Constrained Simulation of the Bullet Cluster
Abstract
The Bullet Cluster collision is an ongoing collision of two galaxy clusters in the constellation of Carina. In this work, we have built a detailed simulation of this merger, including magnetohydrodynamics, plasma cooling, and adaptive mesh refinement. We constrain the simulation with data from gravitational lensing reconstructions and Chandra X-ray flux maps, then compare the resulting model to plasma temperature maps, Sunyaev-Zel'dovich effect measurements, and cluster halo radio emission. We constrain the initial conditions by minimizing the chi-squared figure of merit between the full 2D observational data sets and the simulation, rather than comparing only a few features such as the location of subcluster centroids, as in previous studies. A simple initial configuration of two triaxial clusters with Navarro-Frenk-White dark matter profiles and physically reasonable plasma profiles gives a good fit to the current observational morphology and X-ray emissions of the merging clusters. There is no need for unconventional physics or extreme infall velocities. The study gives insight into the astrophysical processes at play during a galaxy cluster merger. In addition, the techniques developed here to create realistic, stable, triaxial clusters, and to utilize the totality of the 2D image data, will be applicable to future simulation studies of other merging clusters. This work also highlights the important role of non-thermal pressure in galaxy clusters. A simple model of the non-thermal pressure is primarily used here, but we have investigated a more physical model where the non-thermal pressure is due to fluid turbulence, and have outlined a path for future work based on this more physical model.
- Publication:
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Ph.D. Thesis
- Pub Date:
- 2014
- Bibcode:
- 2014PhDT.......220L
- Keywords:
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- Physics, Astrophysics