Radiative Processes In Extragalactic Large-Scale Jets

Abstract

About one thousand extragalactic large-scale jets are known, and a few tens of them are confirmed sources of infrared, optical, or X-ray photons. Multiwavelength emission comming directly from these outflows is always non-thermal in origin. This fact constitutes a primary difficulty in extracting unknown parameters of large-scale jets, since the non-thermal featureless continua do not allow to infer undoubtfully (or even at all) bulk velocities and composition of the radiating plasma. In addition, arcsecond spatial resolution, limited sensitivity and narrow energy bands of the best high-frequency telescopes like Spitzer, Hubble and Chandra, preclude precise constraints on the spectral and morphological properties of the discussed objects. Nevertheless, new multiwavelength observations have substantially enriched our knowledge on extragalactic large-scale jets, in many aspects, however, by means of challenging previous predictions and expectations. In this short contribution I will concentrate on the following issue: what can be learned by analyzing broad-band emission of the discussed objects about particle acceleration processes acting thereby and about jet internal parameters.