期刊
ASTRONOMY & ASTROPHYSICS
卷 520, 期 -, 页码 -出版社
EDP SCIENCES S A
DOI: 10.1051/0004-6361/201014542
关键词
accretion, accretion disks; novae, cataclysmic variables; X-rays: binaries
资金
- Japan Society for the Promotion of Science
- Grants-in-Aid for Scientific Research [22340046] Funding Source: KAKEN
Context. White dwarfs (WDs) in cataclysmic variables (CVs) are important experimental laboratories where the electron degeneracy is taking place on a macroscopic scale. Magnetic CVs increase in number especially in the hard X-ray band (greater than or similar to 10 keV) thanks to sensitive hard X-ray missions. Aims. From X-ray spectroscopy, we estimate the masses of nearby WDs in moderately-magnetized CVs, or Intermediate Polars (IPs). Methods. Using the Suzaku satellite, we aquired wide-band spectra of 17 IPs, covering 3-50 keV. An accretion column model of Suleimanov et al. (2005, A&A, 435, 191) and an optically-thin thermal emission code were used to construct a spectral emission model of IPs with resolved Fe emission lines. By simultaneously fitting the Fe line complex and the hard X-ray continuum of individual spectra, the shock temperature and the WD mass were determined with a better accuracy than in previous studies. Results. We determined the WD masses of the 17 IPs with statistical fitting errors of less than or similar to 0.1-0.2 M-circle dot in many cases. The WD mass of a recently-found IP, IGR J17195-4100, was also estimated for the first time (1.03(-0.22)(+0.24) M-circle dot). The average WD mass of the sample is 0.88 +/- 0.25 M-circle dot. When our results were compared with previous X-ray mass determinations, we found significant deviation in a few systems although the reason of this is unclear. The iron abundance of the accreting gas was also estimated, and confirmed the previously reported sub-solar tendency in all sources with better accuracy.
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