| A Composite Model for GHz Peaked Spectra of Radio Sources |
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| 作者姓名： | Jun Yang Xiang Liu and Zhi-Qiang Shen National Astronomical Observatories/Urumqi Observatory Chinese Academy of Sciences Urumqi Shanghai Astronomical Observatory Chinese Academy of Sciences Shanghai Graduate University of the Chinese Academy of Sciences Beijing |
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| 作者单位： | Jun Yang，Xiang Liu and Zhi-Qiang Shen National Astronomical Observatories/Urumqi Observatory，Chinese Academy of Sciences，Urumqi 830011; Shanghai Astronomical Observatory，Chinese Academy of Sciences，Shanghai 200030 Graduate University of the Chinese Academy of Sciences，Beijing 100049 |
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| 摘 要： | GHz-Peaked Spectrum (GPS) radio sources are powerful and compact sources with convex spectra. With increasing observational findings, it has been realized that either Synchrotron Self-Absorption (SSA) alone or Free-Free Absorption (FFA) alone is not enough to account for all the spectral features. We present a model consisting of an SSA region partially covered by FFA plasma, and derive a composite spectral formula. By applying the model to a sample of 19 GPS sources having strong absorption, it is found that the external FFA process makes the SSA peak frequency linearly shift to a higher (observed) peak frequency. The shift indicates that the FFA does play a role at the frequency close to the observed peak frequency.
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| 关 键 词： | 天体 连续谱 星系 恒星状球体 |
A Composite Model for GHz Peaked Spectra of Radio Sources |
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| Jun Yang,Xiang Liu and Zhi-Qiang Shen National Astronomical Observatories/Urumqi Observatory,Chinese Academy of Sciences,Urumqi , Shanghai Astronomical Observatory,Chinese Academy of Sciences,Shanghai Graduate University of the Chinese Academy of Sciences,Beijing .A Composite Model for GHz Peaked Spectra of Radio Sources[J].Chinese Journal of Astronomy and Astrophysics,2005,5(6):563-570. |
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| Authors: | Jun Yang Xiang Liu Zhi-Qiang Shen |
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| Institution: | [1]National Astronomical Observatories/Urumqi Observatory, Chinese Academy of Sciences, Urumqi 830011 [2]Shanghai Astronomical Observatory, Chinese Academy of Sciences, Shanghai 200030 [3]Graduate University of the Chinese Academy of Sciences, Beijing 100049 |
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| Abstract: | GHz-Peaked Spectrum (GPS) radio sources are powerful and compact sources with convex spectra. With increasing observational findings, it has been realized that either Synchrotron Self-Absorption (SSA) alone or Free-Free Absorption (FFA) alone is not enough to account for all the spectral features. We present a model consisting of an SSA region partially covered by FFA plasma, and derive a composite spectral formula. By applying the model to a sample of 19 GPS sources having strong absorption, it is found that the external FFA process makes the SSA peak frequency linearly shift to a higher (observed) peak frequency. The shift indicates that the FFA does play a role at the frequency close to the observed peak frequency. |
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| Keywords: | radio continuum: galaxies-galaxies: active -quasars: general |
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