Quantitative morphology of galaxy clusters at X-ray wavelengths

Hunt, Laura

Abstract

We apply quantitative morphology techniques to X-ray imaging of clusters of galaxies to determine correlation between calculated parameters (CAS, Gini and M20) and features such as bow shocks, cold fronts, gas sloshing, Kelvin-Helmholtz instabilities (KHI), X-ray cavities and relaxed/disturbed clusters. In order to do this we create a novel sample of 51 cluster images from archival data such as 𝐶ℎ𝑎𝑛𝑑𝑟𝑎 and 𝑋𝑀𝑀 − 𝑁𝑒𝑤𝑡𝑜𝑛 based on selection criteria spanning a redshift 0.01 < 𝑧 < 0.07 and X-ray luminosity 𝐿𝑥 > 1 × 1044 ergs s−1. We process the original images, and remove foreground sources and CCD gaps, and apply adaptive kernel smoothing on the central 3 Mpc of the clusters which is determined using an asymmetry technique to weight the luminosity centroid of the image. For each image we calculate the concentration of light C, the asymmetry index A, the clumpiness parameter S, the Gini coefficient G and the M20 parameter. We attempt to correlate these results with the physical features present and demonstrate that the presence of bow shocks is correlated with higher M20 and lower C and S, cavities correlate with low G and S, cold fronts show low S and G and higher M20, low S and high M20 correlate with gas sloshing and clusters that exhibit KHI have high S values.

Citation

Hunt, L. Quantitative morphology of galaxy clusters at X-ray wavelengths. (Thesis). University of Hull. https://hull-repository.worktribe.com/output/4224267

• Thesis Type: Thesis
• Deposit Date: Aug 2, 2022
• Publicly Available Date: Feb 24, 2023
• Keywords: Physics
• Public URL: https://hull-repository.worktribe.com/output/4224267
• Additional Information: Department of Physics and Mathematics, The University of Hull
• Award Date: Sep 1, 2021