SHOCKFIND - an algorithm to identify magnetohydrodynamic shock waves in turbulent clouds

Andrew Lehmann*, Christoph Federrath, Mark Wardle

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

6 Citations (Scopus)


The formation of stars occurs in the dense molecular cloud phase of the interstellar medium. Observations and numerical simulations of molecular clouds have shown that supersonic magnetized turbulence plays a key role for the formation of stars. Simulations have also shown that a large fraction of the turbulent energy dissipates in shock waves. The three families of MHD shocks - fast, intermediate and slow - distinctly compress and heat up the molecular gas, and so provide an important probe of the physical conditions within a turbulent cloud. Here, we introduce the publicly available algorithm, shockfind, to extract and characterize the mixture of shock families in MHD turbulence. The algorithm is applied to a three-dimensional simulation of a magnetized turbulent molecular cloud, and we find that both fast and slow MHD shocks are present in the simulation. We give the first prediction of the mixture of turbulence-driven MHD shock families in this molecular cloud, and present their distinct distributions of sonic and Alfv,nic Mach numbers. Using subgrid one-dimensional models of MHD shocks we estimate that similar to 0.03 per cent of the volume of a typical molecular cloud in the Milky Way will be shock heated above 50 K, at any time during the lifetime of the cloud. We discuss the impact of this shock heating on the dynamical evolution of molecular clouds.

Original languageEnglish
Pages (from-to)1026-1039
Number of pages14
JournalMonthly Notices of the Royal Astronomical Society
Issue number1
Publication statusPublished - 21 Nov 2016


  • MHD
  • shock waves
  • turbulence
  • ISM: clouds
  • ISM: kinematics and dynamics

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