Kinetic powers of the relativistic jets in Mrk 421 and Mrk 501

Using the standard one-zone synchrotron self-Compton (SSC) model and Markov chain Monte Carlo (MCMC) technique, we systematically analyze quasi-simultaneous multi-wavelength (MWL) spectral energy distributions (SEDs) of Mrk 421 501 during states relatively low activity. With this in place, a semi-analytical method is developed to examine uncertainty jet power estimation caused by degeneracy radiative models. The method, combination with MCMC allows us explore properties over wide range variability timescale. Our results seem support: (1) In both jets are powered rapidly rotating black holes (BHs). BH spin could be lower than that or possibility they equal under assumption Blandford-Znajek mechanism. (2)The losses, which used form large-scale radio structure, important for reconciling differences kinetic derived from observations structure SED fitting results. Moreover, losses propagation more significant 421.