Incoherent Solar Radio Emission
arXiv:2007.14888
Abstract
Incoherent solar radio radiation comes from the free-free, gyroresonance, and gyrosynchrotron emission mechanisms. Free-free is primarily produced from Coulomb collisions between thermal electrons and ions. Gyroresonance and gyrosynchrotron result from the acceleration of low-energy electrons and mildly relativistic electrons, respectively, in the presence of a magnetic field. In the non-flaring Sun, free-free is the dominant emission mechanism with the exception of regions of strong magnetic fields which emit gyroresonance at microwaves. Due to its ubiquitous presence, free-free emission can be used to probe the non-flaring solar atmosphere above temperature minimum. Gyroresonance opacity depends strongly on the magnetic field strength and orientation; hence it provides a unique tool for the estimation of coronal magnetic fields. Gyrosynchrotron is the primary emission mechanism in flares at frequencies higher than 1-2 GHz and depends on the properties of both the magnetic field and the accelerated electrons, as well as the properties of the ambient plasma. In this paper we discuss in detail the above mechanisms and their diagnostic potential.
arXiv commentFrontiers in Astronomy and Space Sciences, accepted for publication
References in corpus (22)
- High-resolution observations of flare precursors in the low solar atmosphere
- Observing the Sun with Atacama Large Millimeter/submillimeter Array (ALMA): High Resolution Interferometric Imaging
- Cold, tenuous solar flare: acceleration without heating
- Center-to-limb observations of the Sun with ALMA
- Radio Spectral Evolution of an X-ray Poor Impulsive Solar Flare: Implications for Plasma Heating and Electron Acceleration
- Magnetography of Solar Flaring Loops with Microwave Imaging Spectropolarimetry
- Broadband microwave burst produced by electron beams
- The Sun at millimeter wavelengths I. Introduction to ALMA Band 3 observations
- A First Comparison of Millimeter Continuum and Mg II Ultraviolet Line Emission from the Solar Chromosphere
- The Low-Frequency Solar Corona in Circular Polarization
- A Cold Flare With Delayed Heating
- Diffusive Transport of Energetic Electrons in the Solar Corona: X-ray and Radio Diagnostics
- Dynamic Magnetography of Solar Flaring Loops
- Observations of solar chromospheric oscillations at 3 mm with ALMA
- Coronal Magnetography of a Simulated Solar Active Region from Microwave Imaging Spectropolarimetry
- Spatially-resolved Energetic Electron Properties for the 21 May 2004 Flare from Radio Observations and 3D Simulations
- Theory of gyroresonance and free-free emissions from non-Maxwellian quasi-steady-state electron distributions
- Frequency rising sub-THz emission from solar flare ribbons
- Solar Burst Analysis with 3D Loop Models
- Allen Telescope Array Multi-Frequency Observations of the Sun
- Spectral Gradient of the Thermal Millimetre Continuum as a Diagnostic for Optical Thickness in the Solar Atmosphere
- Thyr: A Volumetric Ray-Marching Tool for Simulating Microwave Emission