Stochastic particle acceleration and the problem of background plasma overheating

Please use this identifier to cite or link to this item: https://ir.lib.ncu.edu.tw/handle/987654321/100897

Title:	Stochastic particle acceleration and the problem of background plasma overheating
Authors:	高仲明;Chernyshov, D. O.;Dogiel, V. A.;Ko, C. M.
Contributors:	理學院天文研究所
Keywords:	ACCELERATION;ASTROPHYSICS;ASTROPHYSICS, COSMOLOGY AND ASTRONOMY;BREMSSTRAHLUNG;Constants;COSMIC ELECTRONS;ELECTRON EMISSION;ELECTRON TEMPERATURE;Emission;Emittance;GALAXY CLUSTERS;GAMMA ASTRONOMY;HARD X RADIATION;ION TEMPERATURE;Mathematical models;Particle acceleration;PHOTON EMISSION;PLASMA;PLASMA HEATING;STOCHASTIC PROCESSES;Stochasticity;X-RAY GALAXIES
Date:	2012-11-10
Issue Date:	2026-04-21 14:17:45 (UTC+8)
Publisher:	IOP Publishing Ltd.;United States
Abstract:	摘要： The origin of hard X-ray (HXR) excess emission from clusters of galaxies is still an enigma, whose nature is debated. One of the possible mechanisms to produce this emission is the bremsstrahlung model. However, previous analytical and numerical calculations showed that in this case the intracluster plasma had to be overheated very fast because suprathermal electrons emitting the HXR excess lose their energy mainly by Coulomb losses, i.e., they heat the background plasma. It was concluded also from these investigations that it is problematic to produce emitting electrons from a background plasma by stochastic (Fermi) acceleration because the energy supplied by external sources in the form of Fermi acceleration is quickly absorbed by the background plasma. In other words, the Fermi acceleration is ineffective for particle acceleration. We revisited this problem and found that at some parameter of acceleration the rate of plasma heating is rather low and the acceleration tails of nonthermal particles can be generated and exist for a long time while the plasma temperature is almost constant. We showed also that for some regime of acceleration the plasma cools down instead of being heated up, even though external sources (in the form of external acceleration) supply energy to the system. The reason is that the acceleration withdraws effectively high-energy particles from the thermal pool (analog of Maxwell demon). 出版者： United States 出版日期： 2012-11-10 出處： The Astrophysical journal, 2012-11, Vol.759 (2), p.113-11 資源來源： Institute of Physics Journals 識別號： ISSN: 0004-637X 識別號： ISSN: 1538-4357 識別號： EISSN: 1538-4357 識別號： DOI: 10.1088/0004-637X/759/2/113
Appears in Collections:	[Graduate Institute of Astronomy] journal & Dissertation

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