Preliminary results of the spectral analysis of Suzaku data of SW Ursae Majoris and BZ Ursae Majoris

•Thermal bremsstrahlung model fitted SW UMa and BZ UMa source spectrum.•Calculations yielded that the systems have mass accretion rates below 2 × 1016 gs−1.•We found the white dwarf radius of BZ UMa to be 6.88 × 108 cm.•Soft X-rays are originated from inner boundary layer or corona for SW UMa.•The analysis showed that the origin of X-rays must be boundary layer for BZ UMa.

Herein, we present the preliminary results of the spectral analysis of the Suzaku data of SW Ursae Majoris (SW UMa) and BZ Ursae Majoris (BZ UMa) which were obtained in their quiescent states. The aim of this study was to analyse 0.5–6.0 keV energy range X-ray photons of the Suzaku satellite and to determine their emission mechanisms and the areas where they were radiated from these two dwarf novae. No study on this energy range for BZ UMa has been reported in the literature. We analysed the Suzaku data in the (0.5–6.0) keV and in (0.5–2.5) keV energy bands of the systems separatelly to search for possible differences between the emission mechanisms in the energy ranges; however, none were found. We obtained the best-fitted spectral models, flux, luminosity, temperature and mass accretion rate values for the systems. The white dwarf radius of BZ UMa, which has not been reported in the literature, was found to be 6.88 × 108 cm. From this study, we concluded that the mass accretion rate values for both systems were lower than the critical mass accretion rate value in the boundary layers of cataclysmic variables, which indicates that the boundary layers are composed of optically thin thermal X-ray emitting gas in their quiescent state; these results support those of previous studies regarding SW UMa and some studies regarding BZ UMa. Another result was that there can be a coronal structure above the boundary layer which act as soft X-ray emitter for SW UMa.