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arXiv 1407.0155astro-ph.HE
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对伽马射线暴强子含量的限制

Constraints on The Hadronic Content of Gamma Ray Bursts

Lee Yacobi, Dafne Guetta, Ehud Behar

摘要:

IceCube高能中微子望远镜自2006年以来一直在收集数据。相反,自2008年发射以来,费米号上的GBM已经探测到数百个伽马射线暴(GRB)。到目前为止,还没有中微子事件与GRB有关,尽管许多模型预测通过GRB光子与GRB喷流中PeV质子的相互作用产生高能中微子。我们使用中微子的非检测约束强子的GRB喷注的内容独立的喷注模型参数。假设$E^{-α}$与$α= 2$的一般粒子谱,我们发现在95%的置信水平下,π介子携带的能量与电子携带的能量之比必须是小的$f_π/ f_e \lesssim 0.24$.光谱斜率的分布可以将$f_π/ f_e$降低几个数量级。另一个限制,独立的中微子,得到如果一个归因于测量费米/LAT GeV的伽马射线发射的高能光子对光子级联产生的(相同的光子强子相互作用和随后的)中性π衰变。根据观测到的$\approx 10$的MeV与GeV的GRB注量比,我们证明了$f_π/ f_e \lesssim 0.3$ .在某些脉冲串中,该比率低至1,即$f_π/ f_e \lesssim 0.03$。这些发现增加了对伽玛射线暴喷流中PeV质子存在的越来越多的怀疑。

英文摘要:

The IceCube high-energy neutrino telescope has been collecting data since 2006. Conversely, hundreds of Gamma Ray Bursts (GRBs) have been detected by the GBM on board Fermi, since its launch in 2008. So far no neutrino event has been associated with a GRB, despite many models predicting the generation of high energy neutrinos through GRB photon interaction with PeV protons in the GRB jet. We use the non-detection of neutrinos to constrain the hadronic content of GRB jets independent of jet model parameters. Assuming a generic particle spectrum of $E^{-α}$ with $α= 2$, we find that the ratio of the energy carried by pions to that in electrons has to be small $f_π/ f_e \lesssim 0.24$ at 95\% confidence level. A distribution of spectral slopes can lower $f_π/ f_e$ by orders of magnitude. Another limit, independent of neutrinos, is obtained if one ascribes the measured Fermi/LAT GeV gamma-ray emission to pair-photon cascades of high-energy photons resulting from (the same photon-hadronic interactions and subsequent) neutral pion decays. Based on the generally observed MeV to GeV GRB fluence ratio of $\approx 10$, we show that $f_π/ f_e \lesssim 0.3$. In some bursts, where this ratio is as low as unity, $f_π/ f_e \lesssim 0.03$. These findings add to the mounting doubts regarding the presence of PeV protons in GRB jets.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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