Simulations of coronal type III solar radio bursts: 3. Effects of beam and coronal parameters

Li, Bo; Cairns, Iver H.; Robinson, P. A.

doi:10.1029/2008ja013687

Cited by 32 publications

(41 citation statements)

References 73 publications

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“…magnetic connectivity), so we do not expect all beams with a large electron flux above 25 keV to produce interplanetary type III bursts. The increase in type III flux when the number of electrons above 25 keV is increased was demonstrated numerically by Li et al (2008aLi et al ( , 2009Li et al ( , 2011) using a hot, propagating Maxwellian. They showed that increasing the temperature of the initial Maxwellian beam increases the type III radio flux and increases the bandwidth; the burst starts at higher frequencies and stops at lower frequencies.…”

Section: Interplanetary Bursts and >25 Kev Electronsmentioning

confidence: 99%

“…In recent years, several numerical simulations have been performed to simulate the radio coronal type III emissions from energetic electrons and investigate the effects of beam and coronal parameters on the emission (e.g. Li et al 2008bLi et al , 2009Li et al , 2011Tsiklauri 2011;Li & Cairns 2014;Ratcliffe et al 2014) Since the discovery of type III bursts and the advent of continuous and regular HXR observations, many studies have analysed the relationship between type III bursts and hard X-ray emissions. The first studies of the temporal correlations between metric (coronal) type III bursts and HXRs above 10 keV were achieved by Kane (1972Kane ( , 1981.…”

Section: Introductionmentioning

confidence: 99%

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

Reid

Vilmer

2017

A&A

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Context. 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. Aims. Using events where the coronal radio emission above 100 MHz is exclusively from type III bursts, we revisited some longstanding questions regarding the relation between type III bursts and X-ray flares: 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? Methods. We analysed ten years of data from 2002 to 2011 starting with a selection of coronal type III bursts above 100 MHz. We used X-ray flare information from RHESSI >6 keV to make a list of 321 events that have associated type III bursts and X-ray flares, encompassing at least 28% of the initial sample of type III events. We then examined the timings, intensities, associated GOES class, and whether there was an associated interplanetary radio signature in both radio and X-rays. Results. For our 321 events with radio and X-ray signatures, the X-ray emission at 6 keV usually lasted much longer than the groups of type III bursts at frequencies >100 MHz. The selected events were mostly associated with GOES B and C class flares. 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. The weakness of the correlation is related to the coherent emission mechanism of radio type IIIs which can produce high radio fluxes by low density electron beams. Interplanetary type III bursts (<4 MHz) were observed for 54% of the events. The percentage of association increased when events were observed with 25-50 keV X-rays. A stronger interplanetary association was present when 25-50 keV RHESSI count rates were above 250 counts/s or radio fluxes of around 170 MHz were large (>10 3 SFU), relating to electron beams with more energetic electrons above 25 keV and events where magnetic flux tubes extend into the high corona. We also find that whilst on average type III bursts increase in flux with decreasing frequency, the rate of this increase varies from event to event.

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Section: Interplanetary Bursts and >25 Kev Electronsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

Reid

Vilmer

2017

A&A

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“…The series of papers by Li et al (2008aLi et al ( ,b, 2009 were the first to trace an electron beam from the injection site into the corona and solar wind, and calculate the resulting radio emission fully numerically, rather than by analytical estimates. These simulations have more recently been extended to cover a wider frequency range, and used to explore the effects of the background plasma on the emission.…”

Section: "State Of the Art" Simulationsmentioning

confidence: 99%

A review of solar type III radio bursts

Reid

Ratcliffe

2014

Res. Astron. Astrophys.

339

217

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Solar type III radio bursts are an important diagnostic tool in the understanding of solar accelerated electron beams. They are a signature of propagating beams of nonthermal electrons in the solar atmosphere and the solar system. Consequently, they provide information on electron acceleration and transport, and the conditions of the background ambient plasma they travel through. We review the observational properties of type III bursts with an emphasis on recent results and how each property can help identify attributes of electron beams and the ambient background plasma. We also review some of the theoretical aspects of type III radio bursts and cover a number of numerical efforts that simulate electron beam transport through the solar corona and the heliosphere.

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“…Assuming a type-IIIlike emission mechanism for the small-scale features observed in the MWA data, we arrive at a one-to-one correspondence between their peak frequencies and the electron densities at their heights of production in the solar corona. We assume a 4× Newkirk (1961) density profile in the solar corona in order to translate from electron densities (Li et al 2009) into heights (h) in the solar corona. Having computed ν start , Δν and Δt for every feature, we can also determine a height band (Δh) and a propagation speed (v = Δh/Δt)for every feature.…”

Section: Comparison With Type-iii Burstsmentioning

confidence: 99%

Wavelet-based Characterization of Small-scale Solar Emission Features at Low Radio Frequencies

Suresh

Sharma

Oberoi

et al. 2017

ApJ

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Low radio frequency solar observations using the Murchison Widefield Array have recently revealed the presence of numerous weakshort-livednarrowband emission features, even during moderately quiet solar conditions. These nonthermal features occur at rates of many thousands per hour in the 30.72 MHz observing bandwidth, and hencenecessarily require an automated approach for their detection and characterization. Here, we employ continuous wavelet transform using a mother Ricker wavelet for feature detection from the dynamic spectrum. We establish the efficacy of this approach and present the first statistically robust characterization of the properties of these features. In particular, we examine distributions of their peak flux densities, spectral spans, temporal spans, and peak frequencies. We can reliably detect features weaker than 1 SFU, making them, to the best of our knowledge, the weakest bursts reported in literature. The distribution of their peak flux densities follows a power law with an index of −2.23 in the 12-155 SFU range, implying that they can provide an energetically significant contribution to coronal and chromospheric heating. These features typically last for 1-2 s and possess bandwidths of about 4-5 MHz. Their occurrence rate remains fairly flat in the 140-210 MHz frequency range. At the time resolution of the data, they appear as stationary bursts, exhibiting no perceptible frequency drift. These features also appear to ride on a broadband background continuum, hinting at the likelihood of them being weak type-I bursts.

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Simulations of coronal type III solar radio bursts: 3. Effects of beam and coronal parameters

Cited by 32 publications

References 73 publications

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

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

A review of solar type III radio bursts

Wavelet-based Characterization of Small-scale Solar Emission Features at Low Radio Frequencies

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