The correlation between γ $\gamma$ -photon energy and synchrotron peak frequency for Fermi BL Lac objects

Abstract

In this paper, the average energy of the $\gamma$ -photon ( $E_{\mathrm {a},\mathrm{ph}}$ ) is calculated and the correlation between $\log E_{\mathrm{a},\mathrm{ph}}$ and the logarithm of the synchrotron peak frequency ( $\log\nu_{\mathrm{p}}$ ) is discussed for a sample of 620 BL Lac objects. The results show that there exists a positive correlation between the $\gamma$ -photon energy and the synchrotron peak frequency for BL Lac objects, which implies that the $\gamma$ -ray emissions are related to the low-energy emissions of radio to X-ray bands, and the high energetic $\gamma$ -ray emissions are only partially from the synchrotron self-Compton process (SSC) for BL Lac objects.