LIMB-BRIGHTENED JET OF 3C 84 REVEALED BY THE 43 GHz VERY-LONG-BASELINE-ARRAY OBSERVATION
LIMB-BRIGHTENED JET OF 3C 84 REVEALED BY THE 43 GHz VERY-LONG-BASELINE-ARRAY OBSERVATION
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DOI：
10.1088/0004-637x/785/1/53
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发表时间：
2014-02
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影响因子：
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通讯作者：
H. Nagai;Takafumi Haga;G. Giovannini;G. Giovannini;A. Doi;M. Orienti;M. Orienti;F. D’Ammando;M. Kino;M. Kino;M. Nakamura;K. Asada;K. Hada;K. Hada;M. Giroletti
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作者：
H. Nagai;Takafumi Haga;G. Giovannini;G. Giovannini;A. Doi;M. Orienti;M. Orienti;F. D’Ammando;M. Kino;M. Kino;M. Nakamura;K. Asada;K. Hada;K. Hada;M. Giroletti
我们基于43吉赫兹的甚长基线阵列数据，对射电星系3C 84/NGC 1275的亚秒差距尺度射电结构进行了研究。我们在与2005年射电爆发相关的“重新启动”的喷流中发现了边缘增亮现象。在20世纪90年代，尽管观测是在相似的角分辨率下进行的，但喷流结构是脊增亮而非边缘增亮。这表明横向喷流结构最近发生了变化。这种形态上的变化与γ射线流量的增加呈现出一种有趣的一致性，即20世纪90年代的γ射线流量至少比当前的低7倍。边缘增亮的一种合理的解释是，喷流的速度结构处于分层喷流的情境中，这是一种成功的情景，可以解释一些活动星系核中的γ射线发射。如果是这种情况，那么表观横向结构的变化可能是由横向速度结构的变化引起的。我们认为从脊增亮到边缘增亮的转变与几十年时间尺度上的γ射线时间可变性有关。我们还讨论了喷流的准直轮廓。
We present a study of the sub-parsec scale radio structure of the radio galaxy 3C 84/NGC 1275 based on the Very Long Baseline Array data at 43 GHz. We discover a limb brightening in the “restarted” jet that is associated with the 2005 radio outburst. In the 1990s, the jet structure was ridge brightening rather than limb brightening, despite the observations being done with similar angular resolutions. This indicates that the transverse jet structure has recently changed. This change in the morphology reveals an interesting agreement with the γ-ray flux increase, i.e., the γ-ray flux in the 1990s was at least seven times lower than the current one. One plausible explanation for the limb brightening is that the velocity structure of the jet is in the context of the stratified jet, which is a successful scenario that explains the γ-ray emission in some active galactic nuclei. If this is the case, then the change in apparent transverse structure might be caused by the change in the transverse velocity structure. We argue that the transition from ridge brightening to limb brightening is related to the γ-ray time variability on the timescale of decades. We also discuss the collimation profile of the jet.