Characterizing the Kelvin-Helmholtz instability in interstellar jets using radiation

We present a new diagnostic method to determine the presence of the Kelvin-Helmholtz instability (KHI) in interstellar jets and measuring its main property, the exponential growth rate, using radiation observable on Earth.

Our findings are based on simulations of the relativistic KHI using the 3D3V particle-in-cell code PIConGPU. With its in-situ computation of the emitted far field radiation, we determined angularly resolved radiation spectra for all billions of particles simulated.

We will explain how measuring the electromagnetic radiation from particle jet allows for identifying the stages of the instability and provides a method to settle the question whether the KHI occurs in astro-physical particle jets or not. By identifying these stages, determining the characteristic growth rate of the KHI becomes possible thus providing quantitative insides to the jet dynamics using only the radiation observed on Earth.