Radiative Transfer in Relativistic Accretion-Disk Winds

TL;DR

This paper analyzes radiative transfer in relativistic accretion disk winds, revealing how relativistic effects like Doppler boosting alter observed intensities and produce a relativistic peaking effect.

Contribution

It provides an analytical solution for emergent intensity in relativistic winds and highlights the relativistic peaking effect caused by wind motion.

Findings

Emergent intensity is enhanced in the flow direction due to relativistic effects.

The limb-darkening effect disappears in equilibrium relativistic flows.

Relativistic winds and jets exhibit strong directional intensity enhancement.

Abstract

Radiative transfer in a relativistic accretion disk wind is examined under the plane-parallel approximation in the fully special relativistic treatment. For an equilibrium flow, where the flow speed and the source function are constant, the emergent intensity is analytically obtained. In such an equilibrium flow the usual limb-darkening effect does not appear, since the source function is constant. Due to the Doppler and aberration effects associated with the relativistic motion of winds, however, the emergent intensity is strongly enhanced toward the flow direction. This is the {\it relativistic peaking effect}. We thus carefully treat and estimate the appearance of relativistic winds and jets, when we observe them in an arbitrary direction.