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

TL;DR

This paper investigates how intense radiation from accretion discs interacts with relativistic jets via Compton scattering, leading to jet acceleration, heating, and shock formation, with implications for jet speeds and composition.

Contribution

It introduces a detailed analysis of radiation-driven relativistic jets under Compton scattering, revealing new acceleration mechanisms and jet behaviors not seen in Thomson scattering regimes.

Findings

Jets can be accelerated starting with very low thermal energy.

Radiation can drive bound matter to relativistic speeds.

Jets exhibit a minimum terminal speed for given disc luminosity.

Abstract

Interaction of intense radiation from the underlying accretion disc with steady, general-relativistic jet is studied. The radiation field imparts momentum as well as energy on 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 ${{\rm e}^--{\rm p}^+}$ 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 few tens for highly luminous discs.