Vol 22, No 4

A Study on White Dwarf Masses in Cataclysmic Variables Based on XMM-Newton and Suzaku Observations

Zhuo-Li Yu, Xiao-Jie Xu, Xiang-Dong Li


Abstract The distribution of the mass of white dwarfs (WDs) is one of the fundamental questions in the field of cataclysmic variables (CVs). In this work, we make a systematical investigation on the WD masses in two subclass of CVs: intermediate polars (IPs) and non-magnetic CVs in the solar vicinity based on the flux ratios of Fe XXVI–Lyα to Fe XXV–Heα emission lines (I7.0/I6.7) from archival XMM-Newton and Suzaku observations. We first verify the (semi-empirical) relations between I7.0/I6.7, the maximum emission temperature (Tmax) and the WD mass (MWD) with the mkcflow model based on the apec description and the latest AtomDB. We then introduce a new spectral model to measure MWD directly based on the above relations. A comparison shows that the derived MWD is consistent with dynamically measured ones. Finally, we obtain the average WD masses of 58 CVs (including 36 IPs and 22 non-magnetic CVs), which is the largest X-ray selected sample. The average WD masses are \(\langle M_{\rm WD, IP}\rangle = 0.81 \pm 0.21 M_{\odot}\) and \(M_{\rm WD,DN}= 0.81\pm 0.21M_{\odot}\) for IPs and non-magnetic CVs, respectively. These results are consistent with previous works.


Keywords : (stars:) binaries (including multiple): close – (stars:) novae – cataclysmic variables – X-rays: binaries

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