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arXiv 0710.2847astro-ph
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放射性镓M87甚高能gamma-ray发射的同步辐射自康普顿方案

A synchrotron self-Compton scenario for the very high energy gamma-ray emission of the radiogalaxy M87

Jean-Philippe Lenain, Catherine Boisson, Hélène Sol, Krzysztof Katarzynski

摘要:

M87是第一个在TeV范围内发现的河外源,不是耀变体。随着地基切伦科夫望远镜性能的提高,我们现在可以在小的时间尺度上探测伽马射线通量的变化,从而对发射区的大小施加了很大的限制。TeV耀变体的标准排放模型的修改似乎有必要考虑到伽马射线观测,尽管这种错位。我们解释TeV的伽马射线光谱和快速变化的M87调用发射区靠近中央超大质量黑洞,这是充满了几个等离子体斑点的射流形成区的大开口角移动。我们发展了一个新的多斑点同步自康普顿(SSC)模型,在喷流中的阿尔芬表面之外的发射斑点,在距离中央发动机约100 r_g。该模型是明确适应处理大视角和中等值的洛伦兹因子推断(广义相对论)磁流体动力学模型的射流形成。这种情况可以解释高能立体系统(H.E.S.S.)最近对M87的伽马射线观测。望远镜阵列我们发现单个斑点半径约为10^{14} cm,这与H.E.S.S.最近报告的天数时间尺度的变化一致。协作,并且是黑洞引力半径的数量级。预测的非常高的能量发射的其他三个源与扩展的光学或X射线喷流,可能是错位耀变体仍然与中等光束的一个Seyfert 2射电星系,即Cen A,一个特殊的BL Lac,PKS 0521-36,和一个类星体,3C 273。

英文摘要:

M87 is the first extragalactic source detected in the TeV range that is not a blazar. With the increasing performances of ground-based Cherenkov telescopes, we can now probe the variability in the gamma-ray flux at small timescales, thus putting strong constraints on the size of the emitting zone. A modification of standard emission models of TeV blazars appears necessary to account for the gamma-ray observations despite this misalignment. We explain TeV gamma-ray spectra and fast variability of M87 by invoking an emission zone close to the central supermassive black hole, which is filled with several plasma blobs moving in the large opening angle of the jet formation zone. We develop a new multi-blob synchrotron self-Compton (SSC) model with emitting blobs beyond the Alfven surface in the jet, at a distance of about 100 r_g from the central engine. This model is explicitly adapted to deal with large viewing angles and moderate values of the Lorentz factor inferred from (general relativistic) magnetohydrodynamic models of jet formation. This scenario can account for the recent gamma-ray observations of M87 made by the High Energy Stereoscopic System (H.E.S.S.) telescope array. We find individual blob radii of about 10^{14} cm, which is compatible with the variability on timescales of days recently reported by the H.E.S.S. collaboration and is of the order of the black hole gravitational radius. Predictions of the very high energy emission for three other sources with extended optical or X-ray jet which could be misaligned blazars still with moderate beaming are presented for one Seyfert 2 radiogalaxy, namely Cen A, one peculiar BL Lac, PKS 0521-36, and one quasar, 3C 273.

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