A comparative study of Bondi-type and radiative outflows around compact objects

摘要

Astrophysical jets are observed to come out with relativistic speed and are extremely collimated. Here we study the effect of momentum deposition by hot photons from the torus like, puffed up inner region of the accretion disc on radial outflows. We calculate the radiative momentum deposition force on the outflows and find that there is a focusing effect. The size of the radiating torus completely determines the location where the radiative force is maximum. We solve the steady state equations of motion of the radial outflow, in Schwarzschild geometry to show that the acceleration achieved is appreciable, when it is compared with Bondi-type outflow. We also show that, the photon momentum deposition force results in bringing the sonic point closer to the black hole thereby resulting in a more energetic outflows as compared to purely thermally driven outflow. Particularly interesting is that in many cases, where bound matters are freed and driven off as outflows after sufficient momentum is deposited. [References: 14]