• Alignment between galaxies and large-scale structure
• Probing the Intrinsic Shape and Alignment of Dark Matter Haloes using SDSS Galaxy Groups
• Weak lensing goes bananas: What flexion really measures
• Weak gravitational shear and flexion with polar shapelets
• A Method for Weak Lensing Flexion Analysis by the HOLICs Moment Approach
• Measuring the Three-Dimensional Structure of Galaxy Clusters. II. Are clusters of galaxies oblate or prolate?
• Probing Galaxy Dark Matter Haloes in COSMOS with Weak Lensing Flexion
• Measuring Gravitational Lensing Flexions in Abell 1689 Using an Analytic Image Model
• Detecting Mass Substructure in Galaxy Clusters: An Aperture Mass Statistic for Gravitational Flexion
• Estimate of dark halo ellipticity by lensing flexion

Cited by in corpus (5)

• Halo Shapes From Weak Lensing: The Impact of Galaxy--Halo Misalignment
• Constraints on the shapes of galaxy dark matter haloes from weak gravitational lensing
• Analytical shear and flexion of Einasto dark matter haloes
• Measurement of halo properties with weak lensing shear and flexion
• Estimation of halo ellipticity using spin-3 flexion