利用贝叶斯分层模型估算耀变体的多普勒因子

Estimation of the Doppler Factors for Blazars Using a Bayesian Hierarchical Model

基于亚毫米波阵列(Submillimeter Array,SMA)的1 mm波长的长时间监测数据,利用贝叶斯分层模型对耀变体的光变曲线进行拟合,估算了155个耀变体的射电亮温度和光变多普勒因子。利用Wilcoxon秩和检验,比较了蝎虎座BL型天体(BL Lac)子样本和平谱射电类星体(Flat Spectrum Radio Quasar,FSRQ)子样本的亮温度和多普勒因子分布,也比较了费米耀变体和非费米耀变体的亮温度和多普勒因子分布。结果表明:(1)相对蝎虎座BL型天体,平谱射电类星体平均具有更高的多普勒因子;(2)相对非费米耀变体,费米耀变体平均具有更高的亮温度和多普勒因子。通过与15 GHz波段的亮温度和多普勒因子进行比较发现,射电亮温度和多普勒因子可能有向更高频率降低的趋势。

Based on the long-term monitoring data at 1 mm wavelength from the Submillimeter Array(SMA),we used a Bayesian hierarchical model to fit the light curves of 155 blazars and estimated their radio brightness temperatures and variability Doppler factors.The brightness temperature and Doppler factor distributions between BL Lacertae objects(BL Lacs)and flat spectrum radio quasars(FSRQs),as well as between Fermi and non-Fermi blazars,were compared using the Wilcoxon rank-sum test.The results show that(1)FSRQs have higher average Doppler factor than BL Lacs;(2)Fermi blazars have higher average brightness temperature and Doppler factor than non-Fermi blazars.After comparing the brightness temperatures and variability Doppler factors at 1 mm and 15 GHz wavelengths,we found a tendency of decreasing towards higher frequencies for these two parameters.