The Nuclear Region of NGC 1068: High-Accuracy Alignment of the Optical and Radio Emission
The Nuclear Region of NGC 1068: High-Accuracy Alignment of the Optical and Radio Emission
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NGC 1068 的核区域：光学和无线电发射的高精度对准
DOI：
10.1086/310498
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发表时间：
1997
期刊：
影响因子：
--
通讯作者：
M. Lattanzi
中科院分区：
文献类型：
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作者：
A. Capetti;F. Macchetto;M. Lattanzi
我们提出了一个运动的结果，以获得准确的注册哈勃太空望远镜（HST）和MERLIN图像的NGC 1068，原型塞弗特2星系。最终配准精确到100 mas。揭示了无线电和光发射之间的强相互关系;特别是，无线电喷流位于相对低的光发射区域，并被线发射云包围。一个主要的例外是最亮的窄线区域（NLR）结，云B，它位于，至少在投影中，沿着无线电喷流。这些结果可以被理解为是由于喷流和周围介质之间的相互作用：在这种情况下，流出的等离子体正在清扫和加热星际气体。这种相互作用和压缩的结果是，无线电喷流沿沿着边缘的线发射被高度增强。因此，NGC 1068的NLR的形态似乎是由射电外流的存在所主导的，正如HST对几个塞弗特星系的射电辐射扩展观测所揭示的那样。在HST图像中观察到的光学峰位于α = 02 h 42 m 40. 711，δ = -00 ° 00 '47.″81（J2000，FK 5），误差为80 mas。用HST偏振成像仪测定的隐藏核的位置为α = 02 h 42 m 40.福尔斯710，δ = -00 ° 00 '48.“11（J2000，FK 5）。它向南偏移（即，沿着无线电轴）相对于两个最南端的无线电分量，特别是距反向频谱无线电分量S1 170 mas。这并不排除S1确实是无线电核心，但表明NGC 1068的核心可能是无线电静默的，或者它的辐射也吸收了无线电波长。有几个贡献的最终精度的光学到无线电登记。天体测量误差预算的显著减少必须等待实质性的改进，就像即将到来的HIPPARCOS目录中的无线电光学链路所预期的那样。
We present the results of a campaign to obtain an accurate registration of Hubble Space Telescope (HST) and MERLIN images of NGC 1068, the prototypical Seyfert 2 galaxy. The final registration is accurate to 100 mas. A strong anticorrelation between radio and optical emission is revealed; in particular, the radio jet lies on a region of relatively low optical emission and is surrounded by line-emitting clouds. A major exception is the brightest narrow-line region (NLR) knot, cloud B, which lies, at least in projection, along the radio jet. These results can be understood as due to the interaction between the jet and the surrounding medium: in this scenario, the outflowing plasma is sweeping and heating the interstellar gas. As a result of this interaction and compression, the line emission is highly enhanced along the edges of the radio jet. It therefore appears that the morphology of the NLR of NGC 1068 is dominated by the presence of a radio outflow, as already revealed by HST observations of several Seyfert galaxies with extended radio emission. The optical peak seen in the HST images is located at α = 02h42m40.ˢ711, δ = -00°00'47.″81 (J2000, FK5), with an error of 80 mas. The hidden nucleus, as determined by HST imaging polarimetry, falls at α = 02h42m40.ˢ710, δ = -00°00'48.″11 (J2000, FK5). It is offset toward the south (i.e., along the radio axis) with respect to the two southernmost radio components and, in particular, by 170 mas from the inverted spectrum radio component, S1. This does not rule out that S1 is indeed the radio core but suggests that the nucleus of NGC 1068 might be radio silent, or its emission absorbed at radio wavelengths also. There are several contributions to the final accuracy of the optical-to-radio registration. A significant decrease of the astrometric error budget has to wait for substantial improvements, like those expected from the radio-optical link in the forthcoming HIPPARCOS catalog.