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Can X-ray derived Pressure Maps Constrain Turbulence in the Intracluster Medium?

Published onJun 01, 2020
Can X-ray derived Pressure Maps Constrain Turbulence in the Intracluster Medium?

The intracluster medium (ICM), a diffuse plasma comprising of the vast majority of the baryons in the Universe, exists in a turbulent state in galaxy clusters. Quantifying to what degree turbulence affects the ICM is still underway. Direct observation of turbulence, via velocity measurements, evades current X-ray observatories. As such, the Kolmogorov power spectrum, a theory of turbulence where energy cascades from large scales to smaller scales following a scale dependent power law, provides a starting point. The power spectrum provides an estimate of the clusters’ turbulent state — the power law index. This study constrains the ICM turbulent Kolmogorov power indices for merging and relaxed clusters. Pressure maps are used as a proxy for energy density allowing us to estimate their Kolmogorov turbulent power spectrum index. The pressure maps used in this analysis are created by combining Chandra X-ray surface brightness images and X-ray temperature maps. The process to create these temperature and pressure maps was developed into a software pipeline, “ClusterPyXT”, and was recently published (Alden, et al., 2019, Astronomy and Computing 27, pg. 147). To better understand the results, synthetic pressure maps were created using the `TurbuStat’ code (Koch et al. 2019) to assess imposed biases caused by the map binning process. We discuss the results from this analysis and evaluate the viability of using current X-ray observations to measure the range of power spectrum indices for merging to relaxed clusters.

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