Radiation driving and heating of general relativistic jets under a Compton-scattering regime

Abstract

Interaction of intense radiation from the underlying accretion disc with a steady, generalrelativistic jet is studied. The radiation field imparts momentum as well as energy to the outflowing jet under Compton scattering. As a result, the jet gains momentum and is simultaneously heated up. Jets can be classified as types A, B and C according to their base properties. We found that A-type jets can undergo shock transition. It is also shown that, in the Compton-scattering regime, radiation can drive jets starting with very small thermal energy at the base (B- and C-type jets), such that radiation can even accelerate bound matter (generalized Bernoulli parameter E < 1) in the form of relativistic transonic jets. This is in stark contrast to radiatively driven jets in the Thomson-scattering regime, where transonic jets were obtained only for E > 1. We also show that, for a given disc luminosity, jets in the Compton-scattering regime exhibit a minimum terminal speed, unlike in the Thomson-scattering domain. Further, the impact of accretion-disc luminosity and jet plasma composition is studied. The e−−p+ jets are accelerated up to Lorentz factors of about a few, while for lepton-dominated jets the minimum Lorentz factor exceeds 10 for moderate disc luminosities and can go up to a few tens for highly luminous discs.