Effects of distribution structure on predictions of plasma behavior in marginally unstable plasma

Due to low collisionality in space and astrophysical plasmas, distributions of ions and electrons observed by spacecraft exist in a state far from thermodynamic equilibrium.The non-Maxwellian features in these distribution functions can trigger microinstabilities, which likely play a role in some of the largest open questions in solar physics, including coronal heating, heating of the bulk solar wind, and accounting for high-frequency waves observed alongside the Alfvenic turbulent cascade. While there is a tremendous amount of information in the structure of these distribution functions, they are typically only represented by a fit of one or two Maxwellian or bi-Maxwellian distributions. In this work, we examine how the fidelity of the model to the observed distribution function affects our predictions for the stability of the plasma, and how much of the information in the distribution function is needed to accurately predict the behavior of the plasma. To do this, we use marginally stable one-dimensional, electrostatic simulations of the electron two-stream instability. For these simulations, there is significantly better agreement between the behavior of the plasma and the predictions of linear theory when a higher-fidelity representation of the distribution function is used. These electrostatic results will also be extended to the electromagnetic regime and used to compare predictions of linear wave activity with the behavior of the plasma using data from Parker Solar Probe.