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arXiv 1502.02383astro-ph.HE
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来自3c454.3的恒星-喷流相互作用和Gamma-Ray爆发

Star-Jet Interactions and Gamma-Ray Outbursts from 3c454.3

M. V. Barkov, D. V. Khangulyan, V. Bosch-Ramon, F. A. Aharonian, A. V. Dorodnitsyn

摘要:

我们提出了一个模型来解释超明亮的GeV伽玛射线耀斑观测到的耀变体\c 454。该模型是基于一个相对论性喷流的概念,当一颗恒星(红巨星)穿过靠近中央黑洞的喷流时,喷流与致密气体凝聚相互作用。这项研究包括分析处理喷流内恒星失去的包层的演变,以及计算相关的高能辐射。该模型很容易解释为期一天的,可变的时间尺度上的小时,GeV的伽马射线耀斑从\c 454,在2010年11月期间观察到的长达数周的平台。在提出的方案中,高原状态是由在喷星相互作用区域加速的非热粒子加热恒星大气产生的强风引起的。耀斑本身可能是由红巨星在喷流最初撞击后失去的一些物质云产生的。在所提出的设想的框架内,观测约束了源的关键模型参数,包括中心黑洞的质量:$M_{\rm BH}\simeq 10^9 M_{\odot}$,总喷流功率:$L_{\rm j}\simeq 10^{48}\,\rm erg\,s^{-1}$,以及伽马射线发射云的多普勒因子,$δ\simeq 20$。虽然我们没有指定的粒子加速机制,潜在的伽马射线的生产过程进行了讨论和比较的背景下,所提出的模型。我们认为质子的同步辐射与直接加速电子的其他辐射通道相比具有一定的优势。

英文摘要:

We propose a model to explain the ultra-bright GeV gamma-ray flares observed from the blazar \c454. The model is based on the concept of a relativistic jet interacting with compact gas condensations produced when a star (red giant) crosses the jet close to the central black hole. The study includes an analytical treatment of the evolution of the envelop lost by the star within the jet, and calculations of the related high-energy radiation. The model readily explains the day-long, variable on timescales of hours, GeV gamma-ray flare from \c454, observed during November 2010 on top of a weeks-long plateau. In the proposed scenario, the plateau state is caused by a strong wind generated by the heating of the star atmosphere by nonthermal particles accelerated at the jet-star interaction region. The flare itself could be produced by a few clouds of matter lost by the red giant after the initial impact of the jet. In the framework of the proposed scenario, the observations constrain the key model parameters of the source, including the mass of the central black hole: $M_{\rm BH}\simeq 10^9 M_{\odot}$, the total jet power: $L_{\rm j}\simeq 10^{48}\,\rm erg\,s^{-1}$, and the Doppler factor of the gamma-ray emitting clouds, $δ\simeq 20$. Whereas we do not specify the particle acceleration mechanisms, the potential gamma-ray production processes are discussed and compared in the context of the proposed model. We argue that synchrotron radiation of protons has certain advantages compared to other radiation channels of directly accelerated electrons.

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