Plasmas quirais com aplicações em efeitos ópticos, conversão áxion-fóton e em cenários astrofísicos

Abstract

In this work, we discuss the propagation of electromagnetic waves in cold chiral plasmas within the framework of the Maxwell-Carroll-Field-Jackiw (MCFJ) theory and bi-isotropic constitutive relations. We initiate by reviewing the essential aspects of electromagnetic wave propagation in plasmas, analyzing

dispersion relations, refractive indices, propagation modes, birefringence effects, and low-frequency he- licon modes. Next, we revisit fundamental aspects of chiral media, whose properties are effectively ruled

by axion electrodynamics, which is also connected to Carroll-Field-Jackiw (CFJ) electrodynamics. Dis- crete symmetries and the corresponding equations of motion associated with these theories are also exa- mined. We then analyze wave propagation parallel to an external magnetic field, considering the timelike

and spacelike components of the CFJ term, which play the role of anomalous chiral conductivities. Modi- fied electromagnetic modes and refractive indices are derived and associated with right- and left-handed

circularly polarized waves. For each refractive index, propagation and absorption regions are illustrated

for selected parameter values. In the low-frequency regime, modified helicon modes with right- and left- handed circular polarizations are obtained, exhibiting behaviors distinct from the conventional helicon.

Optical properties are further investigated through the rotatory power (RP) and the dichroism coeffici- ent. A reversal of the RP sign is observed, an uncommon feature in magnetized plasmas but previously

reported in rotating systems. The same analysis is performed for plasmas described by bi-isotropic cons- titutive relations, where the emergence of a double RP reversal is highlighted. Data from dispersion and

birefringence measurements of radio signals emitted by pulsars and Fast-Radio-Bursts (FRBs) are used

to impose constraints on the chiral parameters. These constraints are tabulated and compared with previ- ously established results in the literature. Chiral effects in rotating plasmas are also analyzed, particularly

birefringence, for which a reversal of PR is again observed. Finally, photon-axion conversion in a chiral plasma is proposed and investigated, highlighting the selectivity of the chiral medium toward photons with a specific circular polarization and enabling resonant conversion between axions and either RCP or LCP photons.