The origin of ultra high energy cosmic rays (UHECRs) is still an open question in astroparticle physics. TeV blazars are a small group of active galactic nuclei (AGNs). They all have been observed in TeV gamma ray ban...The origin of ultra high energy cosmic rays (UHECRs) is still an open question in astroparticle physics. TeV blazars are a small group of active galactic nuclei (AGNs). They all have been observed in TeV gamma ray band, and show violent variabilities in flux at all wavelengths. So it is believed that they have abilities to produce UHECRs. To judge whether the TeV blazars can be the candidates of the origin of UHECRs, we collect the information of emission region of 38 TeV blazars, and estimate the maximum energy that the charged particle can be accelerated there. The results show that TeV blazars have abilities to accelerate cosmic rays to the energy above 1018?eV, some even higher than 1020?eV, and they may be the sources of UHECRs.展开更多
The multiband nonthermal emissions in radio, X-ray, and very high-energy（VHE） γ-ray bands from two distant blazars, H 2356–309 and 1ES 1218＋304, havebeen detected, and, especially from recent observations with th...The multiband nonthermal emissions in radio, X-ray, and very high-energy（VHE） γ-ray bands from two distant blazars, H 2356–309 and 1ES 1218＋304, havebeen detected, and, especially from recent observations with the Suzaku, MAGICand VERITAS telescopes, clearly reveal nonthermal power-law spectra. We study thebroadband nonthermal spectra of the two sources by using a combination of a one-zone homogeneous synchrotron self-Compton （SSC） model and an inhomogeneousconical jet model, where the new external background light （EBL） model is taken intoaccount. The results show that （1） the nonthermal emissions of the two blazars, rang-ing from X-rays to VHE γ-rays, are from the homogeneous zone whereas the emis-sions in the radio bands can be explained as the radiation from the inhomogeneousconical jet; （2） a strict lower-limit EBL model can be used to explain their observedspectra well.展开更多
利用支持向量机(Support Vector Machine,SVM)、随机森林(Random Forest,RF)、集成学习(Ensemble Learning,EM)和多层感知机(Multi-Layer Perceptron,MLP)将罗马5期耀变体多波段目录(The 5th edition of the Roma-BZCAT Multifrequency ...利用支持向量机(Support Vector Machine,SVM)、随机森林(Random Forest,RF)、集成学习(Ensemble Learning,EM)和多层感知机(Multi-Layer Perceptron,MLP)将罗马5期耀变体多波段目录(The 5th edition of the Roma-BZCAT Multifrequency Catalogue of Blazars,5BZCAT)中227个不确定类型的耀变体(Blazars of Uncertain type,BZUs)分为蝎虎天体候选体和平谱射电类星体候选体,并通过特征工程和网格搜索方法提高分类准确率。综合4种分类器的分类结果,将判别概率阈值设为0.8,得到33个蝎虎天体候选体和119个平谱射电类星体候选体。展开更多
文摘The origin of ultra high energy cosmic rays (UHECRs) is still an open question in astroparticle physics. TeV blazars are a small group of active galactic nuclei (AGNs). They all have been observed in TeV gamma ray band, and show violent variabilities in flux at all wavelengths. So it is believed that they have abilities to produce UHECRs. To judge whether the TeV blazars can be the candidates of the origin of UHECRs, we collect the information of emission region of 38 TeV blazars, and estimate the maximum energy that the charged particle can be accelerated there. The results show that TeV blazars have abilities to accelerate cosmic rays to the energy above 1018?eV, some even higher than 1020?eV, and they may be the sources of UHECRs.
基金supported by the National Natural Science Foundation of China (Grant Nos. 10778702 and 10803005)the 973 Program (2009CB824800)Yunnan Province under grant 2009 OC
文摘The multiband nonthermal emissions in radio, X-ray, and very high-energy（VHE） γ-ray bands from two distant blazars, H 2356–309 and 1ES 1218＋304, havebeen detected, and, especially from recent observations with the Suzaku, MAGICand VERITAS telescopes, clearly reveal nonthermal power-law spectra. We study thebroadband nonthermal spectra of the two sources by using a combination of a one-zone homogeneous synchrotron self-Compton （SSC） model and an inhomogeneousconical jet model, where the new external background light （EBL） model is taken intoaccount. The results show that （1） the nonthermal emissions of the two blazars, rang-ing from X-rays to VHE γ-rays, are from the homogeneous zone whereas the emis-sions in the radio bands can be explained as the radiation from the inhomogeneousconical jet; （2） a strict lower-limit EBL model can be used to explain their observedspectra well.
文摘利用支持向量机(Support Vector Machine,SVM)、随机森林(Random Forest,RF)、集成学习(Ensemble Learning,EM)和多层感知机(Multi-Layer Perceptron,MLP)将罗马5期耀变体多波段目录(The 5th edition of the Roma-BZCAT Multifrequency Catalogue of Blazars,5BZCAT)中227个不确定类型的耀变体(Blazars of Uncertain type,BZUs)分为蝎虎天体候选体和平谱射电类星体候选体,并通过特征工程和网格搜索方法提高分类准确率。综合4种分类器的分类结果,将判别概率阈值设为0.8,得到33个蝎虎天体候选体和119个平谱射电类星体候选体。
