Uncovering substructure with wavelets:proof of concept using Abell 2744

Abstract

A recent comparison of the massive galaxy cluster Abell 2744 with the Millennium XXL (MXXL) N-body simulation has hinted at a tension between the observed substructure distribution and the predictions of ΛCDM. Follow-up investigations indicated that this could be due to the contribution from the host halo and the subhalo finding algorithm used. To be independent of any subhalo finding algorithm, we therefore investigate the particle data of the MXXL simulation directly. We propose a wavelet based method to detect substructures in 2D mass maps, which treats the simulation and observations equally. Using the same criteria to define a subhalo in observations and simulated data, we find three Abell 2744 analogues in the MXXL simulation. Thus the observations in Abell 2744 are in agreement with the predictions of ΛCDM. We investigate the reasons for the discrepancy between the results obtained from the SUBFIND and full particle data analyses. We find that this is due to incompatible substructure definitions in observations and SUBFIND.

The shape of relaxed galaxy clusters and the public release of a HST shape measurement code, pyRRG

“…As extreme peaks in the density field, clusters of galaxies are ideal laboratories to study dark matter (e.g. Harvey et al 2017b,a;Schwinn et al 2017Schwinn et al , 2018Kahlhoefer et al 2014;Robertson et al 2019) and constrain cosmology (e.g. Kratochvil et al 2010;Marian et al 2011;Cardone et al 2013).…”

Combining Faraday Tomography and Wavelet Analysis

“…In practice, the realization of the idea suggested in [9] is based on the wavelet technique. Wavelet functions are used for the analysis of spatial and temporal data, also in astrophysics [10]. The wavelet transform can be used as an enhancement of RM Synthesis to analyze structure at different scales [11,12].…”

Combining Faraday Tomography and Wavelet Analysis

“…Realization of the idea suggested in [7] is based on wavelet technique. Wavelet functions are used for an analysis of spatial and temporal data, also in astrophysics [8]. The wavelet transform can be used as an advance of RM-synthesis to structure analysis at different scales [9,10].…”