Millimeter and X-Ray Emission from the 5 July 2012 Solar Flare

Tsap, Yu. T.; Smirnova, V. V.; Motorina, G. G.; Morgachev, A. S.; Кузнецов, С. А.; Nagnibeda, V. G.; Ryzhov, V.S.

doi:10.1007/s11207-018-1269-6

Cited by 17 publications

(7 citation statements)

References 48 publications

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“…In the last panel of figure 1, we showed the centimeter microwave measurements from RSTN (Radio Solar Telescope Network,San vito) at 1.4,2.7,4.9,8.8 and 15.4 GHz (Guidice et al 1981;Tsap et al 2018). The radio emission at 1.4GHz has a rather lower flux density than those at higher frequencies during the X9.3 flare, the pattern of 2.7 GHz flux showed several impulsive peaks during the impulsive phase.…”

Section: Observationsmentioning

confidence: 99%

Non-thermal electron energization during the impulsive phase of an X9.3 flare revealed by Insight-HXMT

Zhang,

Wang,

et al. 2021

Preprint

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The X9.3 flare SOL20170906T11:55 was observed by the CsI detector aboard the first Chinese Xray observatory Hard X-ray Modulation telescope (Insight-HXMT). By using wavelets method, we report about 22s quasiperiodic pulsations(QPPs) during the impulsive phase. And the spectra from 100 keV to 800 keV showed the evolution with the gamma-ray flux, of a power-law photon index from ∼ 1.8 before the peak, ∼ 2.0 around the flare peak, to ∼ 1.8 again. The gyrosynchrotron microwave spectral analysis reveals a 36.6 ± 0.6 radius gyrosynchrotron source with mean transverse magnetic field around 608.2 Gauss, and the penetrated ≥ 10 keV non-thermal electron density is about 10 6.7 cm −3 at peak time. The magnetic field strength followed the evolution of high-frequency radio flux. Further gyrosynchrotron source modeling analysis implies that there exists a quite steady gyrosynchrotron source, the non-thermal electron density and transverse magnetic field evolution are similar to higherfrequency light curves. The temporally spectral analysis reveals that those non-thermal electrons are accelerated by repeated magnetic reconnection, likely from a lower corona source.

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Section: Observationsmentioning

confidence: 99%

Non-thermal electron energization during the impulsive phase of an X9.3 flare revealed by Insight-HXMT

Zhang,

Wang,

et al. 2021

Preprint

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“…The literature is vast and selected references will be provided in sections 6.2-6.4, primarily for publications that link modeling of gyrosynchrotron emission with observations. Gyrosynchrotron radiation can also be detected at millimeter wavelengths and is produced by electrons with energies of more than 1 MeV (e.g., White and Kundu, 1992;Kundu et al, 1994;Silva et al, 1996;Raulin et al, 1999;Silva and Valio, 2016;Tsap et al, 2018). (2) Weak transient brightenings, when observed at microwaves, may sometimes show emission consistent with the properties of gyrosynchrotron radiation (e.g., Gary et al, 1997;Krucker et al, 1997;Nindos et al, 1999;Kundu et al, 2006).…”

Section: General Remarksmentioning

confidence: 99%

Incoherent Solar Radio Emission

Nindos

2020

Front. Astron. Space Sci.

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Incoherent solar radio radiation comes from the free-free, gyroresonance, and gyrosynchrotron emission mechanisms. Free-free is primarily produced from Coulomb collisions between thermal electrons and ions. Gyroresonance and gyrosynchrotron result from the acceleration of low-energy electrons and mildly relativistic electrons, respectively, in the presence of a magnetic field. In the non-flaring Sun, free-free is the dominant emission mechanism with the exception of regions of strong magnetic fields which emit gyroresonance at microwaves. Due to its ubiquitous presence, free-free emission can be used to probe the non-flaring solar atmosphere above temperature minimum. Gyroresonance opacity depends strongly on the magnetic field strength and orientation; hence it provides a unique tool for the estimation of coronal magnetic fields. Gyrosynchrotron is the primary emission mechanism in flares at frequencies higher than 1-2 GHz and depends on the properties of both the magnetic field and the accelerated electrons, as well as the properties of the ambient plasma. In this paper we discuss in detail the above mechanisms and their diagnostic potential.

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“…They also observed that 345 GHz is optically thick and should come from a lower height. In our case, if the emission were optically thick gyrosynchrotron, the spectral index between 212 and 405 GHz, α ≃ 0.8, would indicate an inhomogeneous source (Klein & Trottet, ; Simões & Costa, ), while Tsap et al () propose a mixture of gyrosynchrotron and thermal bremsstrahlung absorption to explain the spectral increase between 93 and 140 GHz during SOL2012‐07‐05T11:44. The mid‐IR flux can be explained, as in Trottet et al (), as optically thin thermal bremsstrahlung emission of a heated chromospheric plasma, since fluxes of the two events are similar.…”

Section: Discussionmentioning

confidence: 58%

The 6 September 2017 X9 Super Flare Observed From Submillimeter to Mid‐IR

et al. 2018

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Active Region 12673 is the most productive active region of solar cycle 24: in a few days of early September 2017, four X‐class and 27 M‐class flares occurred. SOL2017‐09‐06T12:00, an X9.3 flare also produced a two‐ribbon white light emission across the sunspot detected by Solar Dynamics Orbiter/Helioseismic and Magnetic Imager. The flare was observed at 212 and 405 GHz with the arcminute‐sized beams of the Solar Submillimeter Telescope focal array while making a solar map and at 10 μm, with a 17 arcsec diffraction‐limited infrared camera. Images at 10 μm revealed that the sunspot gradually increased in brightness while the event proceeded, reaching a temperature similar to quiet Sun values. From the images we derive a lower bound limit of 180‐K flare peak excess brightness temperature or 7,000 sfu if we consider a similar size as the white light source. The rising phase of mid‐IR and white light is similar, although the latter decays faster, and the maximum of the mid‐IR and white light emission is ∼200 s delayed from the 15.4‐GHz peak occurrence. The submillimeter spectrum has a different origin than that of microwaves from 1 to 15 GHz, although it is not possible to draw a definitive conclusion about its emitting mechanism.

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Millimeter and X-Ray Emission from the 5 July 2012 Solar Flare

Cited by 17 publications

References 48 publications

Non-thermal electron energization during the impulsive phase of an X9.3 flare revealed by Insight-HXMT

Non-thermal electron energization during the impulsive phase of an X9.3 flare revealed by Insight-HXMT

Incoherent Solar Radio Emission

The 6 September 2017 X9 Super Flare Observed From Submillimeter to Mid‐IR

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