Suzaku Observation of the Intermediate Polar V1223 Sagittarii

Abstract

We report on the Suzaku observation of the intermediate polar V1223 Sagittarii. Using a multi-temperature plasma emission model with its reflection from a cold matter, we obtained the shock temperature to be 37.9^{+5.1}_{-4.6} keV. This constrains the mass and the radius of the white dwarf (WD) in the ranges 0.82^{+0.05}_{-0.06} solar masses and (6.9+/-0.4)x10^8 cm, respectively, with the aid of a WD mass-radius relation. The solid angle of the reflector viewed from the post-shock plasma was measured to be Omega/2pi = 0.91+/-0.26. A fluorescent iron Kalpha emission line is detected, whose central energy is discovered to be modulated with the WD rotation for the first time in magnetic-CVs. Detailed spectral analysis indicates that the line comprises of a stable 6.4 keV component and a red-shifted component, the latter of which appears only around the rotational intensity-minimum phase. The equivalent width (EW) of the former stable component ~80 eV together with the measured Omega indicates the major reflector is the WD surface, and the shock height is not more than 7% of the WD radius. Comparing this limitation to the height predicted by the Aizu model (1973), we estimated the fractional area onto which the accretion occurs to be < 7x10^{-3}$ of the WD radius, which is the most severe constraint in non-eclipsing IPs. The red-shifted iron line component, on the other hand, can be interpreted as emanating from the pre-shock accretion flow via fluorescence. Its EW (28^{+44}_{-13} eV) and the central energy (6.30_{-0.05}^{+0.07} keV) at the intensity-minimum phase are consistent with this interpretation.

25 pages, 13 figures, accepted for publication in PASJ (Suzaku & MAXI special issue)

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• An HST parallax of the distant cataclysmic variable V1223 Sgr, its system parameters, and accretion rate
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• X-ray reflection from cold white dwarfs in magnetic cataclysmic variables
• Measuring the masses of Intermediate Polars with NuSTAR: V709 Cas, NY Lup and V1223 Sgr
• The Magnetospheric Boundary in Cataclysmic Variables
• X-ray spectroscopy in the microcalorimeter era 4: Optical depth effects on the soft X-rays studied with CLOUDY
• IGR J18293-1213 is an eclipsing Cataclysmic Variable
• Application of a new X-ray reflection model to V1223 Sagittarii
• Breaking the degeneracy in magnetic cataclysmic variable X-ray spectral modeling using X-ray light curves
• Classifying IGR J15038-6021 as a magnetic CV with a massive white dwarf
• Significant reflection and absorption effects in the X-ray emission of the Intermediate Polar IGR J17195-4100