Cooling + Heating flow in galaxy clusters: Turbulent heating, spectral modelling and cold mass budget

محّمد حسین ژولیده حقیقی

 (دانشکده فیزیک دانشگاه صنعتی شریف – پژوهشکده نجوم پژوهشگاه دانش های بنیادی IPM)

Abstract :  The discrepancy between expected and observed cooling rates of X-ray emitting gas has led to the cooling flow problem at the cores of clusters of galaxies. To fit X-ray spectra and solve cooling flow problem, a variety of models have been proposed that involve heating the cold gas through different mechanisms. As a result, realistic models of  X-ray spectra of galaxy clusters need to involve both heating 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, in terms of the Shakura-Sunyaev viscosity parameter α. Using this cooling+heating flow model, we show that values of α = 0.05 − 0.13 provide improved fits to the X-ray spectra of cooling flows, while at the same time, predicting reasonable cold mass budgets accumulated in the cores of clusters over a Hubble time.     Our inferred values for α based on X-ray spectra, are also in line with direct measurements of turbulent pressure in simulations and observations of galaxy clusters.

یکشنبه 30 اردیبهشت 1397، ساعت 15:00

دانشکده فیزیک، طبقه اول کلاس فیزیک 3