Causality of the Einstein-Israel-Stewart Theory with Bulk Viscosity

Fábio S. Bemfica, Marcelo M. Disconzi, Jorge Noronha

Research output: Contribution to journalArticlepeer-review


We prove that Einstein's equations coupled to equations of the Israel-Stewart-type, describing the dynamics of a relativistic fluid with bulk viscosity and nonzero baryon charge (without shear viscosity or baryon diffusion) dynamically coupled to gravity, are causal in the full nonlinear regime. We also show that these equations can be written as a first-order symmetric hyperbolic system, implying local existence and uniqueness of solutions to the equations of motion. We use an arbitrary equation of state and do not make any simplifying symmetry or near-equilibrium assumption, requiring only physically natural conditions on the fields. These results pave the way for the inclusion of bulk viscosity effects in simulations of gravitational-wave signals coming from neutron star mergers.

Original languageEnglish (US)
Article number221602
JournalPhysical review letters
Issue number22
StatePublished - Jun 7 2019
Externally publishedYes

ASJC Scopus subject areas

  • Physics and Astronomy(all)


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