On the origin of 140 GHz emission from the 4 July 2012 solar flare

Tsap, Yu. T.; Smirnova, V. V.; Morgachev, A. S.; Motorina, G. G.; Kontar, Eduard P.; Nagnibeda, V. G.; Strekalova, P. V.

doi:10.1016/j.asr.2015.12.037

Cited by 16 publications

(4 citation statements)

References 31 publications

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“…We note, however, that at mm-waves, the contribution from synchrotron emission from non-thermal electrons may become important or even dominant (e.g. Trottet et al 2002Trottet et al , 2011Lüthi et al 2004b,a;Giménez de Castro et al 2013;Tsap et al 2016;Fernandes et al 2017).…”

Section: Discussionmentioning

confidence: 99%

Formation of the thermal infrared continuum in solar flares

Simões

Kerr

Fletcher

et al. 2017

A&A

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Aims. Observations of the Sun with the Atacama Large Millimeter Array have now started, and the thermal infrared will regularly be accessible from the NSF's Daniel K. Inouye Solar Telescope. Motivated by the prospect of these new data, and by recent flare observations in the mid infrared, we set out here to model and understand the source of the infrared continuum in flares, and to explore its diagnostic capability for the physical conditions in the flare atmosphere. Methods. We use the one-dimensional (1D) radiation hydrodynamics code RADYN to calculate mid-infrared continuum emission from model atmospheres undergoing sudden deposition of energy by non-thermal electrons. Results. We identify and characterise the main continuum thermal emission processes relevant to flare intensity enhancement in the mid-to far-infrared (2-200 µm) spectral range as free-free emission on neutrals and ions. We find that the infrared intensity evolution tracks the energy input to within a second, albeit with a lingering intensity enhancement, and provides a very direct indication of the evolution of the atmospheric ionisation. The prediction of highly impulsive emission means that, on these timescales, the atmospheric hydrodynamics need not be considered in analysing the mid-IR signatures.

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Section: Discussionmentioning

confidence: 99%

Formation of the thermal infrared continuum in solar flares

Simões

Kerr

Fletcher

et al. 2017

A&A

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“…The pink solid line in this panel shows the optically thin 17 GHz free-free emission produced by the hot plasma inferred from GOES observations (Tsap et al 2016). It shows gradual evolution and is about a factor of 3 lower than the radio flux density observed with the NoRH.…”

Section: Light Curvesmentioning

confidence: 97%

“…The RHESSI spectral analysis has already revealed multiple thermal components. More detailed analyses of SDO/AIA observations can give a quantitative measurement of the differential emission measure, which can be used to derive contributions to the gradual radio emission from different thermal components (Tsap et al 2016). The flare in general has a complex magnetic field structure.…”

Section: Euv and X-ray Images And Magnetic Field Extrapolationmentioning

confidence: 99%

Impulsive radio and hard X-ray emission from an M-class flare

Zhang

Guo

Wang

et al. 2018

A&A

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Context. Impulsive radio and hard X-ray emission from large solar flares are usually attributed to a hard distribution of high-energy electrons accelerated in the energy dissipation process of magnetic reconnection. Aims. We report the detection of impulsive radio and hard X-ray emissions produced by a population of energetic electrons with a very soft distribution in an M-class flare: SOL2015-08-27T05:45 . Methods. The absence of impulsive emission at 34 GHz and hard X-ray emission above 50 keV and the presence of distinct impulsive emission at 17 GHz and lower frequencies and in the 25-50 keV X-ray band imply a very soft distribution of energetic electrons producing the impulsive radio emission via the gyro-synchrotron process, and impulsive X-rays via bremsstrahlung. Results. The spectrum of the impulsive hard X-ray emission can be fitted equally well with a power-law model with an index of ∼6.5 or a super-hot thermal model with a temperature as high as 100 MK. Imaging observations in the extreme-UV and X-ray bands and extrapolation of the magnetic field structure using a nonlinear force-free model show that energetic electrons trapped in coronal loops are responsible for these impulsive emissions. Conclusions. Since the index of the power-law model is nearly constant during the impulsive phase, the power-law distribution or the super-hot component should be produced by a bulk energization process such as the Fermi and betatron acceleration of collapsing magnetic loops.

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“…Н.Э. Баумана[2], которые представлены на рис.2. Видно, что максимум суб-ТГц излучения не совпадает с импульсной фазой вспышки.…”

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