User: jfaber
Date: 2011/11/11 03:06 PM
Modified:
/
ET.tex
Log:
Reworked list of NSNS and BHNS refs by topic, not by group
per Christian's suggestion
Moved scientific developments yet to occur from
Sec. 2.1 into conclusions, might need to be trimmed a bit
File Changes:
Directory: /
============
File [modified]: ET.tex
Delta lines: +71 -106
===================================================================
--- ET.tex 2011-11-11 16:18:21 UTC (rev 186)
+++ ET.tex 2011-11-11 21:06:36 UTC (rev 187)
@@ -213,42 +213,19 @@
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
+NS-NS \cite{Anderson:2007kz,Anderson:2008zp,Baiotti:2008ra,Baiotti:2009gk,Baiotti:2010xh,
+Baiotti:2011am,Bernuzzi:2011aq,Giacomazzo:2009mp,
+Giacomazzo:2010bx,Gold:2011df,Hotokezaka:2011dh,Kiuchi:2009jt, Kiuchi:2010ze,Liu:2008xy,Rezzolla:2010fd,Rezzolla:2011da,Sekiguchi:2011zd,Sekiguchi:2011mc,Thierfelder:2011yi,Yamamoto:2008js} and BH-NS \cite{Chawla:2010sw,Duez:2008rb,Duez:2009yy,Etienne:2007jg,Etienne:2008re,Foucart:2010eq,Foucart:2011mz,Kyutoku:2010zd,Kyutoku:2011vz,Lackey:2011vz,Loffler:2006nu,Shibata:2006bs,
+Shibata:2006ks,Shibata:2007zm,Shibata:2009cn,
+Shibata:2010zz,Stephens:2011as,Yamamoto:2008js} binaries (for reviews, see also~\cite{Faber:2009zz,Duez:2009yz}), allowing for further investigations into the former
and the first full GR simulations of the latter. All recent results use
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
+without requiring exorbitant computational resources, though some BH-NS simulations have been performed with a pseudospectral code \cite{Duez:2008rb,Duez:2009yy,Foucart:2010eq,Foucart:2011mz}. 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~(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
-mergers using GRHD~\cite{Baiotti:2008ra,Baiotti:2009gk,Baiotti:2010xh,
-Baiotti:2011am,Rezzolla:2010fd} and GRMHD~\cite{Giacomazzo:2009mp,
-Giacomazzo:2010bx,Rezzolla:2011da}.
-\item {\bf Caltech/Cornell}: A {\em pseudospectral}, GRHD code has been used
-to simulate BH-NS mergers~\cite{Duez:2008rb,Duez:2009yy,Foucart:2010eq}.
-\item {\bf Illinois}: BH-NS mergers using GRHD~\cite{Etienne:2007jg,Etienne:2008re}
-and NS-NS mergers using GRMHD~\cite{Liu:2008xy}.
-\item {\bf Jena}: NS-NS mergers using GRHD~\cite{Thierfelder:2011yi}.
-\item {\bf LSU/BYU/LIU}: BH-NS mergers using GRMHD~\cite{Chawla:2010sw} and
-NS-NS mergers using GRHD~\cite{Anderson:2007kz}
-and GRMHD~\cite{Anderson:2008zp}.
-\item {\bf Princeton}: BH-NS mergers using GRHD~\cite{Stephens:2011as}.
-\item {\bf Tokyo/Kyoto}: BH-NS mergers using GRHD~\cite{Shibata:2006bs,
-Shibata:2006ks,Shibata:2007zm,Yamamoto:2008js,Shibata:2009cn,
-Kyutoku:2010zd,Shibata:2010zz} and NS-NS mergers using GRHD
-\cite{Yamamoto:2008js,Kiuchi:2009jt, Kiuchi:2010ze,Hotokezaka:2011dh},
-most recently with the inclusion of neutrino cooling~\cite{Sekiguchi:2011zd}.
-\todo{Check for updates to list before submission!}
-\end{itemize}
+well~(e.g.,\cite{Duez:2009yy,Sekiguchi:2011zd,Sekiguchi:2011mc}).
In addition to studying binary mergers, numerical relativity is a necessary
element for understanding stellar collapse and dynamical instabilities
@@ -261,7 +238,7 @@
rapidly rotating polytropic NS models~\cite{Shibata:1999yx,Baiotti:2006wn,
Manca:2007ca}.
-Simultanious to the advances in both our physical understanding of
+Simultaneously with the advances in both our physical understanding of
relativistic dynamics and the numerical techniques required to study them,
a set of computational tools and libraries has been developed with the
aim of providing a computational core that can enable new science,
@@ -299,80 +276,17 @@
One of the aims of the Einstein Toolkit is to provide or extend
some of these missing ingredients in the course of its development.
-The three most important of all possible additions, as deemed by
-the Einstein Toolkit members, are listed below:
+Over the past three years, routines have been added to the code to allow for a wider range of initial data choices,
+to allow for multithreading in hydrodynamic evolutions, and to refine the {\tt Carpet} adaptive mesh refinement
+driver. Looking forward,
+three possible additions to future releases are the inclusion of magnetic fields
+into the dynamics via an ideal MHD treatment, more physical nuclear matter
+equations of state (EOSs) including the ability to model finite-temperature effects,
+and higher-order numerical techniques. All of these are under active development,
+with MHD and finite-temperature evolution code already available, though not completely
+documented, within the public toolkit releases, and will be made available once they are
+thoroughly tested and validated against known results.
-\begin{itemize}
- \item{\bf MHD}. Many studies, in particular those concerned with
- massive star collapse, NS-NS or BH-NS binaries and rotational
- non-axisymmetric instabilities, are still performed in pure GRHD\@.
- Without a doubt, these systems must be simulated with GRMHD to capture
- the effects of magnetic fields which in many cases will
- alter the simulation outcome on a qualitative level and may be
- the driving mechanisms behind much of the observable EM signature
- from GRBs (e.g.,~\cite{Woosley:2006fn})
- and magneto-rotationally exploding core-collapse supernovae
- (e.g.,~\cite{Burrows:2007yx}). In addition, all simulations that have
- taken magnetic fields into account are still limited to the
- ideal MHD approximation, which assumes perfect conductivity.
- Non-ideal GRMHD schemes are just becoming
- available~(see, e.g.,~\cite{Palenzuela:2008sf,DelZanna:2007pk}),
- but have yet to be implemented widely in many branches of numerical relativity.
-
- \item {\bf Equation of state (EOS), microphysics, and radiation
- transport}. Most presently published 3D GR(M)HD simulations, with the
- exception of recent work on massive star collapse
- (see, e.g.,~\cite{Ott:2006eu}) and binary mergers
- (see, e.g.,~\cite{Sekiguchi:2011zd}),
- relied on simple zero-temperature descriptions of
- NS stellar structure, with many assuming simple polytropic forms.
- Such EOSs are computationally
- efficient, but are not necessarily a good description for matter in
- relativistic astrophysical systems. The inclusion of
- finite-temperature EOSs, derived from the microphysical descriptions of
- high-density matter, will lead to qualitatively different and much
- more astrophysically reliable results (see, e.g.,~\cite{Ott:2006eu}).
- In addition, most GR(M)HD studies
- neglect transport of neutrinos and photons
- and their interactions with matter. Neutrinos in
- particular play a crucial role in core-collapse supernovae and in
- the cooling of NS-NS merger remnants, thus they must not be left out when
- attempting to accurately model such events. Few studies have
- incorporated neutrino and/or photon transport and interactions in
- approximate ways (see, e.g.,~\cite{Ott:2006eu,Farris:2008fe,Sekiguchi:2011zd}).
-
- \item {\bf High-order schemes and AMR\@}. Numerical accuracy is a
- central issue in long-term GR(M)HD simulations and must be addressed
- by a combination of (1) adaptive mesh refinement (AMR), which is used to focus
- grid points on regions where finer resolution is needed, and (2)
- high-order numerical techniques.
-
-Several AMR codes, including the {\tt Carpet} driver~\cite{CarpetCode:web}
-included in the Einstein Toolkit,
-are publicly available. An important task going forward is
- to facilitate the coupling of existing and future GRMHD codes
- with AMR to avoid under-resolving the
- dynamics in the systems under investigation. AMR methods are
- often much more complicated than uniformly distributed
- mesh methods, and require sophisticated algorithms to make use of
- massively parallel systems efficiently.
-
- While AMR can increase resolution near regions of interest within
- the computational domain, it does not increase the convergence
- order of the underlying numerical methods. Simulations of BHs
- can easily make use of high-order numerical methods, with eighth-order
- convergence commonly seen at present. However,
- most GRMHD schemes, while implementing high-resolution
- shock-capturing methods,
- are still limited to 2nd-order numerical accuracy in the
- hydrodynamic/MHD sector while performing
- curvature evolution with 4th-order accuracy or more. Higher order
- GRMHD schemes are in use in fixed-background simulations
- (e.g.,~\cite{Tchekhovskoy:2007zn}), but still await implementation in
- fully dynamical simulations.
-\end{itemize}
-
-
\subsection{Academic and Social}
A primary concern for research groups is securing reliable funding
@@ -2901,8 +2815,8 @@
\label{fig:kasner}}
\end{figure}
-
\section{Conclusion and Future Work}
+
In this article, we described the Einstein Toolkit, a collection
of freely available and easy-to-use computational codes for numerical
relativity and relativistic astrophysics. The code details and example
@@ -2924,8 +2838,45 @@
neutrinos, and photons will be necessary and will need to be matched
by improvements in infrastructure (e.g., more flexible AMR on general
grids) and computing hardware for the required fully coupled 3-D,
-multi-scale, multi-physics simulations to become reality.
+multi-scale, multi-physics simulations to become reality. These tasks,
+as well as the others mentioned below, are likely to occupy a great deal of the
+effort spent developing future versions of the Einstein Toolkit over the next few years.
+ Without a doubt, collapsing stars and merging BH-NS and NS-NS binaries must be simulated with GRMHD to capture
+ the effects of magnetic fields that in many cases will
+ alter the simulation outcome on a qualitative level and may be
+ the driving mechanisms behind much of the observable EM signature
+ from GRBs (e.g.,~\cite{Woosley:2006fn})
+ and magneto-rotationally exploding core-collapse supernovae
+ (e.g.,~\cite{Burrows:2007yx}). To date, all simulations that have
+ taken magnetic fields into account are still limited to the
+ ideal MHD approximation, which assumes perfect conductivity.
+ Non-ideal GRMHD schemes are just becoming
+ available~(see, e.g.,~\cite{Palenzuela:2008sf,DelZanna:2007pk}),
+ but have yet to be implemented widely in many branches of numerical relativity.
+
+ Most presently published 3D GR(M)HD simulations, with the
+ exception of recent work on massive star collapse
+ (see, e.g.,~\cite{Ott:2006eu}) and binary mergers
+ (see, e.g.,~\cite{Sekiguchi:2011zd}),
+ relied on simple zero-temperature descriptions of
+ NS stellar structure, with many assuming simple polytropic forms.
+ Such EOSs are computationally
+ efficient, but are not necessarily a good description for matter in
+ relativistic astrophysical systems. The inclusion of
+ finite-temperature EOSs, derived from the microphysical descriptions of
+ high-density matter, will lead to qualitatively different and much
+ more astrophysically reliable results (see, e.g.,~\cite{Ott:2006eu}).
+ In addition, most GR(M)HD studies
+ neglect transport of neutrinos and photons
+ and their interactions with matter. Neutrinos in
+ particular play a crucial role in core-collapse supernovae and in
+ the cooling of NS-NS merger remnants, thus they must not be left out when
+ attempting to accurately model such events. Few studies have
+ incorporated neutrino and/or photon transport and interactions in
+ approximate ways (see, e.g.,~\cite{Ott:2006eu,Farris:2008fe,Sekiguchi:2011zd,Sekiguchi:2011mc}).
+
+
%%% One of the desirable additions of physics is a proper treatment of
%%% radiation, in particular neutrinos. Another desirable addition would be some
%%% approximation of emission of electro-magnetic waves. Radiation transport is,
@@ -2957,6 +2908,20 @@
cell-centered AMR, refluxing, and GRMHD is underway and will be
reported in a future publication.
+ While AMR can increase resolution near regions of interest within
+ the computational domain, it does not increase the convergence
+ order of the underlying numerical methods. Simulations of BHs
+ can easily make use of high-order numerical methods, with eighth-order
+ convergence commonly seen at present. However,
+ most GRMHD schemes, while implementing high-resolution
+ shock-capturing methods,
+ are still limited to 2nd-order numerical accuracy in the
+ hydrodynamic/MHD sector while performing
+ curvature evolution with 4th-order accuracy or more. Higher order
+ GRMHD schemes are in use in fixed-background simulations
+ (e.g.,~\cite{Tchekhovskoy:2007zn}), but still await implementation in
+ fully dynamical simulations.
+
%%% CDO: We have not even talked about the current MHD implementation,
%%% how can we talk about its improvement?
%%%
