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arXiv 1102.0851astro-ph.HE
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类星体和微类星体的强子束模型

On hadronic beam models for quasars and microquasars

Diego F. Torres, Anita Reimer

摘要:

文献中发现的类星体(QSO)和微类星体(MQ)的强子喷流模型大多代表粒子束(例如质子)。这些粒子与系统中伴星的恒星风中的物质相互作用,或者与穿越的云相互作用,通过质子-质子过程产生伽马射线。我们的目标是推导出观测者所看到的喷流中的粒子分布,以便正确计算$γ$射线和中微子的产额。我们使用相对论不变量,以获得转换后的表达式的情况下的幂律和幂律与截止粒子分布的光束。我们与以前的表达在文献中使用。我们表明,以前使用的表达式的粒子分布在光束中所看到的观察者是错误的,差异强烈依赖于视角。例如,对于$Γ=10$($Γ$是团块的洛伦兹因子)和大于$\sim 20^o$的角度,早期使用的计算需要对$E>Γmc^2$的质子谱进行过度预测(数量级或更多),而它总是过度预测(两个数量级)较低能量的质子谱,而不考虑视角。所有的结果,光子和中微子通量的强子模型中的光束,利用早期的计算受到影响。考虑到与已发表的结果相比,正确的伽马射线通量几乎在任何情况下都将显著减少,并且在切伦科夫设施中的观测时间随着通量减少因子的平方而增长,在统计上有限的结果中,观测强子束的可能性被破坏。

英文摘要:

Most of the hadronic jet models for quasars (QSOs) and microquasars (MQs) found in literature represent beams of particles (e.g. protons). These particles interact with the matter in the stellar wind of the companion star in the system or with crossing clouds, generating gamma-rays via proton-proton processes. Our aim is to derive the particle distribution in the jet as seen by the observer, so that proper computation of the $γ$-ray and neutrino yields can be done. We use relativistic invariants to obtain the transformed expressions in the case of a power-law and power-law with a cutoff particle distribution in the beam. We compare with previous expressions used earlier in the literature. We show that formerly used expressions for the particle distributions in the beam as seen by the observer are in error, differences being strongly dependent on the viewing angle. For example, for $Γ=10$ ($Γ$ is the Lorentz factor of the blob) and angles larger than $\sim 20^o$, the earlier-used calculation entails an over-prediction (order of magnitude or more) of the proton spectra for $E>Γmc^2$, whereas it always over-predicts (two orders of magnitude) the proton spectrum at lower energies, disregarding the viewing angle. All the results for photon and neutrino fluxes in hadronic models in beams that have made use of the earlier calculation are affected. Given that correct gamma-ray fluxes will be in almost any case significantly diminished in comparison with published results, and that the time of observations in Cherenkov facilities grows with the square of the flux-reduction factor in a statistically limited result, the possibility of observing hadronic beams is undermined.

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