[Commits] [svn:einsteintoolkit] Paper_EinsteinToolkit_2010/ (Rev. 60)

[schnetter at cct.lsu.edu]

User: eschnett
Date: 2011/04/17 09:40 PM

Modified:
 /
  ET.tex

Log:
 Update QLM section

File Changes:

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

File [modified]: ET.tex
Delta lines: +17 -6
===================================================================
--- ET.tex	2011-04-18 02:30:45 UTC (rev 59)
+++ ET.tex	2011-04-18 02:40:49 UTC (rev 60)
@@ -1325,16 +1325,27 @@
 the domain as these quantities are only properly interpretable when
 calculated at infinity.
 
-Second, there are the quasi-local measures of mass and momentum. From 
+Second, there are the quasi-local measures of mass and angular momentum. From 
 any \ahz{s} found during the spacetime, both 
 \codename{AHFinderDirect} and \codename{AHFinder} output the 
 corresponding mass derived from the area of the horizon $m_H = 
-\sqrt{A/(16\pi)}$.  In addition, the module \codename{QuasiLocalMeasures} 
-takes a specified surface, generally a previously located \ahz{}
-and calculates the mass, spin and their moments, among other quantities,
-on the surface based on the isolated and dynamical horizon framework.
-\todo{... is this what it does? ...} 
+\sqrt{A/(16\pi)}$.
 
+In addition, the module \codename{QuasiLocalMeasures} implements
+certain equations from the isolated and dynamical horizon formalisms,
+as well as certain extensions defining quasi-local quantities;
+quasi-local quantities are quantities that are gauge independent, but
+depend on the choice of a particular two-sphere in a spacetime. In
+this sense, \codename{QuasiLocalMeasures} can provide
+gauge-independent measures of e.g.\ mass and angular momentum of
+regions of the spacetime enclosed in a two-sphere.
+\codename{QuasiLocalMeasures} takes as input a horizon surface any
+other surface that the user specifies, such as a large coordinate
+sphere, and calculates can calculate mass, angular momentum, or other
+quantities such as the Weyl or Ricci scalars, multipole moments of the
+horizon geometry, or the three-volume element of the horizon world
+tube.
+
 Finally, the module \codename{HydroAnalysis} additionally locates the 
 center of mass as well as the point of maximum rest mass density of a 
 matter field.