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arXiv 0804.4597astro-ph
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半人马座A及其核的毫米波连续谱

The millimeter-wave continuum spectrum of Centaurus A and its nucleus

F. P. Israel, D. Raban, R. S. Booth, F. T. Rantakyro

备注：
Astronomy and Astrophysics, in press
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摘要：

在FR-I活动星系核NGC 5128（半人马座A）射电发射机制的研究中，我们测定了整个半人马座A射电源的厘米和毫米连续谱，并在1989年至2005年期间的不同时间测量了活动星系核在86 GHz（3.5 mm）和345 GHz（0.85 mm）之间的连续辐射。积分Cen A谱在高于5GHz的频率处变得更陡，其中谱指数从-0.70变化到-0.82。半人马座A核心的毫米辐射是可变的，与20-200 keV的X射线变异性相比，与2 - 10 keV的X射线变异性的相关性要好得多。在静止状态下，核心光谱指数为-0.3，当核心变亮时，光谱指数变陡。的变化似乎主要与已在VLBI测量中检测到的内核喷流组件。致密的核成分在45-80 GHz以下是光学厚的。

英文摘要：

In a study of the radio emission mechanism of the FR-I AGN NGC 5128 (Centaurus A)}, we have determined the centimeter and millimeter continuum spectrum of the whole Centaurus A radio source and measured the continuum emission from the active galxy nucleus at various times between 1989 and 2005 at frequencies between 86 GHz (3.5 mm) and 345 GHz (0.85 mm). The integral Cen A spectrum becomes steeper at frequencies above 5 GHz, where the spectral index changes from -0.70 to -0.82. Millimeter emission from the core of Centaurus A is variable, and correlates appreciably better with the 20-200 keV than the 2 - 10 keV X-ray variability. In its quiescent state, the core spectral index is -0.3, which steepens when the core brightens. The variability appears to be mostly associated with the inner nuclear jet components that have been detected in VLBI measurements. The densest nuclear components are optically thick below 45-80 GHz.

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