The HST survey of the B2 sample of radio-galaxies: Optical nuclei and the FR I/BL Lac unified scheme
The HST survey of the B2 sample of radio-galaxies: Optical nuclei and the FR I/BL Lac unified scheme
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DOI：
10.1051/0004-6361:20011714
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发表时间：
2001-12
影响因子：
6.5
通讯作者：
A. Capetti;A. Celotti;M. Chiaberge;H. D. Ruiter;R. Fanti;R. Morganti;P. P. O. A. D. Torino-P.;Italy Sissaisas;Trieste;Italy Space Telescope Science Institute;U. Bologna;I. Bologna;I. Bologna;Italy Netherlands Foundation for Research in Astronomy-Italy-Netherlands-Foundation-for-Research-in-2274401621
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作者：
A. Capetti;A. Celotti;M. Chiaberge;H. D. Ruiter;R. Fanti;R. Morganti;P. P. O. A. D. Torino-P.;Italy Sissaisas;Trieste;Italy Space Telescope Science Institute;U. Bologna;I. Bologna;I. Bologna;Italy Netherlands Foundation for Research in Astronomy-Italy-Netherlands-Foundation-for-Research-in-2274401621
我们使用B2样品的HST快照图像研究了低光度射电星系核的光学性质。与较亮的3C/FR I样品的分析结果一致，我们发现光学和射电核心的通量（和光度）之间存在相关性。这为FR I中的光学核发射主要由同步辐射控制以及这些源中的吸积发生在低效率辐射制度中的解释提供了进一步的支持。在FR I/BL拉克统一方案的框架下，我们发现FR I和BL Lac核之间的光度差异可以用一个在射电和光学波段都相同的聚束因子来再现，而与扩展射电光度无关，从而支持了这样的假设.相应的体洛伦兹因子明显小于从观测和理论考虑在BL拉克的预期：这可以解释为由于在射流的速度结构，与一个快速的脊柱包围一个较慢的层。
We examine the optical properties of the nuclei of low luminosity radio-galaxies using snapshot HST images of the B2 sample. In agreement with the results obtained from the analysis of the brighter 3C/FR I sample, we finda correlation between fluxes (and luminosities) of the optical and radio cores. This provides further support for the interpretation that the optical nuclear emission in FR I is dominated by synchrotron emission and that accretion in these sources takes place in a low efficiency radiative regime. In the framework of the FR I/BL Lacs unified scheme, we find that the luminosity difference between FR I and BL Lac nuclei can be reproduced with a common beaming factor in both the radio and the optical band, independent of the extended radio luminosity, thus supporting such a scenario. The corresponding bulk Lorentz factor is significantly smaller than is expected from observational and theoretical considerations in BL Lacs: this can be interpreted as due to a velocity structure in the jet, with a fast spine surrounded by a slower layer.