Discovery of twin kilohertz quasi-periodic oscillations in the high Galactic latitude X-ray transient XTE J2123-058

被引:26
作者
Homan, J
Mendez, M
Wijnands, R
van der Klis, M
van Paradijs, J
机构
[1] Univ Amsterdam, Astron Inst Anton Pannekoek, NL-1098 SJ Amsterdam, Netherlands
[2] Ctr High Energy Astrophys, NL-1098 SJ Amsterdam, Netherlands
基金
美国国家航空航天局;
关键词
stars : individual (XTE J2123 -058); stars : neutron; X-rays : stars;
D O I
10.1086/311919
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
We report the discovery of twin kilohertz quasi-periodic oscillations (QPOs) in the persistent X-ray flux of the new X-ray transient XTE J2123-058. We detected the QPOs in data taken with the proportional counter array on board the Rossi X-Ray, Timing Explorer on 1998 July 14, when the source count rate was at about 50% of its outburst peak level. The frequencies of the QPOs were 853 +/- 4 and 1129 +/- 8 Hz, The peaks had widths of 32(-8)(+11) and 50(-13)(+18)Hz, and the rms amplitudes were 6.1(-0.6)(+0.7) % and 6.5(-0.8)(+0.9) %, respectively. The QPO frequencies increased marginally with count rate, and the amplitudes showed a small increase with photon energy. On the basis of the appearance in the color-color and hardness-intensity diagrams, the low-frequency power spectrum, and the strength of the kHz QPOs, the system can be classified as an atoll source. The source showed five type I X-ray bursts. The distance to the source is estimated to be about 10 (5-15) kpc, which combined with the high Galactic latitude of 36.degrees 2 indicates that the source is a located in the Galactic halo.
引用
收藏
页码:L119 / L122
页数:4
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