Spatially Resolved Transport Parameters in Solar Flares

Abstract The time profile of solar flare radio emission is often modeled as an injection of energetic particles onto a closed magnetic loop, where they may be trapped by the pinching of field lines and remain for a time before decaying through loss of energy to the background or escaping to the solar surface through the bottom of the loop. These injection, trapping, and precipitation models for energetic particle transport have often been used to explain the characteristics of spatially integrated microwave emissions in solar flares. With the high-cadence imaging spectroscopy capabilities of modern radio instruments, these ideas can be probed with new depth. Radio imaging allows for the selection of particular regions of flares to spatially and temporally isolate individual injections and determine individual decay parameters that could be confused in spatially integrated spectra. Simultaneous spectroscopy allows the fitting of light curves versus frequency for insight into the evolution of the particle energy spectrum and a deeper physical understanding of the decay process. Using currently available time resolution and data quality, injections and decays can be fit simultaneously to the order of 1 s. These considerations motivate the creation of the Pulsed-Injection-Precipitation Decomposition Fitter (PIP_Decomp), which implements an automated method for fitting a series of light curves with injection functions convolved with exponential decays to produce spectrally resolved fit parameters. Herein, PIP_Decomp is introduced and tested by applying it to model flares. Then, PIP_Decomp is used to investigate two relatively simple flares observed by the Expanded Owens Valley Solar Array.