Hydrodynamic Simulations of Relativistic Flows: From Pulsars to Parsec-Scale Jets

Regents Of The University Of Michigan - Ann Arbor, Ann Arbor MI

Investigators

Abstract

AST 0205105 Hughes Jets of gas, flowing at close to the speed of light, are a common feature of our Universe and are found wherever compact objects such as black holes capture material. In this project, computer simulations of these jets will be used to advance our understanding of such energetic flows. In particular these simulations will be designed to help us understand how such jets can penetrate their environment without disruption and also shed light on the nature of the `engines' which produce them. The technique used in this study incorporates Special Relativity and uses state-of-the-art methods originally designed for fields such as aerospace engineering. It enables large computations to be performed with modest computer resources, thus allowing an exploration of many facets of the problem. Among these are: how shock waves form in the gas flow, and how the flow responds to impacting dense surrounding material, or being spun around in space due to changes in the direction of the engine's nozzle. An important aspect of the study is that it provides a probe of the poorly understood jets of stellar binary systems, and should reveal the extent to which these really are mini-quasars -- scaled down versions of active galaxies. The same technique is applied to the nebulae that result from pulsar winds, where moving through the ambient medium causes the nebula to be swept back into a tail of gas, similar to the galactic and stellar jets. Understanding these `wind nebulae' will provide insight into the flow from the pulsar itself, which is not directly observable. ***