Relativistic corrections to collective photon scattering in plasmas

Relativistic corrections to Thomson scattering of photons in plasmas are well known [D. H. Sampson, Ap. J. 129, 734 (1959); J. R. Buchler and W. R. Yueh, Ap. J. 210, 440 (1976) (Ref. 1)]. Here we consider the case when collective effects also have to be taken into account and find the relativistic corrections to collective scattering in plasmas. Collective effects are due to the shielding clouds and are important when the wavelength of the scattering radiation is of the same size or larger than the Debye wavelength. This is the case, for instance, in the solar interior where relativistic corrections to Thomson scattering of photons have recently been taken into account in the calculation of the solar opacity [S. Rose, J. Phys. B: Atom. Molec. Phys. 26, L29 (1993); Iglesias and Rogers, Ap. J. 371, 408 (1991) (Ref. 2)] with the result of a few percent decrease. As an application of our results we show that when the relativistic corrections to collective scattering are included, the decrease in the opacity is 0.2%.