Non-thermal emission from the termination of microquasar jets interacting with the interstellar medium




We propose a model to account for the non-thermal radiation due to the interaction of the jet termination shock of a microquasar (MQ) with its ambient interstellar medium (ISM). In this model, relativistic electrons and protons are accelerated simultaneously in the jet termination reverse shock. These particles then diffuse into the ISM from a region shocked by the reverse shock and interact with another region shocked by the forward shock, which can produce detectable photon fluxes at different energies. Using numerical calculation, we present various photon spectra for a general MQ produced via synchrotron, inverse Compton, synchrotron self-Compton, relativistic bremsstrahlung and π0-decay emissions. Finally, we apply this model to the MQ Cygnus X-1 by modifying various parameters. Our results show the extent of radiative emission from the ISM–jet interaction region, which may be detectable by the current Fermi Large Area Telescope and the future Cherenkov Telescope Array.