Short-timescale variability in the broadband emission of the blazars mkn421 and mkn501

Abstract We analyse ASCA satellite X-ray data and Whipple Observatory TeV γ-ray data from the Blazars Mkn421 and Mkn501 for short timescale variability using the excess pair fraction method. We discuss the method and the data as well as EPF sensitivity to these data. We find that in these data sets, we can rule out an amplitude of variability greater than 10% on timescales less than 10 min from both sources and at both wavelengths at a confidence level of >99.7%. We discuss briefly the implications of low amplitudes of variability on short timescales for the beamed jet of relativistic particles probably producing these radiations and, we derive limits from the data on the local percentage change in both the lepton density and the magnetic field strength in these Blazar jets.