Ep-Eiso Correlation in a Multiple Subjet Model of Gamma-Ray Bursts
Ep-Eiso Correlation in a Multiple Subjet Model of Gamma-Ray Bursts
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DOI：
10.1086/497388
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发表时间：
2005-04
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影响因子：
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通讯作者：
K. Toma;R. Yamazaki;Takashi Nakamura
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作者：
K. Toma;R. Yamazaki;Takashi Nakamura
我们进行蒙特卡洛模拟，以研究 γ 射线爆发 (GRB)、富含 X 射线的伽马暴 (XRR) 和 X 射线闪光 (XRF) 的多主体射流模型（或非均匀射流模型）背景下的 Ep-Eiso 相关性。对于单个主体，我们发现对于大视角，Ep ∝ E。对于所有主体具有相同内在属性的多主体射流模型，离轴事件显示 Ep ∝ E 且 0.4 < a < 0.5。如果主体射流的固有属性分布使得每个主体的轴上发射遵循相关性 Ep ∝ L，则我们在 Ep 中获得超过 3 个数量级的阿玛蒂相关性 (Ep ∝ E)。尽管模拟中阿马蒂相关周围的分散度很大，但结果与已知红移的GRB和由滞后光度相关推导出的伪红移的BASTE GRB的观测特性一致。我们还计算了HETE-2可以探测到的GRB、XRR和XRF的事件率、红移分布和T90持续时间分布，假设源红移分布与宇宙恒星形成速率成正比。研究发现，这三类的事件发生率相当，XRR 的平均红移略大于 GRB 和 XRF 的平均红移，并且当离轴观察单个主题或在轴上观察红移稍高时，会出现短 XRR。
We perform Monte Carlo simulations to study the Ep-Eiso correlation in the context of a multiple-subjet model (or inhomogeneous jet model) for γ-ray bursts (GRBs), X-ray-rich GRBs (XRRs), and X-ray flashes (XRFs). For a single subjet, we find that Ep ∝ E for large viewing angles. For the multiple-subjet model in which all the subjets have the same intrinsic properties, off-axis events show Ep ∝ E with 0.4 < a < 0.5. If the intrinsic properties of the subjets are distributed so that on-axis emission of each subjet follows a correlation Ep ∝ L, we obtain the Amati correlation (Ep ∝ E) over 3 orders of magnitude in Ep. Although the scatter around the Amati correlation is large in the simulation, the results are consistent with the observed properties of GRBs with known redshifts and the BASTE GRBs with pseudoredshifts derived from the lag-luminosity correlation. We also calculate the event rates, the redshift distributions, and the T90 duration distributions of GRBs, XRRs, and XRFs, which can be detected by HETE-2, assuming that the source redshift distribution is in proportion to the cosmic star formation rate. It is found that the event rates of the three classes are comparable, that the average redshift of the XRRs is a little larger than those of the GRBs and the XRFs, and that short XRRs arise when a single subjet is viewed off-axis or viewed on-axis with slightly high redshift.