Are the hotspots of radio galaxies the sites of in situ acceleration of relativistic particles?

Using a large set of optically detected hotspots in powerful extragalactic double radio sources, we examine the basic question of whether the detectio n of optical synchrotron radiation requires in situ acceleration of relativ istic electrons within the hotspots/lobes. For this, we take into account t he jet's bulk relativistic motion, as well as its likely misalignment from the plane of the sky. Together, both these factors can drastically reduce t he apparent range of the ultra-relativistic electrons ejected from the nucl eus in the form of a jet. The conventionally adopted parameter space for th e fundamental variables, namely, the hotspot magnetic field, radio source o rientation angle relative to the line-of-sight and the bulk speed of the je t plasma, is considered. We find that the observed optical/near-IR synchrot ron emission of the hotspots can be explained even if the radiating relativ istic electrons were accelerated exclusively within the nuclear region, pro vided the energy losses incurred by the electrons during their transport do wn the jet are dominated by inverse Compton upscatterings of the cosmic mic rowave background photons. Under this circumstance, in situ acceleration of relativistic electrons inside the hotspots or lobes is not found to be man dated by their reported optical/near-infrared detections.