Pinpoint the jet apex in 3C 84
Pinpoint the jet apex in 3C 84
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DOI：
10.22323/1.399.0043
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发表时间：
2021-10
期刊：
影响因子：
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通讯作者：
G. Paraschos;Jae-Young Kim;T. Krichbaum;J. Oh;J. Hodgson;M. Gurwell;J. Zensus
中科院分区：
文献类型：
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作者：
G. Paraschos;Jae-Young Kim;T. Krichbaum;J. Oh;J. Hodgson;M. Gurwell;J. Zensus
由活动星系核提供动力的喷流是研究其中心黑洞（BH）及其周围环境的关键因素。这类喷流的形成是一个深入研究的课题，主要基于两种主要的喷流发射方案所提出的二分法--一种来自Blandford&Payne（1982），另一种来自Blandford&Znajek（1977）。在这项工作中，我们研究了突出的和附近的射电星系3C 84（NGC 1275）与15，43，和86 GHz的准同步VLBI观测。从这些，我们确定射流顶点位于86 GHz VLBI核心的上游83\pm7\，\mu $as（0.028 -0.11$pc），应用二维互相关分析。该分析的副产品是光谱指数图，其中我们首次以如此高的分辨率为43-86 GHz对识别出南北方向上稳健的光谱指数梯度。在VLBI核心的磁场强度与其他突出的活动星系核（如NGC 1052和M 87）的文献测量值（史瓦西半径）相当，计算值为70 - 600 G。磁场拓扑的影响进行了讨论。
Jets which are powered by an AGN are a crucial element in the study of their central black holes (BH) and their immediate surroundings. The formation of such jets is the subject of intense research, mainly based on the dichotomy presented by the two main jet launching scenarios $-$ the one from Blandford&Payne (1982), and the one from Blandford&Znajek (1977). In this work we study the prominent and nearby radio galaxy 3C 84 (NGC 1275) with 15, 43, and 86 GHz quasi-simultaneous VLBI observations. From these we determine the jet apex to be located $83\pm7\,\mu$as ($0.028-0.11$pc) upstream of the 86 GHz VLBI core, applying a two dimensional cross-correlation analysis. A byproduct of this analysis are spectral index maps, in which we identify a robust spectral index gradient in the north-south direction, for the first time at such high resolution, for the 43-86 GHz pair. The magnetic field strength at distances from the VLBI core comparable to measurements from the literature ($\sim10$ Schwarzschild radii) for other prominent AGN, like NGC 1052 and M 87, is computed to be $70-600$G. Implications for the magnetic field topology are also discussed.