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The Sixteenth Release of the Einstein Toolkit

We are pleased to announce the sixteenth release (code name “Tesla”) of the Einstein Toolkit, an open, community developed software infrastructure for relativistic astrophysics. The highlights of this release are:

* A new thorn, Hydro_RNSID which models a rotating neutron star.

* Tutorials have been updated and the install process for new users has been simplified.

In addition, bug fixes accumulated since the previous release in June 2017 have been included.

The Einstein Toolkit is a collection of software components and tools for simulating and analyzing general relativistic astrophysical systems that builds on numerous software efforts in the numerical relativity community including CactusEinstein, the Carpet AMR infrastructure and the relativistic magneto-hydrodynamics code GRHydro. For parts of the toolkit, the Cactus Framework is used as the underlying computational infrastructure providing large-scale parallelization, general computational components, and a model for collaborative, portable code development. The toolkit includes modules to build complete codes for simulating black hole spacetimes as well as systems governed by relativistic magneto-hydrodynamics.

The Einstein Toolkit uses a distributed software model and its different modules are developed, distributed, and supported either by the core team of Einstein Toolkit Maintainers, or by individual groups. Where modules are provided by external groups, the Einstein Toolkit Maintainers provide quality control for modules for inclusion in the toolkit and help coordinate support. The Einstein Toolkit Maintainers currently involve postdocs and faculty from six different institutions, and host weekly meetings that are open for anyone to join in.

Guiding principles for the design and implementation of the toolkit include: open, community-driven software development; well thought out and stable interfaces; separation of physics software from computational science infrastructure; provision of complete working production code; training and education for a new generation of researchers.

For more information about using or contributing to the Einstein Toolkit, or to join the Einstein Toolkit Consortium, please visit our web pages at http://einsteintoolkit.org.

The Einstein Toolkit is primarily supported by NSF 1550551/1550461/1550436/1550514 (Einstein Toolkit Community Integration and
Data Exploration).

The Einstein Toolkit contains about 200 regression test cases. On a large portion of the tested machines, almost all of these tests pass, using both MPI and OpenMP parallelization.

The changes between this and the previous release include:

=== Larger changes since last release ===

* The support for generic machines is more robust, and the ET should compile, run, and pass the test suites out of the box on new Linux machines.

* A Jupyter-based Tutorial (https://einsteintoolkit.org/documentation/new-user-tutorial) is now available.

* The AVX512 instruction set used on the Intel “Knight’s Landing” platform is now supported.

* PITTNullCode now has test outputs

* EOS_Omni polytrope supports hybrid equations of date with up to 10 pieces

=== New thorns or tools ===

* The Hydro_RNSID thorn which provides initial data for a rotating neutron star.

=== Upcoming changes for the next releases ===

* New thorns:

* GiRaFFE, which models plasma flows in a dynamic spacetime

* Changes to WVUThorns_Diagnostics

* Seed_Magnetic_Fields-modified: Extended Seed_Magnetic_Fields thorn for binary neutron stars. Supercedes Seed_Magnetic_Fields thorn.
* Meudon_Bin_NS-modified: Modifications to Meudon BNS initial data thorn to disable the overwriting of initial lapse/shift, which acts to significantly reduce coordinate eccentricity. Supercedes Meudon_Bin_NS thorn.
* VolumeIntegrals_GRMHD-new: Performs volume integrals on arbitrary “Swiss-cheese”-like topologies, and even interoperates with Carpet to track NS centers of mass.
* VolumeIntegrals_vacuum-new: Ensures that VI_vacuum can be used without enabling a GRMHD code.
* particle_tracerET-new: Solves the ODE D_t xi = vi for typically thousands of tracer particles, using an RK4 integration atop the current timestepping.
* smallbPoynET-new: Computes b^i, b^2, and three spatial components of Poynting flux. It also computes (-1-u0), which is useful for tracking unbound matter

=== How to upgrade from Hack (ET_2017_06) ===

To upgrade from the previous release, use GetComponents with the new thornlist to check out the new version.

See the Download page (http://einsteintoolkit.org/download/) on the Einstein Toolkit website for download instructions.

=== Machine notes ===

Supported (tested) machines include:

– Default Debian, Ubuntu, Fedora, CentOS, Mint, OpenSUSE and MacOS (Homebrew and MacPorts) installations
– Bluewaters
– Comet
– Cori
– Draco
– Edison
– Golub
– Hydra
– Marconi
– Minerva
– Queenbee 2
– Stampede 2
– SuperMIC
– Wheeler

* TACC machines: defs.local.ini needs to have sourcebasedir = $WORK and basedir = $SCRATCH/simulations configured for this machine. You need to determine $WORK and $SCRATCH by logging in to the machine.

* A new configuration for KNL nodes is being worked on, but not yet included in the release (but compilation works and tests mostly pass).

All repositories participating in this release carry a branch ET_2018_02 marking this release. These release branches will be updated if severe errors are found.

The “Tesla” Release Team on behalf of the Einstein Toolkit Consortium (2018-02-15)

Steven R. Brandt
Peter Diener
Roland Haas
Ian Hinder

Feb, 2018