A study of radial self-similar non-relativistic MHD outflow models: parameter space exploration and application to the water fountain W43A

TL;DR

This paper explores a wide parameter space of non-relativistic MHD outflow models, analyzing their launching mechanisms and applying findings to the water fountain W43A with observational data.

Contribution

It introduces a new numerical scheme for semi-analytical solutions of MHD outflows and applies it to a specific astrophysical object, W43A.

Findings

Identified force combinations leading to successful jet launching.

Mapped global properties of various outflow solutions.

Applied models to interpret observational data of W43A.

Abstract

Outflows, spanning a wide range of dynamical properties and spatial extensions, have now been associated with a variety of accreting astrophysical objects, from supermassive black holes at the core of active galaxies to young stellar objects. The role of such outflows is key to the evolution of the system that generates them, for they extract a fraction of the orbiting material and angular momentum from the region close to the central object and release them in the surroundings. The details of the launching mechanism and their impact on the environment are fundamental to understand the evolution of individual sources and the similarities between different types of outflow-launching systems. We solve semi-analytically the non-relativistic, ideal, magnetohydrodynamics (MHD) equations describing outflows launched from a rotating disk threaded with magnetic fields using our new numerical scheme. We present here a parameter study of a large sample of new solutions. We study the different combinations of forces that lead to a successfully launched jet and discuss their global properties. We show how these solutions can be applied to the outflow of the water fountain W43A for which we have observational constraints on magnetic field, density and velocity of the flow at the location of two symmetrical water maser emitting regions.