Radio Submillimeter and γ‐Ray Observations of the 2003 October 28 Solar Flare

Trottet, G.; Krucker, S.; Lüthi, T.; Magun, A.

doi:10.1086/528787

Cited by 45 publications

(64 citation statements)

References 29 publications

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“…Figure 4 shows that the optically-thin part of the observed radio spectrum is emitted by electrons in the ∼ 800 to 7,000-10,000 keV energy range, that is above the break energy of the electron spectrum deduced from the HXR/GR photon spectrum. This is consistent with earlier findings (Trottet et al, 1998(Trottet et al, , 2000(Trottet et al, , 2008. B and T trap , which fix the value of N R , are not independent parameters in the data fitting process.…”

Section: Relationship Between Radio and Hxr/gr Emitting Electrons Dursupporting

confidence: 92%

Origin of the 30 THz Emission Detected During the Solar Flare on 2012 March 13 at 17:20 UT

et al. 2015

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Solar observations in the infrared domain can bring important clues on the response of the low solar atmosphere to primary energy released during flares. At present the infrared continuum has been detected at 30 THz (10 µm) in only a few flares. SOL2012-03-13 , which is one of these flares, has been presented and discussed in Kaufmann et al. (2013). No firm conclusions were drawn on the origin of the mid-infrared radiation. In this work we present a detailed multi-frequency analysis of the SOL2012-03-13 event, including observations at radio millimeter and sub-millimeter wavelengths, in hard X-rays (HXR), gamma-rays (GR), Hα, and white-light. HXR/GR spectral analysis shows that SOL2012-03-13 is a GR line flare and allows estimating the numbers of and energy contents in electrons, protons and α particles produced during the flare. The energy spectrum of the electrons producing the HXR/GR continuum is consistent with a broken power-law with an energy break at ∼ 800 keV. It is shown that the high-energy part (above ∼ 800 keV) of this distribution is responsible for the high-frequency radio emission (> 20 GHz) time-independent models of the quiet and flare atmospheres, we find that most (∼80%) of the observed 30 THz radiation can be attributed to thermal freefree emission of an optically-thin source. Using the F2 flare atmospheric model (Machado et al., 1980) this thin source is found to be at temperatures T ∼ 8000 K and is located well above the minimum temperature region. We argue that the chromospheric heating, which results in 80 % of the 30 THz excess radiation, can be due to energy deposition by non-thermal flare accelerated electrons, protons and α particles. The remaining 20% of the 30 THz excess emission is found to be radiated from an optically-thick atmospheric layer at T ∼ 5000 K, below the temperature minimum region, where direct heating by non-thermal particles is insufficient to account for the observed infrared radiation.

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Section: Relationship Between Radio and Hxr/gr Emitting Electrons Dursupporting

confidence: 92%

Origin of the 30 THz Emission Detected During the Solar Flare on 2012 March 13 at 17:20 UT

et al. 2015

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“…From desirable to have the hard X-ray spectral index at energies up to several hundred keV when making this comparison. Previously, such comparisons between microwave and HXR/γ-ray photon spectra up to several hundreds of keV have been possible with GRANAT/PHEBUS data (Trottet et al 1998;Vilmer et al 1999). Those studies found consistency between the spectral indices of the radio-emitting electrons and the HXR/γ-ray-emitting electrons at energies above several hundred keV.…”

Section: Physical Properties Of Flare-accelerated Particles From Hardmentioning

confidence: 96%

“…One can envisage a source of ultra-relativistic leptons in a very high magnetic field region: Trottet et al (2008) suggest that ultra-relativistic positrons resulting from pion decay are a possible source of the impulsive submillimeter component in SOL2003-10-28T11:10 (X17.2) seen in conjunction with highenergy protons (>200 MeV), although it seems unlikely that sufficient positrons can be produced by this means and energetic electrons are still a more plausible interpretation. An optically-thick thermal source could produce a rising spectrum, but it would have to be either exceptionally large or exceptionally hot (e.g., Silva et al 2007, who prefer an interpretation in terms of gyrosynchrotron emission from electrons in a very strong magnetic field).…”

Section: Sol2002-04-21t01:51 (X15)mentioning

confidence: 99%

The Relationship Between Solar Radio and Hard X-ray Emission

White¹,

Benz²,

Christe³

et al. 2011

High-Energy Aspects of Solar Flares

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This review discusses the complementary relationship between radio and hard X-ray observations of the Sun using primarily results from the era of the Reuven Ramaty High Energy Solar Spectroscopic Imager satellite. A primary focus of joint radio and hard X-ray studies of solar flares uses observations of nonthermal gyrosynchrotron emission at radio wavelengths and bremsstrahlung hard X-rays to study the properties of electrons accelerated in the main flare site, since it is well established that these two emissions show very similar temporal behavior. A quantitative prescription is given for comparing the electron energy distributions derived separately from the two wavelength ranges: this is an important application with the potential for measuring the magnetic field strength in the flaring region, and reveals significant differences between the electrons in different energy ranges. Examples of the use of simultaneous data from the two wavelength ranges to derive physical conditions are then discussed, including the case of microflares, and the comparison of images at radio and hard X-ray wavelengths is presented. There have been puzzling results obtained from observations of solar flares at millimeter and submillimeter wavelengths, and the comparison of these results with corresponding hard X-ray data is presented. Finally, the review discusses the association of hard X-ray releases with radio emission at decimeter and meter wavelengths, which is dominated by plasma emission (at lower frequencies) and electron cyclotron maser emission (at higher frequencies), both coherent emission mechanisms that require small numbers of energetic electrons. These comparisons show broad general associations but detailed correspondence remains more elusive.

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“…Indeed, one notices that a pre-increase appeared in the ERNE time profile in the high-energy channels. According to Trottet et al (2008), the acceleration of particles during this solar eruption displays a complex temporal structure, suggesting that several episodes of acceleration occur. Thereby, the pre-increase can result from a different acceleration episode than the one accelerating the particles of the main particle flux.…”

Section: Resultsmentioning

confidence: 99%

The interplanetary magnetic structure that guides solar relativistic particles

Masson

Démoulin

Dasso

et al. 2012

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Context. Relating in-situ measurements of relativistic solar particles to their parent activity in the corona requires understanding the magnetic structures that guide them from their acceleration site to the Earth. Relativistic particle events are observed at times of high solar activity, when transient magnetic structures such as interplanetary coronal mass ejections (ICMEs) often shape the interplanetary magnetic field (IMF). They may introduce interplanetary paths that are longer than nominal, and magnetic connections rooted far from the nominal Parker spiral. Aims. We present a detailed study of the IMF configurations during ten relativistic solar particle events of the 23rd activity cycle to elucidate the actual IMF configuration that guides the particles to the Earth, where they are measured by neutron monitors. Methods. We used magnetic field (MAG) and plasma parameter measurements (SWEPAM) from the ACE spacecraft and determined the interplanetary path lengths of energetic particles through a modified version of the velocity dispersion analysis based on energetic particle measurements with SoHO/ERNE. Results. We find that the majority (7/10) of the events is detected in the vicinity of an ICME. Their interplanetary path lengths are found to be longer (1.5-2.6 AU) than those of the two events propagating in the slow solar wind (1.3 AU). The longest apparent path length is found in an event within the fast solar wind, probably caused by enhanced pitch angle scattering. The derived path lengths imply that the first energetic and relativistic protons are released at the Sun at the same time as electron beam emitting type III radio bursts. Conclusions. The timing of the first high-energy particle arrival on Earth is mainly determined by the type of IMF in which the particles propagate. Initial arrival times are as expected from Parker's model in the slow solar wind, and significantly longer in or near transient structures such as ICMEs.

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Radio Submillimeter and γ‐Ray Observations of the 2003 October 28 Solar Flare

Cited by 45 publications

References 29 publications

Origin of the 30 THz Emission Detected During the Solar Flare on 2012 March 13 at 17:20 UT

Origin of the 30 THz Emission Detected During the Solar Flare on 2012 March 13 at 17:20 UT

The Relationship Between Solar Radio and Hard X-ray Emission

The interplanetary magnetic structure that guides solar relativistic particles

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