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arXiv 1202.6084astro-ph.HE
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AGN环境中VHE Gamma-Ray诱导对级联的同步辐射

Synchrotron Emission from VHE Gamma-Ray Induced Pair Cascades in AGN Environments

Parisa Roustazadeh, Markus Boettcher

摘要:

从中低频尖峰耀变体中发现的甚高能量(VHE,E > 100 GeV)伽马射线辐射表明,这些天体中可能发生伽马-伽马吸收和对级联。在以前的论文中,我们研究了VHE γ射线诱导对级联的康普顿辐射,由中等磁场偏转,在很大程度上独立于模型的方式,并证明这种发射可以解释费米通量和光谱的射电星系Cen A和NGC 1275。在本文中,我们描述了我们的蒙特卡罗级联代码的泛化,包括从级联的角度依赖的同步输出,允许应用到不可忽略的磁场的情况下,导致潜在的可观察到的同步签名,但仍然没有主导级联粒子的辐射能量损失。我们证实了NGC 1275和Cen A级联的同步辐射对于我们以前工作中所用的参数是可以忽略的。我们证明,磁场不能确定从一个适合的级联发射的伽玛射线光谱单独,和简并只能解除,如果从级联的同步辐射也被观察到。我们用NGC 1275的例子来说明这个事实。我们指出,级联同步辐射可能在几个耀变体的光谱能量分布中产生与观测到的蓝色大凸起相同的能量范围内的光谱特征,并可能对这一特征作出不可忽略的贡献。我们用3C 279的例子来说明这个想法。

英文摘要:

The discovery of very-high-energy (VHE, E > 100 GeV) gamma-ray emission from intermediate- and low-frequency peaked blazars suggests that gamma-gamma absorption and pair cascading might occur in those objects. In previous papers, we investigated the Compton emission from VHE gamma-ray induced pair cascades, deflected by moderate magnetic fields, in a largely model-independent way, and demonstrated that this emission can explain the Fermi fluxes and spectra of the radio galaxies Cen A and NGC 1275. In this paper, we describe a generalization of our Monte-Carlo cascade code to include the angle-dependent synchrotron output from the cascades, allowing for the application to situations with non-negligible magnetic fields, leading to potentially observable synchrotron signatures, but still not dominating the radiative energy loss of cascade particles. We confirm that the synchrotron radiation from the cascades in NGC 1275 and Cen A are negligible for the parameters used in our previous works. We demonstrate that the magnetic field can not be determined from a fit of the cascade emission to the gamma-ray spectrum alone, and the degeneracy can only be lifted if the synchrotron emission from the cascades is observed as well. We illustrate this fact with the example of NGC 1275. We point out that the cascade synchrotron emission may produce spectral features in the same energy range in which the big blue bump is observed in the spectral energy distributions of several blazars, and may make a non-negligible contribution to this feature. We illustrate this idea with the example of 3C 279.

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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