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Turnover Frequency in Solar Microwave Bursts with an Extremely Flat Optically Thin Spectrum
Song, Q. W.1,2; Nakajima, H.3; Huang, G. L.1,2; Tan, B. L.4,5; Huang, Y.1,2; Wu, Z.6,7
2016-12-01
Source PublicationSOLAR PHYSICS
ISSN0038-0938
Volume291Issue:12Pages:3619-3635
Corresponding AuthorHuang, G. L.(glhuang@pmo.ac.cn)
AbstractFour microwave bursts have been selected from the Nobeyama Radio Polarimeter (NoRP) observations with an extremely flat spectrum in the optically thin part and a very hard spectral index between 0 and -1 in the maximum phase of all bursts. It is found that the time evolution of the turnover frequency is inversely proportional to the time profiles of the radio flux in all bursts. Based on the nonthermal gyrosynchrotron theory of Ramaty (Astrophys. J. 158, 753, 1969), the local magnetic field strength and the electron spectral index are calculated uniquely from the observed radio spectral index and the turnover frequency. We found that the electron energy spectrum is very hard (spectral index 1 - 2), and the time variation of the magnetic field strength is also inversely proportional to the radio flux as a function of time in all bursts. Hence, the time evolution of the turnover frequency can be explained directly by its dependence on the local magnetic field strength. The high turnover frequency (several tens of GHz) is mainly caused by a strong magnetic field of up to several hundred gauss, and probably by the Razin effect under a high plasma density over 10(10) cm (3) in the maximum phase of these bursts. Therefore, the extremely flat microwave spectrum can be well understood by the observed high turnover frequency and the calculated hard electron spectral index.
KeywordEnergetic particles Sun corona Sun flares Sun magnetic fields
DOI10.1007/s11207-016-1004-0
WOS KeywordCORONAL MAGNETIC-FIELD ; LOW-CUTOFF ENERGY ; X-RAY-BURSTS ; GYROSYNCHROTRON RADIATION ; NONTHERMAL ELECTRONS ; RADIO-EMISSION ; GAMMA-RAY ; FLARES ; SUBMILLIMETER ; NOBEYAMA
Indexed BySCI
Language英语
WOS Research AreaAstronomy & Astrophysics
WOS SubjectAstronomy & Astrophysics
WOS IDWOS:000389417400011
PublisherSPRINGER
Citation statistics
Cited Times:3[WOS]   [WOS Record]     [Related Records in WOS]
Document Type期刊论文
Identifierhttp://libir.pmo.ac.cn/handle/332002/23412
Collection中国科学院紫金山天文台
Corresponding AuthorHuang, G. L.
Affiliation1.Chinese Acad Sci, Purple Mt Observ, Nanjing 210008, Jiangsu, Peoples R China
2.Chinese Acad Sci, Key Lab Space Astron & Dark Matter, Nanjing 210008, Jiangsu, Peoples R China
3.NAOJ, Nobeyama Radio Observ, Minamisa Ku, Minamimaki, Nagano 3841305, Japan
4.Chinese Acad Sci, Natl Astron Observ, Beijing 100012, Peoples R China
5.Chinese Acad Sci, Key Lab Solar Act, Beijing, Peoples R China
6.Shandong Univ, Inst Space Sci, Weihai 264209, Peoples R China
7.Shandong Univ, Sch Space Sci & Phys, Weihai 264209, Peoples R China
Recommended Citation
GB/T 7714
Song, Q. W.,Nakajima, H.,Huang, G. L.,et al. Turnover Frequency in Solar Microwave Bursts with an Extremely Flat Optically Thin Spectrum[J]. SOLAR PHYSICS,2016,291(12):3619-3635.
APA Song, Q. W.,Nakajima, H.,Huang, G. L.,Tan, B. L.,Huang, Y.,&Wu, Z..(2016).Turnover Frequency in Solar Microwave Bursts with an Extremely Flat Optically Thin Spectrum.SOLAR PHYSICS,291(12),3619-3635.
MLA Song, Q. W.,et al."Turnover Frequency in Solar Microwave Bursts with an Extremely Flat Optically Thin Spectrum".SOLAR PHYSICS 291.12(2016):3619-3635.
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