A sample including 664 blazars （301 Flat Spectrum Radio Quasars and 363 BL Lacs） with ）γ-ray data in both 1FGL and 2FGL catalogues were selected. The average values of both y-photon average energy and the photon s...A sample including 664 blazars （301 Flat Spectrum Radio Quasars and 363 BL Lacs） with ）γ-ray data in both 1FGL and 2FGL catalogues were selected. The average values of both y-photon average energy and the photon spectral index for FSRQs, LBLs, IBLs and HBLs, follow the blazars sequence, FSRQs → LBLs →IBLs → HBLs. The slopes of correlation between photon spectral index and ）,-ray luminosity for 4 the sub-classes of blazars also follow the blazars sequence. Also, there was close an- ti-correlations between the difference of two ）,-ray photon spectral indices and the logarithm of the ratio of two y-ray luminosities from 2FGL and 1FGL catalogs. It implies that the spectrum becomes flat when the source becomes brighter in high energetic γ-ray band. Lastly, the Kolmogolov-Smirnov test （KS test） of the average γ-photon energy showed that HBLs differs from LBLs and FSRQs, while there was no clear difference between LBLs and FSRQs, which implied that the γ-ray emissions in LBLs and FSRQs may be a result of the same emission mechanism.展开更多
This study uses a parabolic equation to fit the Inverse Compton (IC) spectral component of 3743 blazars (794 FSRQs,1432 BLLacs,and 1517 BCUs) from the 4FGL-DR3 catalog.Some mutual correlations are investigated,and a B...This study uses a parabolic equation to fit the Inverse Compton (IC) spectral component of 3743 blazars (794 FSRQs,1432 BLLacs,and 1517 BCUs) from the 4FGL-DR3 catalog.Some mutual correlations are investigated,and a Bayesian classification is performed to the IC peak frequencies.Our analyses draw the following conclusions:(1) The Bayesian classification shows two components with a dividing boundary of log(v_(p)^(IC)/Hz)pIC=22.9.Therefore,the 3743 blazars are divided into low IC peak frequency(LCP) blazars and high IC peak frequency (HCP) blazars.(2) A strong linear correlation exists between IC peak frequency(logv_(p)^(IC)) and γ-ray photon spectral index (Γ).The IC peak frequency can be estimated by an empirical relation logv_(p)^(IC)=–4.5·Γ+32.8 for BL Lacs and logv_(p)^(IC)=4.0+31.4pICfor FSRQs,which is consistent with the result by Abdo et al.(3) The ICspectral curvature and IC peak frequency are not as closely related as the synchrotron curvature and the synchrotron peak frequency.(4) An anti-correlation exists between IC peak frequency and IC peak luminosity,implying that as the IC peak frequency in the γ-ray band decreases,the source becomes more luminous.The beaming effect is stronger for the source with a lower IC peak frequency.(5) Positive correlations exist between IC and synchrotron components for both peak frequencies and peak fluxes,but no clear correlation exists between IC curvature and synchrotron curvature.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.10633010 and 11173009)the construct program of the key discipline in Hunan University of Arts and Sciencethe research fund of Hunan University of Arts and Science(Grant No.JJZD201101)
文摘A sample including 664 blazars （301 Flat Spectrum Radio Quasars and 363 BL Lacs） with ）γ-ray data in both 1FGL and 2FGL catalogues were selected. The average values of both y-photon average energy and the photon spectral index for FSRQs, LBLs, IBLs and HBLs, follow the blazars sequence, FSRQs → LBLs →IBLs → HBLs. The slopes of correlation between photon spectral index and ）,-ray luminosity for 4 the sub-classes of blazars also follow the blazars sequence. Also, there was close an- ti-correlations between the difference of two ）,-ray photon spectral indices and the logarithm of the ratio of two y-ray luminosities from 2FGL and 1FGL catalogs. It implies that the spectrum becomes flat when the source becomes brighter in high energetic γ-ray band. Lastly, the Kolmogolov-Smirnov test （KS test） of the average γ-photon energy showed that HBLs differs from LBLs and FSRQs, while there was no clear difference between LBLs and FSRQs, which implied that the γ-ray emissions in LBLs and FSRQs may be a result of the same emission mechanism.
基金supported by the National Natural Science Foundation of China(Grant Nos.U2031112,U2031201,and 11733001)the Guangdong Major Project of Basic and Applied Basic Research(Grant No.2019B030302001)+3 种基金the Research Fund of Hunan Education Department(Grant No.20C1273)the Science Research Grants from the China Manned Space Project(Grant No.CMS-CSST-2021-A06)the support from Astrophysics Key Subjects of Guangdong Province and Guangzhou Citysupported by the Guangzhou University(Grant No.YM2020001)。
文摘This study uses a parabolic equation to fit the Inverse Compton (IC) spectral component of 3743 blazars (794 FSRQs,1432 BLLacs,and 1517 BCUs) from the 4FGL-DR3 catalog.Some mutual correlations are investigated,and a Bayesian classification is performed to the IC peak frequencies.Our analyses draw the following conclusions:(1) The Bayesian classification shows two components with a dividing boundary of log(v_(p)^(IC)/Hz)pIC=22.9.Therefore,the 3743 blazars are divided into low IC peak frequency(LCP) blazars and high IC peak frequency (HCP) blazars.(2) A strong linear correlation exists between IC peak frequency(logv_(p)^(IC)) and γ-ray photon spectral index (Γ).The IC peak frequency can be estimated by an empirical relation logv_(p)^(IC)=–4.5·Γ+32.8 for BL Lacs and logv_(p)^(IC)=4.0+31.4pICfor FSRQs,which is consistent with the result by Abdo et al.(3) The ICspectral curvature and IC peak frequency are not as closely related as the synchrotron curvature and the synchrotron peak frequency.(4) An anti-correlation exists between IC peak frequency and IC peak luminosity,implying that as the IC peak frequency in the γ-ray band decreases,the source becomes more luminous.The beaming effect is stronger for the source with a lower IC peak frequency.(5) Positive correlations exist between IC and synchrotron components for both peak frequencies and peak fluxes,but no clear correlation exists between IC curvature and synchrotron curvature.
