Explicit-implicit scheme for relativistic radiation hydrodynamics

Hiroyuki R. Takahashi, Ken Ohsuga, Yuichiro Sekiguchi, Tsuyoshi Inoue, Kengo Tomida

Research output: Contribution to journalArticlepeer-review

19 Citations (Scopus)


We propose an explicit-implicit scheme for numerically solving special relativistic radiation hydrodynamic equations, which ensures a conservation of total energy and momentum (matter and radiation). In our scheme, zeroth and first moment equations of the radiation transfer equation are numerically solved without employing a flux-limited diffusion approximation. For an hyperbolic term, of which the timescale is the light crossing time when the flow velocity is comparable to the speed of light, is explicitly solved using an approximate Riemann solver. Source terms describing an exchange of energy and momentum between the matter and the radiation via the gas-radiation interaction are implicitly integrated using an iteration method. The implicit scheme allows us to relax the Courant-Friedrichs-Lewy condition in optically thick media, where heating/cooling and scattering timescales could be much shorter than the dynamical timescale. We show that our numerical code can pass test problems of one- and two-dimensional radiation energy transport, and one-dimensional radiation hydrodynamics. Our newly developed scheme could be useful for a number of relativistic astrophysical problems. We also discuss how to extend our explicit-implicit scheme to the relativistic radiation magnetohydrodynamics.

Original languageEnglish
Article number122
JournalAstrophysical Journal
Issue number2
Publication statusPublished - 2013 Feb 20
Externally publishedYes


  • hydrodynamics
  • radiative transfer
  • relativistic processes

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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