Viscous boundary layers of radiation-dominated, relativistic jets. II. The free-streaming jet model

TL;DR

This paper introduces a boundary layer model for radiation-dominated, relativistic jets, focusing on free-streaming jets and their observational implications, especially for gamma-ray bursts and tidal disruption events.

Contribution

It presents a novel free-streaming jet boundary layer model with solutions for ultrarelativistic flows dominated by radiation, expanding understanding of jet-environment interactions.

Findings

Jets entrain material from surroundings.

Jet cores have lower scatterer density and harder photon spectra.

Model applicable to gamma-ray bursts and tidal disruption events.

Abstract

We analyze the interaction of a radiation-dominated jet and its surroundings using the equations of radiation hydrodynamics in the viscous limit. In a previous paper we considered the two-stream scenario, which treats the jet and its surroundings as distinct media interacting through radiation viscous forces. Here we present an alternative boundary layer model, known as the free-streaming jet model -- where a narrow stream of fluid is injected into a static medium -- and present solutions where the flow is ultrarelativistic and the boundary layer is dominated by radiation. It is shown that these jets entrain material from their surroundings and that their cores have a lower density of scatterers and a harder spectrum of photons, leading to observational consequences for lines of sight that look "down the barrel of the jet." These jetted outflow models may be applicable to the jets produced during long gamma-ray bursts and super-Eddington phases of tidal disruption events.