Discovery of a Cyclotron Resonance Feature in the X-Ray Spectrum of GX 304-1 with RXTE and Suzaku during Outbursts Detected by MAXI in 2010

作者：Yamamoto Takayuki^*; Sugizaki Mutsumi; Mihara Tatehiro; Nakajima Motoki; Yamaoka Kazutaka; Matsuoka Masaru; Morii Mikio; Makishima Kazuo

来源：Publications of the Astronomical Society of Japan, 2011, 63(sp3): S751-S757.

DOI：10.1093/pasj/63.sp3.s751

• pulsars: individual (GX 304-1)
• stars: magnetic fields
• stars: neutron
• X-rays: binaries

We report on the discovery of a cyclotron resonance scattering feature (CRSF) in the X-ray spectrum of GX 304-1, obtained by RXTE and Suzaku during major outbursts detected by MAXI in 2010. The peak intensity in August reached 600 mCrab in the 2-20 keV band, which is the highest ever observed from this source. The RXTE observations on more than twenty occasions and one Suzaku observation revealed a spectral absorption feature at around 54 keV, which is the first CRSF detection from this source. The estimated strength of the surface magnetic field, 4.7 x 10(12) G, is one of the highest among binary X-ray pulsars from which CRSFs have ever been detected. The RXTE spectra taken during the August outburst also suggest that the CRSF energy changed over 50-54 keV, possibly in a positive correlation with the X-ray flux. The behavior is qualitatively similar to that observed from Her X-I on long time scales, or from A 0535+26, but different from the negative correlation observed from 4U 0115+63 and X 0331+53.

• 出版日期2011