INDICATION OF THE BLACK HOLE POWERED JET IN M87 BY VSOP OBSERVATIONS
INDICATION OF THE BLACK HOLE POWERED JET IN M87 BY VSOP OBSERVATIONS
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DOI：
10.3847/1538-4357/833/1/56
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发表时间：
2016-12-10
影响因子：
4.9
通讯作者：
Pu, Hung-Yi
中科院分区：
文献类型：
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作者：
Asada, Keiichi;Nakamura, Masanori;Pu, Hung-Yi
为了研究相对论喷流的准直和加速机制，利用1.6GHz和5GHz的VSOP观测图像，对M87的毫角秒尺度喷流流线进行了广泛的研究。由于VSOP具有较高的角分辨率，特别是在射流的横向，我们将射流流线分解为三条毫角秒尺度的脊线。虽然外两条脊线的性质与先前观测中测量的结果非常一致，并且可以用一条幂律指数为1.7的幂律线表示，但首次清楚地观察到了内脊线。我们比较了测量的大小与Blandford和Znajek的抛物解，这是锚定在事件视界，不同的黑洞自旋参数预期的最外层流线。我们发现，观测到的内脊线比预测的要窄，这表明内脊线的起源是源自旋转黑洞的脊柱的一部分。在5 GHz下，内脊线在距离中央引擎很远的地方变得非常暗淡。我们考虑了两种可能的情况：多普勒波束和/或辐射冷却。这两种情况似乎都可以合理解释，未来的多频率观测将区分这两种可能性。
In order to study the collimation and acceleration mechanism of relativistic jets, the jet streamline of M87 at milliarcsecond scale is extensively investigated with images from VSOP observations at 1.6 and 5 GHz. Thanks to the higher angular resolution of VSOP, especially in the direction transverse to the jet, we resolved the jet streamline into three ridgelines at the scale of milli arcseconds. While the properties of the outer two ridgelines are in good agreement with those measured in previous observations and can be expressed by one power-law line with a power law index of 1.7, an inner ridgeline is clearly observed for the first time. We compared the measured size with the outermost streamline expected by Blandford & Znajek's parabolic solutions, which are anchored at the event horizon, with different black hole spin parameters. We revealed that the observed inner ridgeline is narrower than the prediction, suggesting the origin of the inner ridgeline to be part of a spine originating from the spinning black hole. The inner ridgeline becomes very dim at large distances from the central engine at 5 GHz. We considered two possible cases for this; Doppler beaming and/or radiative cooling. Either case seems to be reasonable for its explanation, and future multi-frequency observations will discriminate those two possibilities.