Shaping Outflows and Jets by Ambient Pressure: a Unified Framework

TL;DR

This paper introduces a unified theoretical framework for astrophysical outflows, demonstrating that their shapes and behaviors are governed by ambient pressure gradients, which are consistent across different cosmic scales.

Contribution

The authors extend classical nozzle theory to include ambient pressure effects, providing a universal model that explains outflow morphology from stellar to galactic scales.

Findings

Pressure profiles follow a power-law near -2

Outflow morphology is governed by ambient pressure gradients

Model applies to diverse astrophysical outflows

Abstract

Astrophysical outflows are ubiquitous across cosmic scales, from stellar to galactic systems. While diverse launching mechanisms have been proposed, we demonstrate that these outflows share a fundamental commonality: their morphology follows the physics of pressure-confined supersonic flows. By extending classical deLaval nozzle theory to account for ambient pressure gradients, we present a unified framework that successfully describes outflows from young stellar objects to active galactic nuclei. Our model reveals a remarkable consistency in pressure profiles, characterized by a power-law exponent near minus two, independent of the internal characteristics of the outflow or the nature of central engine. This discovery suggests a universal mechanism for outflow collimation and acceleration, bridging the gap between theoretical models and observational features across a wide range of astronomical scales.