Heating and acceleration of intracluster medium protons by turbulence

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Abstract/Contents

Abstract: We investigate the possibility of nonthermal inverse bremsstrahlung radiation as a source of hard X-ray emissions from the intracluster medium of galaxy clusters. In particular, using a numerical algorithm that simultaneously solves the coupled Fokker-Planck equations of protons and electrons subject to Coulomb collisions and stochastic acceleration, we determine whether it is possible to accelerate background protons without excessive heating. Under a simplified but generic acceleration model adopted in Petrosian & East (2008), the time evolution of both proton and electron spectra are computed. We find that nonthermal protons necessary for the inverse bremsstrahlung process to produce hard X-ray photons can emerge only with excessive heating of the entire plasma, unless the acceleration parameters, the duration of the acceleration, and/or the initial distributions are significantly fine-tuned. These results severely constraint the feasibility of nonthermal inverse bremsstrahlung process producing hard X-ray emissions. In Appendix A, we also derive and present a formula for the energy loss rate by the proton-proton interaction, which becomes the dominant energy loss process for protons of kinetic energy higher than 320 MeV.

Type of resource	text
Date created	2012

Author	Kang, Byungwoo
Degree granting institution	Stanford University, Department of Physics
Primary advisor	Petrosian, Vahe
Advisor	Madejski, Grzegorz (Greg)

Related item	Title 2012 Firestone Medal for Excellence in Undergraduate Research
Location	https://purl.stanford.edu/tb469hy3847

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License: This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).

Preferred Citation: Kang, Byungwoo (2012). Heating and acceleration of intracluster medium protons by turbulence. Stanford Digital Repository. Available at http://purl.stanford.edu/tb469hy3847.

Undergraduate Theses, Department of Physics

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