模擬梅歇爾-87(Messier 87)中心快速旋轉黑洞之無線電噴流

Abstract

本研究由超大質量黑洞提供動力，探討從梅歇爾-87 (M87) 星系核心出現的大型無線電噴流呈現出對稱的臨邊增光效應 (limb-brightening)。藉由考慮中央黑洞的吸積盤與黑洞磁層配置，我們探討了相應的 VLBI 觀測特徵，包括圖像和光譜，亦改進了僅由相對論性電漿在連接至黑洞的大尺度磁場之無重力模型(Force-free model)。我們發現，M87 之噴流的對稱性臨邊增光效應 (symmetrical limb-brightening) 需要擁有一個快速旋轉的黑洞，與之前的研究結果相似。這種性質是因為電漿沿著噴流內大尺度磁場運動與為黑洞自旋函數的光柱 (light cylinder)的位置密切相關。我們亦證明了在噴流中具有非軸對稱質量負載 (mass loading) 的情況下，可以在距黑洞不同距離處改變 M87 噴流邊緣的較亮側。

Powered by a supermassive black hole, the large-scale radio jet emerging from the core of the Messier 87 (M87) galaxy exhibits a symmetric limb-brightened feature. Taking into account the accretion and black hole magnetosphere configurations of the central engine, we explore corresponding VLBI observational features, including images and spectra, with an improved force-free jet model which only consists of relativistic plasma motions along large-scale magnetic fields attached to the central black hole. It is found that the symmetric limb-brightening feature of the M87 jet requires a fast-spinning black hole, similar to previous studies. Such property is because the plasma motion along the large-scale magnetic field within the jet is closely related to the location of the light cylinder, which is a function of black hole spin. We also demonstrate that it is possible to vary the brighter side of the M87 jet limb at different distances from the black hole with non-axisymmetric mass loading in the jet.