Variability and Spectral Cutoff of Bright TeV Gamma-Ray Blazars

Blazars constitute the largest class of extragalactic sources detected by gamma-ray telescopes. The combination of high luminosities and strong variabilities observed in these sources indicates that gamma rays are an important component of the relativistic jet thought to characterize blazars. The gamma-ray spectra of blazars show intrinsic curvatures that cannot be accounted for by the absorption effect of extragalactic background light alone. Precise quantification of the gamma-ray spectral cutoff can strongly constrain the acceleration and cooling processes of the relativistic particles in blazar jets, but requires good statistics and a wide energy coverage. We perform spectral analysis of a selected sample of TeV blazars, observed by VERITAS and Fermi-LAT, across a wide range of gamma-ray energies. The variability in both GeV and TeV gamma-ray bands is investigated to identify periods with a steady flux, during which the average gamma-ray spectra can be parameterized to allow for a strong constraint on spectral cutoff without the risk of mixing different flux states. The flux and spectral variability of these blazars are also investigated. An update on our findings will be presented.