Survey on solar X-ray flares and associated coherent radio emissions

Abstract

The radio emission during 201 X-ray selected solar flares was surveyed from 100 MHz to 4 GHz with the Phoenix-2 spectrometer of ETH Zurich. The selection includes all RHESSI flares larger than C5.0 jointly observed from launch until June 30, 2003. Detailed association rates of radio emission during X-ray flares are reported. In the decimeter wavelength range, type III bursts and the genuinely decimetric emissions (pulsations, continua, and narrowband spikes) were found equally frequently. Both occur predominantly in the peak phase of hard X-ray (HXR) emission, but are less in tune with HXRs than the high-frequency continuum exceeding 4 GHz, attributed to gyrosynchrotron radiation. In 10% of the HXR flares, an intense radiation of the above genuine decimetric types followed in the decay phase or later. Classic meter-wave type III bursts are associated in 33% of all HXR flares, but only in 4% they are the exclusive radio emission. Noise storms were the only radio emission in 5% of the HXR flares, some of them with extended duration. Despite the spatial association (same active region), the noise storm variations are found to be only loosely correlated in time with the X-ray flux. In a surprising 17% of the HXR flares, no coherent radio emission was found in the extremely broad band surveyed. The association but loose correlation between HXR and coherent radio emission is interpreted by multiple reconnection sites connected by common field lines.

arXiv commentSolar Physics, in press

References in corpus (1)

• Solar flare radio pulsations as a signature of dynamic magnetic reconnection

Cited by in corpus (27)

• An Observational Overview of Solar Flares
• A Review of Solar Type III Radio Bursts
• Recent Advances in Understanding Particle Acceleration Processes in Solar Flares
• The Relationship Between Solar Radio and Hard X-ray Emission
• Broadband Quasi-Periodic Radio and X-ray Pulsations in a Solar Flare
• Characteristics of the flare acceleration region derived from simultaneous hard X-ray and radio observations
• Type III Solar Radio Burst Source Region Splitting Due to a Quasi-Separatrix Layer
• The Low-High-Low Trend of Type III Radio Burst Starting Frequencies and Solar Flare Hard X-rays
• Densities Probed by Coronal Type III Radio Burst Imaging
• Modeling of gyrosynchrotron radio emission pulsations produced by MHD loop oscillations in solar flares
• The spectral difference between solar flare HXR coronal and footpoint sources due to wave-particle interactions
• Particle Acceleration In Plasmoid Ejections Derived From Radio Drifting Pulsating Structures
• Flare-associated type III radio bursts and dynamics of the EUV jet from SDO/AIA and RHESSI observations
• Diagnostics of non-thermal distributions in solar flare spectra observed by RESIK and RHESSI
• Coronal type III radio bursts and their X-ray flare and interplanetary type III counterparts
• Radio Spectral Imaging of an M8.4 Eruptive Solar Flare: Possible Evidence of a Termination Shock
• Simultaneous X-ray and radio observations of Young Stellar Objects in NGC 1333 and IC 348
• Are there Radio-quiet Solar Flares?
• Location of Decimetric Pulsations in Solar Flares
• A tiny event producing an interplanetary type III burst
• Multiwavelength study of a Solar Eruption from AR NOAA 11112 I. Flux Emergence, Sunspot Rotation and Triggering of a Solar Flare
• Statistical analysis of circular-ribbon flares
• Fitting FFT-derived Spectra: Theory, Tool, and Application to Solar Radio Spike Decomposition
• Gyrokinetic electron acceleration in the force-free corona with anomalous resistivity
• Astrophysics in 2005
• Preparing for Solar and Heliospheric Science with the SKAO: An Indian Perspective
• Bursty acceleration and 3D trajectories of electrons in a solar flare