Langmuir waves associated with magnetic holes in the solar wind

Langmuir waves (electrostatic waves near the electron plasma frequency) are often observed in the solar wind and could play a role in the energy dissipation of electrons. The largest amplitude Langmuir waves are typically associated with type II and III solar radio bursts and interplanetary foreshocks. In addition, Langmuir waves occur in the pristine solar wind, but their source is not well understood. Langmuir waves have been observed inside isolated magnetic holes suggesting that magnetic holes play an important role in the generation of these waves. We provide a statistical analysis of the Langmuir waves' occurrence in the solar wind at different heliocentric distances. In particular, we investigate the relationship between magnetic holes and Langmuir waves in the solar wind. We use Solar Orbiter’s Radio and Plasma Waves (RPW) and Magnetometer (MAG) instruments. From RPW we use electric field waveform and onboard statistical data (STAT) from the Time Domain Sampler (TDS) to identify Langmuir waves and investigate their properties. We use the spacecraft’s potential to estimate plasma density. MAG data is used to measure the background magnetic field and detect magnetic holes. The statistical analysis is performed over 2020-2021. We observe that Langmuir waves are more likely to occur inside magnetic holes than in the pristine solar wind. We also confirm the local formation of Langmuir waves inside magnetic holes and that these waves are, typically, of low amplitude.