Fermi Gamma-ray Space Telescope

Time-Domain Anaysis of Kepler Blazar W2R 1926+42

M. Sasada
S. Mineshige, S. Yamada, H. Negoro

Abstract:

Blazars show violent and fast variabilities with timescales ranging from minutes to decades. Although these variations provide information of its emission regions, the variation mechanism is still under debate. We analyze the Kepler monitoring data of a blazar W2R 1926+42 with a duration of 100 days to examine the properties of its fast variability by means of the power spectrum density (PSD) and 'shot analysis' techniques. The PSD of its light curve can not represent a simple powerlaw function, but a powerlaw plus squared Lorentzian function. This result indicates that the light curve has a characteristic timescale as the break frequency in the PSD. We make a mean light-variation profile, which is obtained by aligning the peaks of rapid variations in the light curve. This mean profile is composed of a spiky-shape component around the time of peak and slow-varying components. This spiky feature is well represented by an exponential rise of 0.042 day and an exponential decay of 0.059 day. The average of these timescales are well consistent with the timescale of the characteristic frequency of 0.045 day. This indicates the curvature of the PSD is corresponding to the spiky component seen in the mean profile of rapid variations.