Simulating radio emissions from particle showers in complex media with CORSIKA 8

CORSIKA 8 is a modern Monte-Carlo simulation framework for particle showers in air and dense media. The calculation of shower-induced radio-emissions is a key element of the code, relevant for experiments targeting radio detection of cosmic rays and neutrinos, among others. In this contribution, we report on the unique capabilities of CORSIKA 8 to simulate the radio emission from showers developing in inhomogeneous media and the propagation of this radiation through these complex environments that cannot be properly treated with other methods. Several radio emission and propagation algorithms are provided by the framework, including the Endpoint and ZHS formalisms, numerical raytracing, and a new Green's function-based approach for a full-electrodynamics signal calculation provided by the Eisvogel package. We briefly review these approaches and show simulation results relevant for radio neutrino experiments operating in the Arctic and Antarctic, including the modeling of in-ice particle cascades and the characterization of the physics background arising from cosmic-ray air shower cores impacting the ice sheet.