Impact of ordered and disordered magnetic fields on multiwavelength emission of blazars

Abstract

We present a detailed analysis of the effects of magnetic field topology on the spectral energy distribution (SED) and spectral variability patterns (SVPs) of blazars. In order to study these effects, we have extended our time-dependent leptonic jet model (in the internal shock scenario) to include the dependence of the synchrotron emissivity on the angle between the photon direction and the magnetic field in the plasma frame. We have explored the effects of different magnetic field geometries, such as parallel, perpendicular, oblique, toroidal, and helical, on the simulated SEDs and SVPs of a generic blazar for both purely ordered and disordered components of fields. These considerations provide either upper or lower limits to the impact on blazar emission, depending on the fraction of a disordered component present and the viewing angle. The results of our work point out some of the signatures that the orientations can leave on the SEDs and SVPs of a blazar. For example, in the case of a purely oblique field, if the magnetic field is aligned along the line of sight (in the plasma frame), it results in an annulment of the synchrotron component while keeping the flux level of the high-energy component intact. On the other hand, in the presence of a disordered component, the impact of an oblique field is reduced, and the same effect is not observed