A Composite Model for GHz Peaked Spectra of Radio Sources
A Composite Model for GHz Peaked Spectra of Radio Sources
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DOI：
10.1088/1009-9271/5/6/001
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发表时间：
2005-12
期刊：
影响因子：
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通讯作者：
Jun Yang;Xiang Liu;Zhi-qiang Shen
中科院分区：
文献类型：
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作者：
Jun Yang;Xiang Liu;Zhi-qiang Shen
GHz-Peak Spectrum(GPS)射电源是一种功率大、结构紧凑的凸谱射电源。随着越来越多的观测发现，人们已经意识到，仅有同步加速器自吸收(SSA)或自由自由吸收(FFA)都不足以解释所有的光谱特征。我们提出了一个由FFA等离子体部分覆盖的SSA区域组成的模型，并导出了合成光谱公式。将该模型应用于19个具有强吸收的GPS源的样本，发现外部FFA过程使SSA峰值频率线性地向更高的(观测)峰值频率移动。这一变化表明，FFA确实在接近观测峰值频率的频率处起作用。
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.