Power Spectral Distribution of the BL Lac Object S5 0716+714

Abstract

Observational data in the BVRI bands of the variable BL Lacertae Object S5 0716+714 is discussed from the point of view of its Power Spectral Distribution (PSD). A model of the type $P(f) = \beta f^{-1} [1 + (\frac{f} {\delta}) ^{\alpha -1}]^{-1} + \gamma $ is fitted to the data for four null hypothesis and the Bayesian $p$ parameter for the fits is calculated. Spectral slopes with values ranging from 1.083 to 2.65 are obtained, with medium values for each band of $\bar{\alpha}_B =2.028$, $\bar{\alpha}_V = 1.809$, $\bar{\alpha}_R = 1.932$ and $\bar{\alpha}_I = 1.54$ respectively. These values confirm conclusions of previous studies, namely that the source is turbulent. Two disk models, the standard prescription of the Shakura-Sunyaev disk and magnetized disks exhibiting MagnetoRotational Instability, were discussed. We found that it is unlikely that they explain this set of observational data.