Skip to main content Accessibility help
×
Hostname: page-component-76fb5796d-45l2p Total loading time: 0 Render date: 2024-04-25T13:11:21.321Z Has data issue: false hasContentIssue false

F - Collisionless matter evolution in axisymmetry: basic equations

Published online by Cambridge University Press:  05 March 2013

Thomas W. Baumgarte
Affiliation:
Bowdoin College, Maine
Stuart L. Shapiro
Affiliation:
University of Illinois, Urbana-Champaign
Get access

Summary

Here we list the key equations describing a mean-field, particle simulation scheme that can treat the evolution of collisionless matter in axisymmetry according to general relativity. The scheme is a generalization of the one described in Chapter 8.2 for spherical systems and employs the standard ADM form of the field equations as listed in Box 2.1. We adopt spherical polar spacetime coordinates (t, r, θ,ϕ), assume axisymmetry and specialize to the case where there is no net angular momentum. In axisymmetry all quantities are functions only of (t, r, θ). We also impose maximal slicing and quasi-isotropic spatial coordinates as our gauge conditions. This spatial gauge condition reduces to isotropic coordinates for Schwarzschild geometry. The field equations listed below constitute a fully constrained approach to solving the Einstein field equations for this problem, i.e., one which solves all of the constraint equations in lieu of integrating evolution equations for some of the variables. Fully constraint schemes have the advantage over unconstrained schemes that the constraints are guaranteed to be satisfied at all times, which may in some cases also eliminate some instabilities associated with the evolution equations. Their disadvantage is that the constraints constitute elliptic equations, which typically require more computational resources to solve than explicit time evolution equations. This disadvantage is not so severe, however, in 1 + 1 or 2 + 1 spacetimes. A similar set of variables and field equations to the ones summarized below has been used to simulate the gravitational collapse of hydrodynamic fluids and vacuum gravitational waves6 in nonrotating, axisymmetric spacetimes, as well as the head-on collision of neutron stars.

Type
Chapter
Information
Numerical Relativity
Solving Einstein's Equations on the Computer
, pp. 629 - 633
Publisher: Cambridge University Press
Print publication year: 2010

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

Save book to Kindle

To save this book to your Kindle, first ensure coreplatform@cambridge.org is added to your Approved Personal Document E-mail List under your Personal Document Settings on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part of your Kindle email address below. Find out more about saving to your Kindle.

Note you can select to save to either the @free.kindle.com or @kindle.com variations. ‘@free.kindle.com’ emails are free but can only be saved to your device when it is connected to wi-fi. ‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.

Find out more about the Kindle Personal Document Service.

Available formats
×

Save book to Dropbox

To save content items to your account, please confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account. Find out more about saving content to Dropbox.

Available formats
×

Save book to Google Drive

To save content items to your account, please confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account. Find out more about saving content to Google Drive.

Available formats
×