SIMBAD references

We present a formalism to predict the polarization degree (PD) for synchrotron emission from particles having a specified energy distribution in the presence of an ordered and random magnetic field configuration. The broadband spectral energy distribution and the X-ray and optical PD data for Mrk 501 have been fitted using the formalism. As reported earlier, we find that for a broken power-law particle energy distribution the PD cannot be explained, unless it is assumed that the higher-energy particles experience a higher ordered magnetic field compared to the lower-energy ones. On the other hand, a log parabola particle energy distribution can explain the observed higher X-ray PD compared to the optical, even when all the particles experience the same magnetic configuration. We discuss the possibility of distinguishing the two scenarios using future observations.