On the speed and acceleration of electron beams triggering interplanetary type III radio bursts

Abstract

Type III radio bursts are intense radio emissions triggered by beams of energetic electrons often associated with solar flares. These exciter beams propagate outwards from the Sun along an open magnetic field line in the corona and in the interplanetary (IP) medium. We performed a statistical survey of 29 simple and isolated IP type III bursts observed by STEREO/Waves instruments between January 2013 and September 2014. We investigated their time-frequency profiles in order to derive the speed and acceleration of exciter electron beams. We show these beams noticeably decelerate in the IP medium. Obtained speeds range from $\sim$ 0.02c up to $\sim$ 0.35c depending on initial assumptions. It corresponds to electron energies between tens of eV and hundreds of keV, and in order to explain the characteristic energies or speeds of type III electrons ($\sim 0.1$c) observed simultaneously with Langmuir waves at 1 au, the emission of type III bursts near the peak should be predominately at double plasma frequency. Derived properties of electron beams can be used as input parameters for computer simulations of interactions between the beam and the plasma in the IP medium.

References in corpus (4)

• Dynamics of electron beams in the inhomogeneous solar corona plasma
• Evolution of the Solar Flare Energetic Electrons in the Inhomogeneous Inner Heliosphere
• Statistical Survey of Type III Radio Bursts at Long Wavelengths Observed by the Solar TErrestrial RElations Observatory (STEREO)/Waves Instruments: Radio Flux Density Variations with Frequency
• Statistical Survey of Type III Radio Bursts at Long Wavelengths Observed by the Solar TErrestrial RElations Observatory (STEREO)/Waves Instruments: Goniopolarimetric Properties and Radio Source Locations

Cited by in corpus (15)

• Imaging Spectroscopy of Solar Radio Burst Fine Structures
• Density Fluctuations in the Solar Wind Based on Type III Radio Bursts Observed by Parker Solar Probe
• Observations of solar X-ray and EUV jets and their related phenomena
• A type III radio burst automatic analysis system and statistic results for a half solar-cycle with the Nançay Decameter Array data
• Imaging Spectroscopy of Type U and J Solar Radio Bursts with LOFAR
• Solar type III radio burst time characteristics at LOFAR frequencies and the implications for electron beam transport
• Densities Probed by Coronal Type III Radio Burst Imaging
• Langmuir Wave Electric Fields Induced by Electron Beams in the Heliosphere
• Using radio triangulation to understand the origin of two subsequent type II radio bursts
• Spatial expansion and speeds of type III electron beam sources in the solar corona
• An analysis of interplanetary solar radio emissions associated with a coronal mass ejection
• Small electron acceleration episodes in the solar corona
• Solar Type U Burst Associated with a High Coronal Loop
• Forward Modeling of the Type III Radio Burst Exciter
• Coronal electron density: Insights from radio and in situ observations, and EUHFORIA modeling