User: tbode Date: 2011/04/28 02:13 PM

Modified: / ET.tex

Log: Analysis section: some rewriting.

File Changes:

Directory: / ============

File [modified]: ET.tex Delta lines: +20 -20 =================================================================== --- ET.tex 2011-04-28 18:45:59 UTC (rev 80) +++ ET.tex 2011-04-28 19:13:37 UTC (rev 81) @@ -1233,28 +1233,30 @@

\subsection{Analysis\pages{4 Tanja}} -It is beneficial to evaluate common analysis quantities online -rather than offline, in time-consuming post-processing procedures. -Beyond extracting physics, these quantities are often used as measures -of how accurately the simulation is progressing. Below we detail the -quantities available within Einstein Toolkit modules and the -assumptions and equations used by each. The analysis capabilities of -the Einstein Toolkit broadly fall into three categories: horizons, -masses and momenta, and gravitational waves. Many modules bridge these -these categories and some fall outside them. The latter are described -in the last subsection, including constraint monitoring and tools for -commonly required derived spacetime quantities. The following discussion -is meant as an overview of the most common tools rather than an -exhaustive list of functionality. In most cases, the analysis modules +It is often beneficial and sometimes necessary to evaluate analysis quantities +during the simulation rather than post-processing variable output. Beyond +extracting physics, these quantities are often used as measures of how +accurately the simulation is progressing. In the following, we describe the +common quantities available through Einstein Toolkit modules, and how different +modules approach these quantities with differing assumptions and algorithms. +The most common analysis quantities provided broadly fall into three +categories: horizons, masses and momenta, and gravitational waves. Several +modules bridge these categories and some fall outside them. The latter, are +described in the last subsection, including constraint monitoring and commonly +desired derived spacetime quantities. The following discussion is meant as an +overview of the most common tools rather than an exhaustive list of the +functionality provided by the Einstein Toolkit. In most cases, the analysis modules work on the variables stored in the base modules discussed in Sec.~\ref{sec:base_modules} (\codename{ADMBase}, \codename{TmunuBase}, and \codename{HydroBase}) to create as portable a tool as possible.

\subsubsection{Horizons} -For spacetimes which contain a \bh{,} the Einstein Toolkit provides -one module (\codename{EHFinder}) for finding event horizons and -two modules for finding \ahz{s} (\codename{AHFinder} -and \codename{AHFinderDirect}). +When spacetimes contain a \bh{,} localizing a \bh{'s} horizon are necessary +for describing time-dependent quasi-local measures of the \bh{} such as +mass and spin. The Einstein Toolkit provides two modules (\codename{AHFinder} +and \codename{AHFinderDirect}) for locating the \ahz{s}, defined locally on a +hypersurface. The module \codename{EHFinder} is also available to search an +evolved spacetime for the globally defined event horizons.

% Event horizon The event horizon module \codename{EHFinder}~\cite{Diener:2003jc} @@ -1530,9 +1532,7 @@ where $S_i=-\frac{1}{\alpha} \left( T_{i0} - \beta^j T_{ij} \right)$. The difference between these modules lies in how they access the stress energy tensor $T_{\mu\nu}$, as the module \codename{ADMConstraints} -uses a \todo{deprecated?} -\todo{ES: yes, deprecated} -functionality which does not require storage +uses a deprecated functionality which does not require storage for $T_{\mu\nu}$.

Finally, \codename{ADMAnalysis} calculates a variety of derived spacetime