摘要
The curvature of the γ-ray spectrum in blazars may reflect the intrinsic distribution of emitting electrons, which will further give some information on the possible acceleration and cooling processes in the emitting region. The γ-ray spectra of Fermi blazars are normally fitted either by a single power-law（PL） or a log-normal（call Logarithmic Parabola, LP） form. The possible reason for this difference is not clear. We statistically explore this issue based on the different observational properties of 1419 Fermi blazars in the 3 LAC Clean Sample. We find that the γ-ray flux（100 Me V–100 Ge V） and variability index follow bimodal distributions for PL and LP blazars, where the γ-ray flux and variability index show a positive correlation. However, the distributions of γ-ray luminosity and redshift follow a unimodal distribution. Our results suggest that the bimodal distribution of γ-ray fluxes for LP and PL blazars may not be intrinsic and all blazars may have an intrinsically curved γ-ray spectrum, and the PL spectrum is just caused by the fitting effect due to less photons.
The curvature of the γ-ray spectrum in blazars may reflect the intrinsic distribution of emitting electrons, which will further give some information on the possible acceleration and cooling processes in the emitting region. The γ-ray spectra of Fermi blazars are normally fitted either by a single power-law（PL） or a log-normal（call Logarithmic Parabola, LP） form. The possible reason for this difference is not clear. We statistically explore this issue based on the different observational properties of 1419 Fermi blazars in the 3 LAC Clean Sample. We find that the γ-ray flux（100 Me V–100 Ge V） and variability index follow bimodal distributions for PL and LP blazars, where the γ-ray flux and variability index show a positive correlation. However, the distributions of γ-ray luminosity and redshift follow a unimodal distribution. Our results suggest that the bimodal distribution of γ-ray fluxes for LP and PL blazars may not be intrinsic and all blazars may have an intrinsically curved γ-ray spectrum, and the PL spectrum is just caused by the fitting effect due to less photons.
基金
supported by the National Natural Science Foundation of China(Grant Nos.11763005,11622324,11573009,11763002,U1431111 and U1431126)
supported by the Research Foundation for Advanced Talents of Liupanshui Normal University(LPSSYKYJJ201506)
the Open Fund of Guizhou Provincial Key Laboratory of Radio Astronomy and Data Processing
the Physical Electronic Key Discipline of Guizhou Province(ZDXK201535)
the Natural Science Foundation of the Department of Education of Guizhou Province(QJHKYZ[2015]455)
the Research Foundation of Liupanshui Normal University(LPSSYDXS1514 and LPSSY201401)
