Astronomy Lunch Series
Mohammad Zhoolideh Haghighi
(IPM/PI/WCA)
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. 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 and cooling mechanisms. In this presentation, we argue that the heating time-scale is set by the MHD turbulent viscous heating for the intracluster plasma. In the first part of the talk, we introduce the cooling problem in the cluster of galaxies and X-ray spectral fitting. Then we are going to talk about heating mechanisms proposed to solve the cooling problem. In the second part, we introduce our model, Cooling+Heating flow model (CpH), and talk about fitting results of this model with X-ray observations. Using CpH flow model, we show that a value of α ≃ 0.08 (Shakura-Sunyaev viscosity parameter) provides improved fits to the X-ray spectra of cooling flow, while at the same time, predicting reasonable cold mass budgets accumulated in the cores of clusters over the Hubble time.