Suzaku X-Ray Spectroscopy of a Peculiar Hot Star in the Galactic Center Region

Abstract

We present the results of a Suzaku study of a bright point-like source in the 6.7keV intensity map of the Galactic center region. We detected an intense FeXXV 6.7keV line with an equivalent width of ∼1keV as well as emission lines of highly ionized Ar and Ca from a spectrum obtained by the X-ray Imaging Spectrometer. The overall spectrum is described very well by a heavily absorbed (∼2×10²³ cm^-2) thin thermal plasma model with a temperature of 3.8±0.6keV and a luminosity of ∼3×10³⁴ ergs^-1 (2.0--8.0keV) at 8kpc. The absorption, temperature, luminosity, and the 6.7keV line intensity were confirmed with the archived XMM-Newton data. The source has a very red (J-K_s = 8.2mag) infrared spectral energy distribution (SED), which was fitted by a blackbody emission of ∼1000K attenuated by a visual extinction of ∼31mag. The high plasma temperature and the large X-ray luminosity are consistent with a wind-wind colliding Wolf-Rayet binary. The similarity of the SED to those of the eponymous Quintuplet cluster members suggests that the source is a WC-type source.