Symmetric variability of gamma-ray emitting blazars

Symmetric and triangle-shaped flux variability in X-ray and gamma-ray light curves has been observed in many blazars. In this work, we carried out a statistical approach to X-ray and gamma- ray variability characteristics of flares in gamma-ray emitting blazars using archive data. Our results suggest that the time scale of the rise time in flares is equal to that of the decay time. Our results also suggest that the harder flare spectra show the larger spectral variability for the X-ray and gamma-ray flares. In this proceeding, we also discuss a simple model that represent the characteristic X-ray and gamma-ray variability: nearly equal the rise time and decay time, the harder spectral change with the increasing flux, and the larger flare spectral change with the harder spectrum.