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تسجيل مستخدم جديدCooling+Heating Flows in Galaxy clusters: Turbulent heating, spectral modelling, and cooling efficiency
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نشر من قبل
Mohammad Hossein Zhoolideh Haghighi
تاريخ النشر
2018
مجال البحث
فيزياء
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English
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The discrepancy between expected and observed cooling rates of X-ray emitting gas has led to the {it cooling flow problem} at the cores of clusters of galaxies. A variety of models have been proposed to model the observed X-ray spectra and resolve the cooling flow problem, which involves heating the cold gas through different mechanisms. As a result, realistic models of X-ray spectra of galaxy clusters need to involve both heating {it and} cooling mechanisms. In this paper, we argue that the heating time-scale is set by the magnetohydrodynamic (MHD) turbulent viscous heating for the Intracluster plasma, parametrised by the Shakura-Sunyaev viscosity parameter, $alpha$. Using a cooling+heating flow model, we show that a value of $alphasimeq 0.05$ (with 10% scatter) provides improved fits to the X-ray spectra of cooling flow, while at the same time, predicting reasonable cooling efficiency, $epsilon_{cool} = 0.33^{+0.63}_{-0.15}$. Our inferred values for $alpha$ based on X-ray spectra are also in line with direct measurements of turbulent pressure in simulations and observations of galaxy clusters. This simple picture unifies astrophysical accretion, as a balance of MHD turbulent heating and cooling, across more than 16 orders of magnitudes in scale, from neutron stars to galaxy clusters.
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