RELATIVISTIC HADRONS AND THE ORIGIN OF RELATIVISTIC OUTFLOWS IN ACTIVE GALACTIC NUCLEI

We examine the hydrodynamic origin of relativistic outflows in active galactic nuclei (AGN). Specifically, we propose that the presence of a population of relativistic hadrons in the AGN ''central engine'' and the associated neutron production suffices to produce outflows which u nder rather general conditions could be relativistic. The main such co ndition is that the size of the neutron production region be larger th an the neutron flight path c tau(n) similar or equal to 3 x 10(13) cm. This condition guarantees that the mean energy per particle in the pr oton fluid, resulting from the decay of the neutrons outside their pro duction region, be greater than the proton rest mass. The expansion of this fluid can then lead naturally to a relativistic outflow by conve rsion of its internal energy to directed motion. We follow the develop ment of such flows by solving the mass, energy as well as the kinetic equation for the proton gas in steady state, taking into account the s ource terms due to the decay of relativistic neutrons and adiabatic lo sses due to expansion. This process allows one to compute accurately t he adiabatic index of the expanding gas, and in conjunction with Berno ulli's equation the detailed evolution of the bulk Lorentz factor. We further examine the role of large-scale magnetic fields in confining t hese outflows to produce the jets observed at larger scales.