Some statistical correlation analyses for Fermi/LAT Blazars

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 γ-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 γ-ray luminosity for 4 the sub-classes of blazars also follow the blazars sequence. Also, there was close anti-correlations between the difference of two γ-ray photon spectral indices and the logarithm of the ratio of two γ-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.