# Release Announcement

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

New arrangements and thorns have been added:

• Proca
• NPScalars_Proca
• ProcaBase
• ProcaEvolve
• Proca_simpleID
• TwoPunctures_KerrProca
• lean_public
• LeanBSSNMoL
• NPScalars
• wvuthorns_diagnostics
• particle_tracerET
• Seed_Magnetic_Fields_BNS
• smallbPoynET
• VolumeIntegrals_GRMHD
• VolumeIntegrals_vacuum

In addition, bug fixes accumulated since the previous release in September 2018 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 codes GRHydro and IllinoisGRMHD. 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 400 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 Proca arrangement has been added: This repository provides the tools to evolve the Einstein-Proca system as first described in https://arxiv.org/abs/1505.00797.
• NPScalars_Proca: Implementation of the spin-1 (electromagnetic) and spin-2 (gravitational) Newman-Penrose scalars
• Proca_simpleID: Create analytic initial data for a non-rotating black hole surrounded by a Proca field with mass mu.
• TwoPunctures_KerrProca: A modified TwoPunctures thorn to construct initial data for a single rotating black hole coupled to a massive vector field.
• The Lean arrangement has been added:
• LeanBSSNMoL: Implementation to evolve Einstein's Equations using the W-version of the BSSN formulation together with the puncture gauge. Also available, in the "new_gauge" branch, is a modified "Gamma-driver" that stabilizes highly rotating black hole spacetimes (adapted from Figueras et al; see: https://arxiv.org/abs/1512.04532).
• NPScalars: Implementation of the spin-2 Newman-Penrose scalars
• The WVU Diagnostics arrangement has been added: These thorns are designed primarily to add useful diagnostics for binary neutron star simulations performed with IllinoisGRMHD.
• NSNS_parameter_files Contains parameter files for magnetized and unmagnetized BNS evolutions.
• Seed_Magnetic_Fields_BNS Extended Seed_Magnetic_Fields thorn for binary neutron stars.
• VolumeIntegrals_GRMHD: GRMHD volume integration thorn, currently depends on IllinoisGRMHD and Carpet. Performs volume integrals on arbitrary "Swiss-cheese"-like topologies, and even interoperates with Carpet to track NS centers of mass.
• VolumeIntegrals_vacuum: Same functionality as VolumeIntegrals_GRMHD, but designed for integration of spacetime quantities. Depends on ML_BSSN and ADMBase for integrands.
• particle_tracerET Solves the ODE \partial_t x^i = v^i for typically thousands of tracer particles, using an RK4 integration atop the current time stepping.
• smallbPoynET Computes b^i, b^2, and three spatial components of Poynting flux. It also computes (-1-u_0), which is useful for tracking unbound matter.
• Ticket tracking system moved to bitbucket: https://bitbucket.org/einsteintoolkit/tickets/
• Subversion infrastructure for thorns is no longer maintained at LSU. Instead, the svn checkout mechanism supported by github.com is used.
• Llama supports tensorweights other than 1.0 or 0.0
• Added EinsteinAnalysis/Hydro_Analysis/Hydro_Analysis_Masses.F90 in order to compute the total baryonic mass and baryonic mass within user defined radii.
• A summary of changes Carpet:
• add support for very large grids where 64bit integer are needed for grid indices and sizes of transfer buffers
• fix how physical_time_per_hour is computed
• add functionality to align interior of grid functions to cache boundaries. This requires changes to Cactus and PUGH as well.
• add a parameter "granularity" to make sure the interior of components is a multiple of N points in each direction
• The version of MPI bundled with the ET is now OpenMPI 1.10.7
• The SystemTopology thorn now supports hwloc 2.0

## How to upgrade from Chien-Shiung Wu (ET_2018_09)

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

## Machine notes

Supported (tested) machines include:

• Default Debian, Ubuntu, Fedora, CentOS, Mint, OpenSUSE and MacOS (MacPorts) installations
• Bluewaters
• Comet
• Golub
• Stampede 2
• Shelob
• 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.

All repositories participating in this release carry a branch ET_2019_03 marking this release. These release branches will be updated if severe errors are found.

The "Proca" Release Team on behalf of the Einstein Toolkit Consortium (2019‐03‐29)

• Steven R. Brandt
• Samuel D. Cupp
• Peter Diener
• Zachariah Etienne
• Roland Haas
• Helvi Witek

Mar, 2019