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arXiv 0704.3438astro-ph
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伽马射线暴谱中的黑体成分

Black-body components in Gamma-Ray Bursts spectra?

G. Ghirlanda, Z. Bosnjak, G. Ghisellini, F. Tavecchio, C. Firmani

备注：
14 pages, 13 figures, accepted for publication in MNRAS
发表信息：
Mon.Not.Roy.Astron.Soc.379:73-85,2007
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摘要：

我们研究了7个伽马射线暴（GRB），它们都是由康普顿伽玛射线天文台的BATSE仪器和BeppoSAX卫星的宽视场照相机（WFC）探测到的。这些爆发具有测量的光谱红移，并且是定义峰值能量E_peak（即vFv光谱的峰值）和总的瞬发各向同性能量E_iso（所谓的“Amati”关系）之间的相关性的爆发的相当大的部分。最近的理论解释这种相关性假设，黑体辐射占主导地位的时间分辨光谱的伽玛暴，即使在时间积分谱，它的存在可能被隐藏的变化，其温度和稀释的一个可能的非热幂律成分。我们进行了时间分辨光谱分析，并表明，幂律和黑体的总和提供了可接受的适合的BATSE能量范围内的时间相关的光谱，但overpredicts的通量在WFC的X射线范围。此外，与截止幂律加上黑体的拟合是一致的WFC数据，但黑体分量的贡献可以忽略不计的总通量的一部分。相反，我们发现，拟合光谱与带模型或一个简单的截止幂律模型产生的X射线通量和光谱斜率，以及匹配的WFC光谱。

英文摘要：

We study 7 Gamma Ray Bursts (GRBs), detected both by the BATSE instrument, on-board the Compton Gamma Ray Observatory, and by the Wide Field Camera (WFC), on-board BeppoSAX. These bursts have measured spectroscopic redshifts and are a sizeable fraction of the bursts defining the correlation between the peak energy E_peak (i.e. the peak of the vFv spectrum) and the total prompt isotropic energy E_iso (the so called "Amati" relation). Recent theoretical interpretations of this correlation assume that black-body emission dominates the time resolved spectra of GRBs, even if, in the time integrated spectrum, its presence may be hidden by the change of its temperature and by the dilution of a possible non-thermal power law component. We perform a time resolved spectral analysis, and show that the sum of a power-law and a black-body gives acceptable fits to the time dependent spectra within the BATSE energy range, but overpredicts the flux in the WFC X-ray range. Moreover, a fit with a cutoff power-law plus a black-body is consistent with the WFC data, but the black-body component contributes a negligible fraction of the total flux. On the contrary, we find that fitting the spectra with a Band model or a simple cutoff power-law model yields an X-ray flux and spectral slope which well matches the WFC spectra.

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