Nonlinear interaction of photons and phonons in electron-positron plasmas

TLDR

The electron‑positron plasma is highly plastic, so electromagnetic waves can depress the plasma and imprint structural changes via nonresonant or resonant interactions. The study investigates the nonlinear interaction of electromagnetic waves and acoustic modes in an electron‑positron plasma. The resonant interaction, where the group velocity of EM waves matches the phase velocity of acoustic waves, is analyzed using reductive perturbation theory to derive the system’s basic equations. The theory predicts that nonresonant interaction can cause photon coalescence and collapse of plasma cavities in dimensions ≥ 2, and yields bright, kink, and dark soliton solutions, with implications for cosmological relativistically hot electron‑positron plasmas.

Abstract

Nonlinear interaction of electromagnetic waves and acoustic modes in an electron-positron plasma is investigated. The plasma of electrons and positrons is quite plastic so that the imposition of electromagnetic (em) waves causes depression of the plasma and other structural imprints on it through either the nonresonant or resonant interaction. Our theory shows that the nonresonant interaction can lead to the coalescence of photons and collapse of plasma cavity in higher (\ensuremath{\ge}2) dimensions. The resonant interaction, in which the group velocity of em waves is equal to the phase velocity of acoustic waves, is analyzed and a set of basic equations of the system is derived via the reductive perturbation theory. We find new solutions of solitary types: bright solitons, kink solitons, and dark solitons as the solutions to these equations. An implication of the present theory on astrophysical plasma settings is suggested, including the cosmological relativistically hot electron-positron plasma.