User: knarf Date: 2011/11/11 10:18 AM

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File [modified]: ET.tex Delta lines: +25 -22 =================================================================== --- ET.tex 2011-11-11 15:34:53 UTC (rev 185) +++ ET.tex 2011-11-11 16:18:21 UTC (rev 186) @@ -151,30 +151,28 @@ been closely tied to the availability and ease-of-use of enabling software and computational infrastructure. This document describes the Einstein Toolkit, which provides such an infrastructure, -developed openly and available freely with support from +developed openly and made available freely with grant support from the National Science Foundation. -%under the grant numbers 0903973/0903782/0904015 (CIGR).

Now is a particularly exciting time for numerical relativity and relativistic astrophysics, with major advances having been achieved in the study of astrophysical systems containing black holes (BHs) -and neutron stars (NSs). While the first fully general relativistic (GR) +and neutron stars (NSs). The first fully general relativistic (GR) simulations of merging NS-NS binaries were reported in 1999, with further advances for the next few years~\cite{Shibata:1999wm,Shibata:2002jb, -Shibata:2003ga,Shibata:2005ss,Shibata:2006nm}, systems containing BHs proved -much more numerically intractable until 2005. That year, computational -breakthroughs were made using a generalized harmonic gauge (GHG) -\cite{Pretorius:2005gq} and then a ``moving puncture'' approach +Shibata:2003ga,Shibata:2005ss,Shibata:2006nm}. However, systems containing BHs proved +much more difficult to track numerically until 2005. That year, computational +breakthroughs were made using a generalized harmonic formulation~\cite{Pretorius:2005gq} and then a ``moving puncture'' approach \cite{Campanelli:2005dd, Baker:2005vv} in the BSSN (Baumgarte-Shapiro-Shibata-Nakamura) formalism~\cite{Shibata:1995we,Baumgarte:1998te} that allowed for the first stable long-term evolutions of moving single and multiple BH systems. These results quickly transformed the field -with the ability to effectively evolve the Einstein field equations +which was now able to effectively evolve the Einstein field equations for coalescing BH-BH binaries and other systems containing moving BHs, including merging BH-NS binaries.

-These breakthroughs have led to many advancements with direct relevance -to astrophysics, including exciting new results on recoil velocities +These breakthroughs had direct relevance +to astrophysics, and enabled exciting new results on recoil velocities from BH-BH mergers~(e.g, \cite{Baker:2006vn,Campanelli:2007ew,HolleyBockelmann:2007eh, Pollney:2007ss,Lousto:2007db,Lousto:2008dn} and references therein), @@ -193,37 +191,42 @@ Pfeiffer:2007yz,Stephens:2011as}.

Meanwhile, general relativistic magneto-hydrodynamics (GRMHD) -on fixed background spacetimes has been implemented in multi-dimensional +on fixed background spacetimes has been successful in multi-dimensional settings since the mid-1990s, focusing on BH accretion processes and relativistic jet production and evolution (see~\cite{Font:2008aa} for a review of the numerical formalism and~\cite{Hawley2009apss} for a review of work on disk and jet models). GRMHD coupled with curvature evolution, on the other hand, which is crucial for modeling large-scale bulk -dynamics in compact binary or single-star collapse scenarios, has +dynamics in compact binary star coalescence or single-star collapse scenarios, has started to produce astrophysically interesting results only in the -past $\sim 3-5$ years, enabled primarily by the availability of the long-term -stable curvature evolution systems discussed above as well as improved GRMHD +past $\sim 3-5$ years, enabled primarily by the availability of long-term +stable curvature evolution systems as well as improved GRMHD algorithms~(see~\cite{Font:2008aa} for a review). In addition to these developments, substantial progress has been made -using physically motivated equations of state (EOS), +in importing more physically motivated equations of state (EOS), including tabulated versions (e.g.,~\cite{Pandharipande:1989hn, Douchin:2001sv,Akmal:1998cf}) and temperature-dependent models -(e.g.,~\cite{Shen:1998by,Shen:1998gq,Lattimer:1991nc}). Some codes also -incorporate microphysical effects, such as neutrino cooling -\cite{Sekiguchi:2011zd}. +(e.g.,~\cite{Shen:1998by,Shen:1998gq,Lattimer:1991nc}). Some codes +have also begun to incorporate microphysical effects of neutrino emission +and deleptonization~\cite{Sekiguchi:2011zd,O'Connor:2009vw}.

Many of the successful techniques used to evolve BH-BH binaries have proven to be equally applicable to merging NS-NS and BH-NS binaries (see, e.g.,~\cite{Faber:2009zz,Duez:2009yz} for reviews), allowing for further investigations into the former and the first full GR simulations of the latter. All recent results use -either the GHG formalism (Caltech/Cornell, LSU/BYU/LIU, and Princeton) or -BSSN ``moving puncture'' gauge (or variants thereof; AEI/Sissa, Illinois, -Jena, and Tokyo/Kyoto). Nearly all include some form of adaptive mesh +either the general harmonic formalism or the +BSSN formalism in the ``moving puncture'' gauge. Nearly all include some form of adaptive mesh refinement, since unigrid models cannot produce accurate long-term evolutions without requiring exorbitant computational resources. Many groups' codes now include GRMHD (used widely for NS-NS mergers, and for BH-NS mergers -in~\cite{Chawla:2010sw}, and some include microphysical effects as well. +in~\cite{Chawla:2010sw}, and some include microphysical effects as +well~(e.g.,\cite{Duez:2009yy,Sekiguchi:2011zd}). +\todo{CDO: I think we should +get completely rid of this; it's impossible to get it right and +misleading. For example, there is the spec guys and me at Caltech; +there is Burrows and Pretorius at Princeton, there is now CITA and +WSU etc. Not at all a good idea to put this in writing.} The groups that have reported simulations of NS-NS or BH-NS mergers include: \begin{itemize} \item {\bf AEI/Sissa}: BH-NS mergers using GRHD~\cite{Loffler:2006nu} and NS-NS