The Einstein Toolkit: a community computational infrastructure for relativistic astrophysics

Abstract

We describe the Einstein Toolkit, a community-driven, freely accessible computational infrastructure intended for use in numerical relativity, relativistic astrophysics, and other applications. The Toolkit, developed by a collaboration involving researchers from multiple institutions around the world, combines a core set of components needed to simulate astrophysical objects such as black holes, compact objects, and collapsing stars, as well as a full suite of analysis tools. The Einstein Toolkit is currently based on the Cactus Framework for high-performance computing and the Carpet adaptive mesh refinement driver. It implements spacetime evolution via the BSSN evolution system and general-relativistic hydrodynamics in a finite-volume discretization. The toolkit is under continuous development and contains many new code components that have been publicly released for the first time and are described in this article. We discuss the motivation behind the release of the toolkit, the philosophy underlying its development, and the goals of the project. A summary of the implemented numerical techniques is included, as are results of numerical test covering a variety of sample astrophysical problems.

Correlated gravitational wave and neutrino signals from general-relativistic rapidly rotating iron core collapse

“…Our new results are based on a set of full GR simulations with our Zelmani core-collapse simulation package, which is based on the open-source Einstein Toolkit [63,64] and includes deleptonization during collapse and neutrino cooling, heating, and deleptonization after bounce via a three-species energy-averaged neutrino leakage scheme. Our simulations use the finite-temperature microphysical nuclear EOS of Lattimer & Swesty [65] with a choice of the nuclear incompressibility K = 220 MeV, which leads to cold neutron stars broadly consistent with current theoretical and observational neutron star mass and radius constraints (see, e.g., [66][67][68]).…”

General relativistic null-cone evolutions with a high-order scheme

“…We consider radial resolutions N x = [13,17,21,25,29,33,37,41,45,49,65] with appropriately adapted time resolutions. As the resolution is increased, the error drops as expected.…”

“…A prominent result was the first stable dynamical evolution of a black hole spacetime in three spatial dimensions achieved by the Pittsburgh group [11,12]. Since then, the Pittsburgh null code (or PITTNullCode) has become the main building block for current implementations of characteristic extraction used in numerical relativity simulations [1,2,3,4,5], and is now part of the publicly available Einstein Toolkit [13]. The code employs a single-null coordinate system, and is formulated in terms of spin-weighted variables that are related to the original variables defined by Bondi and collaborators [8,9,10].…”

Long gamma ray bursts from binary black holes

“…We use the fifth release of the Einstein Toolkit 1 (Löffler et al 2012) based on the Cactus Computational Toolkit (Goodale et al 2003). The initial data are provided by the TwoPunctrures thorn (Ansorg et al 2004).…”