Coronal type III radio bursts and their X-ray flare and interplanetary type III counterparts

TL;DR

This study investigates the relationship between coronal and interplanetary type III radio bursts and X-ray flares, revealing correlations between radio flux, X-ray intensity, and interplanetary burst occurrence based on a comprehensive analysis of data from 2002 to 2011.

Contribution

It provides the first statistical comparison of coronal and interplanetary type III bursts with X-ray flares, highlighting their temporal and intensity correlations and conditions for interplanetary burst occurrence.

Findings

Weak correlation between radio flux below 327 MHz and 25-50 keV X-ray intensity.

Interplanetary type III bursts observed in 54% of events, increasing with higher X-ray energies.

X-ray emission at 6 keV lasts longer than type III bursts at frequencies above 100 MHz.

Abstract

Type III bursts and hard X-rays are both produced by flare energetic electron beams. The link between both emissions has been investigated in many previous studies, but no statistical studies have compared both coronal and interplanetary type III bursts with X-ray flares. Using coronal radio events above 100 MHz exclusively from type III bursts, we revisited long-standing questions: Do all coronal type III bursts have X-ray counterparts. What correlation, if any, occurs between radio and X-ray intensities. What X-ray and radio signatures above 100 MHz occur in connection with interplanetary type III bursts below 14 MHz. We analysed data from 2002 to 2011 starting with coronal type III bursts above 100 MHz. We used RHESSI X-ray data greater than 6 keV to make a list of 321 events that have associated type III bursts and X-ray flares, encompassing at least 28 percent of the initial sample of type III events. We examined the timings, intensities, associated GOES class, and any interplanetary radio signature. For our 321 events, the X-ray emission at 6 keV usually lasted longer than type III burst groups at frequencies greater than 100 MHz. A weak correlation was found between the type III radio flux at frequencies below 327 MHz and the X-ray intensity at 25-50 keV, with an absence of events at high X-ray intensity and low type III radio flux. Interplanetary type III bursts less than 14 MHz were observed for 54 percent of the events, increasing when events were observed with 25-50 keV X-rays. A stronger interplanetary association was present when 25-50 keV count rates were above 250 counts per second or 170 MHz fluxes were greater than 1000 SFU, relating to more energetic electrons above 25 keV and events where magnetic flux tubes extend into the high corona. On average type III bursts increase in flux with decreasing frequency, the rate varies from event to event.