Dispersion relations of relativistic radiation hydrodynamics

• Published in: Astrophysics and space science Vol. 370; no. 1; p. 4
• Main Author: Gavassino, Lorenzo
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Netherlands 01.01.2025; Springer Nature B.V
• Subjects: Astrobiology; Astronomy; Astrophysics; Astrophysics and Astroparticles; Cosmology; Damping; Dispersion; Energy; Equilibrium; Flow velocity; Fluid mechanics; Heat; Heat waves; Hydrodynamics; Observations and Techniques; Physics; Physics and Astronomy; Radiation; Radiation absorption; Relativistic effects; Sound transmission; Sound waves; Space Exploration and Astronautics; Space Sciences (including Extraterrestrial Physics; Theory of relativity; Heat conduction; Viscosity; Radiation hydrodynamics; Wave propagation; Causality
• ISSN: 0004-640X; 1572-946X
• DOI: 10.1007/s10509-025-04395-x

We compute the linearised dispersion relations of shear waves, heat waves, and sound waves in relativistic “matter+radiation” fluids with grey absorption opacities. This is done by solving radiation hydrodynamics perturbatively in the ratio “radiation stress-energy”/“matter stress-energy”. The resulting expressions ω = ω ( k ) accurately describe the hydrodynamic evolution for any k ∈ R . General features of the dynamics (e.g., covariant stability, propagation speeds, and damping of discontinuities) are argued directly from the analytic form of these dispersion relations.