Grackle

Grackle is a chemistry and radiative cooling library for astrophysical simulations and models. Grackle has interfaces for C, C++, Fortran, and Python codes and provides:

• two options for primordial chemistry and cooling:

  1. non-equilibrium primordial chemistry network for atomic H, D, and He as well as H₂ and HD, including H₂ formation on dust grains.

  2. tabulated H and He cooling rates calculated with the photo-ionization code, Cloudy.

• tabulated metal cooling rates calculated with Cloudy.

• photo-heating and photo-ionization from two UV backgrounds with optional self-shielding corrections:

  1. Faucher-Giguere et al. (2009).

  2. Haardt & Madau (2012).

• support for user-provided arrays of volumetric and specific heating rates.

The Grackle provides functions to update chemistry species; solve radiative cooling and update internal energy; and calculate cooling time, temperature, pressure, and ratio of specific heats (gamma).

For more information on features, installation, and integration with simulation codes and models, see our online documentation.

Software that uses Grackle

A (non-exhaustive) list of software that provides out-of-the-box support for using Grackle includes:

• ChaNGa

• Cholla

• Enzo

• Enzo-E

• Gamer

• Gasoline

• GIZMO

• Swift

We welcome PRs to add your simulation code to this list. We also welcome the inclusion of python modules that depend on Pygrackle.

Resources

• documentation: https://grackle.readthedocs.io/

• source code repository: https://github.com/grackle-project/grackle

• method paper: Smith et al. (2017)