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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Submillimeter Radiation as the Thermal Component of the Neupert Effect

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Valle Silva, Jorge F. [1] ; Guillermo Gimenez de Castro, C. [1, 2] ; Simoes, Paulo J. A. [3, 1] ; Raulin, Jean-Pierre [1]
Total Authors: 4
[1] Univ Presbiteriana Mackenzie, Escola Engn, Ctr Radio Astron & Astrofis Mackenzie, Rua Consolacao 896, BR-01302907 Sao Paulo, SP - Brazil
[2] UBA, CONICET, Inst & Astron & Fis Espacio, CC 67 Suc 28, RA-1428 Buenos Aires, DF - Argentina
[3] Univ Glasgow, SUPA Sch Phys & Astron, Glasgow G12 8QQ, Lanark - Scotland
Total Affiliations: 3
Document type: Journal article
Source: SOLAR PHYSICS; v. 294, n. 11 NOV 2019.
Web of Science Citations: 0

The Neupert effect is the empirical observation that the temporal evolution of non-thermal emission (e.g. hard X-rays) is frequently proportional to the temporal derivative of the thermal emission flux (soft X-rays), or vice versa, that time-integrated non-thermal flux is proportional to thermal flux. We analyzed the GOES M2.2 event SOL2011-02-14T17:25, and we found that the 212 GHz emission plays quite well the role of the thermal component of the Neupert effect. We show that the maximum of the hard X-ray flux for energies above 50 keV is coincident in time with the temporal derivative of the 212 GHz flux, within the uncertainties. The microwave flux density at 15.4 GHz, produced by optically thin gyrosyn-chrotron mechanism, and hard-X rays above 25 keV mark the typical impulsive phase, and they have similar temporal evolution. On the other hand, the 212 GHz emission is delayed by about 25 seconds with respect to the microwave and hard X-ray peak. We argue that this delay cannot be explained by magnetic trapping of non-thermal electrons. With all of the observational evidence, we suggest that the 212 GHz emission is produced by thermal bremsstrahlung, initially in the chromosphere, and shifting to optically thin emission from the hot coronal loops at the end of the gradual phase. (AU)

FAPESP's process: 13/24155-3 - Solar flare diagnostic in an unprecedented frequency range from microwaves to THz frequencies: challenges for interpretation (flat)
Grantee:Carlos Guillermo Giménez de Castro
Support type: Research Projects - Thematic Grants