Application of the new comprehensive X-ray spectral model to the two brightest intermediate polars ex hydrae and V1223 sagittarii

Abstract

We applied the new comprehensive X-ray spectral model for the post-shock accretion column (PSAC) of the intermediate polars (IPs) constructed by Hayashi and Ishida to the Suzaku data of the two brightest IPs EX Hydrae and V1223 Sagittarii. The white dwarf (WD) mass and the specific accretion rate of EX Hya are estimated to be MWD = 0.63+0.17-0.14 M⊙ and a = 0.049+0.66-0.035 g cm-2 s-1. Our WD mass of EX Hya is greater than that of previous X-ray estimations (~0.4-0.5M⊙), where higher specific accretion rate than ours is assumed, and marginally consistent with 0.790±0.026M⊙ measured by Beuermann and Reinsch using a binary motion. On the other hand, with the aid of the PSAC height of V1223 Sgr hV1223 < 0.07RWD, we estimated MWD = 0.87+0.10-0.06 M⊙ and a > 2.0 g cm-2 s-1 for V1223 Sgr. We evaluated the fractional accreting area of EX Hya and V1223 Sgr at 0.0033+0.0067-0.0030 and <0.007, respectively. Calculation of the hydrodynamical equations with these best-fitting parameters show that the PSAC height of EX Hya is 0.33 RWD =2.8×108 cm. The maximum temperature of the EX Hya and V1223 Sgr are calculated at 18.0 keV and 43.1 keV, respectively. In EX Hya, the temperature distribution is flatter and the density at the top of the PSAC is smaller than those of the previous PSAC models because of its low specific accretion rate. © 2014 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society.