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arXiv 0908.0733astro-ph.HEastro-ph.CO
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GRB超新星GRB 031203和XRF 060218可能是宇宙孪生吗?

Could the GRB-Supernovae GRB 031203 and XRF 060218 be Cosmic Twins?

Lu Feng, Derek B. Fox

摘要:

由INTEGRAL发现的伽马射线暴(GRB)/X射线闪光(XRF)事件GRB 031203和由Swift发现的XRF 060218是仅有的五个GRB-SNe中的两个,它们的SN成分得到了光谱学的确认。然而,它们观察到的高能特性提供了鲜明的对比:GRB 031203被检测为一个40秒的短爆发,光谱峰值在E_peak > 190 keV,XRF 060218是一个T_90 ~ 2100秒长,平滑演变的爆发,峰值能量E_peak = 4.9 keV。与此同时,在对GRB 031203的快速响应XMM-牛顿观测中观察到的两个扩展的尘埃散射X射线晕的性质表明,该事件伴随着“X射线爆炸”,其通量与瞬发伽马射线事件相当或更大。以这一观测结果为出发点,我们通过对XMM数据的详细建模,研究了GRB 031203 X射线爆炸的可能性质,发现了第三个晕,这是由于在d_3 = 9.94 +/- 0.39 kpc处散射了一个更遥远的尘埃层,以及将X射线爆炸相对于GRB触发时间的定时限制为t_0 = 11 +/-417秒。使用我们的约束条件,我们比较GRB 031203的属性与其他GRB-SNe的属性,以了解其X射线爆炸的可能性质,得出的结论是明亮的X射线耀斑,如GRB 050502 B,或冲击爆发事件,如XRF 060218,提供了最可能的解释。在后一种情况下,我们考虑了另一种可能性,即XRF 060218可能在雨燕观测到的爆发之前出现了一段明亮的伽马射线发射,在这种情况下,GRB 031203和XRF 060218将是具有几乎相同的高能特性的“宇宙孪生”爆炸。

英文摘要:

The gamma-ray burst (GRB) / X-ray flash (XRF) events GRB 031203, discovered by INTEGRAL, and XRF 060218, discovered by Swift, represent two of only five GRB-SNe with optical spectroscopic confirmation of their SN components. Yet their observed high-energy properties offer a sharp contrast: While GRB 031203 was detected as a short 40-s burst with a spectrum peaking at E_peak > 190 keV, XRF 060218 was a T_90 ~ 2100-s long, smoothly-evolving burst with peak energy E_peak = 4.9 keV. At the same time, the properties of the two expanding dust-scattered X-ray halos observed in a fast-response XMM-Newton observation of GRB 031203 reveal that this event was accompanied by an "X-ray blast" with fluence comparable to or greater than that of the prompt gamma-ray event. Taking this observation as our starting point, we investigate the likely properties of the X-ray blast from GRB 031203 via detailed modeling of the XMM data, discovering a third halo due to scattering off a more distant dust sheet at d_3 = 9.94 +/- 0.39 kpc, and constraining the timing of the X-ray blast relative to the GRB trigger time to be t_0 = 11 +/- 417 s. Using our constraints, we compare the properties of GRB 031203 to those of other GRB-SNe in order to understand the likely nature of its X-ray blast, concluding that a bright X-ray flare, as in GRB 050502B, or shock breakout event, as in XRF 060218, provide the most likely explanations. In the latter case, we consider the added possibility that XRF 060218 may have manifested an episode of bright gamma-ray emission prior to the burst observed by Swift, in which case GRB 031203 and XRF 060218 would be "cosmic twin" explosions with nearly identical high-energy properties.

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