Four-dimensional structured wavepacket propagation in relativistic and cosmological plasmas*

Four-dimensional (3+1) plasma wavepackets are studied considering relativistic and cosmological background effects. For relativistic electron plasmas, different exact forms of wavepacket propagation are shown to exist in terms of Airy functions. They show accelerated propagations along coordinates transverse to the thermal speed cone coordinate. Similarly, Airy propagation is a solution for relativistic electron plasma waves in the paraxial approximation in time and in space domains. In both different cases, wavepackets remain structured in the transverse plane while they display accelerated propagation, or curved parabolic trajectories [1].

Similarly, for cosmological plasmas, we found (3+1) structured plasma wavepackets that depend on the cosmological scale factor of the Universe [2]. Depending on the content of the Universe (on the equation of the state of the perfect fluid filling it), different forms of plasma propagation can occur. We analyze how cosmological expansion of the Universe determines the form of the structured wavepacket, modifying, for example, its cosmological decay in the hot radiation-dominated era, or its accelerated propagation in a dark energy cosmology.

In both cases, we show how the most general wavepackets can be constructed by using arbitrary spectral functions. These allow us to study a wide family of finite-energy plasma wavepackets.