Simulations of radiation driven winds from Keplerian discs

TL;DR

This paper investigates how radiation, thermal pressure, and centrifugal forces drive winds from accretion discs around stellar black holes, revealing the impact of radiation drag on wind speed and mass outflow.

Contribution

It introduces a detailed simulation of wind ejection from Keplerian discs, highlighting the significant role of radiation drag in reducing wind speeds and outflow rates.

Findings

Winds reach up to 0.1c in speed at high accretion rates.

Radiation drag significantly reduces wind terminal speeds.

Mass outflow rates decrease due to radiation drag effects.

Abstract

We study the ejection of winds from thin accretion discs around stellar mass black holes and the time evolution of these winds in presence of radiation field generated by the accretion disc. Winds are produced by radiation, thermal pressure and the centrifugal force of the disc. The winds are found to be mildly relativistic, with speeds reaching up to terminal speeds $0.1$ for accretion rate $4$ in Eddington units. We show that the ejected matter gets its rotation by transporting angular momentum from the disc to the wind. We also show that the radiation drag affects the accretion disc winds in a very significant manner. Not only that the terminal speeds are reduced by an order of magnitude due to radiation drag, but we also show that the non-linear effect of radiation drag, can mitigate the formation of the winds from the matter ejected by the accretion disc. As radiation drag reduces the velocity of the wind, the mass outflow rate is reduced in its presence as well.