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arXiv 0905.2815astro-ph.HE
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爆发中的超巨星快速X射线瞬变:XTEJ1739-302、IGRJ17544-2619和IGRJ08408-4503的新Swift观测

Supergiant Fast X-ray Transients in outburst: new Swift observations of XTEJ1739-302, IGRJ17544-2619, and IGRJ08408-4503

L. Sidoli, P. Romano, L. Ducci, A. Paizis, G. Cusumano, V. Mangano, H. A. Krimm, S. Vercellone, D. N. Burrows, J. A. Kennea, N. Gehrels

摘要:

我们报告了雨燕观测到的三个超巨星快X射线瞬变(SFXTs):XTEJ 1739 -302,IGRJ 17544 -2619和IGRJ 08408 -4503的新X射线爆发。前两次爆发是在我们自2007年10月以来一直使用Swift卫星进行的监测活动中捕获的:XTEJ 1739 -302在2008年8月13日经历了新的爆发,IGRJ 17544 -2619在2008年9月4日,而IGRJ 08408 -4503在2008年9月21日。虽然XTEJ 1739 -302和IGRJ 08408 -4503明亮的发射触发了雨燕/爆发警报望远镜,但IGRJ 17544 -2619没有,因此我们只能对低于10 keV的光谱进行光谱调查。XTEJ 1739 -302和IGRJ 08408 -4503的宽谱带光谱与以前耀斑期间显示的X射线光谱形状一致。在XTEJ 1739 -302中首次观测到耀斑期间的吸收柱密度变化。IGRJ 08408 -4503的宽带光谱需要两个不同的光子群,一个冷的(0.3 keV)最有可能来自中子星周围的热晕,另一个热的(1.4-1.8 keV)来自吸积柱。XTEJ 1739 -302的爆发可以用非常好的采样来监测,从而揭示了一种形状,这种形状可以用本SFXT中的第二个风分量来解释,类似于我们在周期性SFXT IGRJ 11215 -5952中提出的。在我们使用Swift进行的监测活动期间,IGRJ 17544 -2619中的爆发复发时间尺度表明轨道周期约为150天(在高度偏心的轨道上),与之前使用INTEGRAL观察到的一致。

英文摘要:

We report on new X-ray outbursts observed with Swift from three Supergiant Fast X-ray Transients (SFXTs): XTEJ1739-302, IGRJ17544-2619 and IGRJ08408-4503. The former two outbursts were caught during the monitoring campaign we have been performing with the Swift satellite since October 2007: XTEJ1739-302 underwent a new outburst on 2008, August 13, IGRJ17544-2619 on 2008, September 4, while IGRJ08408-4503 on 2008, September 21. While XTEJ1739-302 and IGRJ08408-4503 bright emission triggered the Swift/Burst Alert Telescope, IGRJ17544-2619 did not, thus we could perform a spectral investigation only of the spectrum below 10 keV. The broad band spectra from XTEJ1739-302 and IGRJ08408-4503 were compatible with the X-ray spectral shape displayed during the previous flares. A variable absorbing column density during the flare was observed in XTEJ1739-302 for the first time. The broad band spectrum of IGRJ08408-4503 requires the presence of two distinct photon populations, a cold one (0.3 keV) most likely from a thermal halo around the neutron star and a hotter one (1.4-1.8 keV) from the accreting column. The outburst from XTEJ1739-302 could be monitored with a very good sampling, thus revealing a shape which can be explained with a second wind component in this SFXT, in analogy to what we have suggested in the periodic SFXT IGRJ11215-5952. The outburst recurrence timescale in IGRJ17544-2619 during our monitoring campaign with Swift suggests a long orbital period of ~150 days (in an highly eccentric orbit), compatible with what previously observed with INTEGRAL.

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