Turnover Frequency in Solar Microwave Bursts with an Extremely Flat Optically Thin Spectrum
文献类型：期刊论文
| 作者 | 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
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| 刊名 | SOLAR PHYSICS
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| 出版日期 | 2016-12-01 |
| 卷号 | 291期号:12页码:3619-3635 |
| ISSN号 | 0038-0938 |
| 关键词 | Energetic particles Sun corona Sun flares Sun magnetic fields |
| DOI | 10.1007/s11207-016-1004-0 |
| 通讯作者 | Huang, G. L.(glhuang@pmo.ac.cn) |
| 英文摘要 | Four 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. |
| WOS关键词 | CORONAL MAGNETIC-FIELD ; LOW-CUTOFF ENERGY ; X-RAY-BURSTS ; GYROSYNCHROTRON RADIATION ; NONTHERMAL ELECTRONS ; RADIO-EMISSION ; GAMMA-RAY ; FLARES ; SUBMILLIMETER ; NOBEYAMA |
| WOS研究方向 | Astronomy & Astrophysics |
| 语种 | 英语 |
| 出版者 | SPRINGER |
| WOS记录号 | WOS:000389417400011 |
| 源URL | [http://libir.pmo.ac.cn/handle/332002/23411]  |
| 专题 | 中国科学院紫金山天文台 |
| 通讯作者 | Huang, G. L. |
| 作者单位 | 1.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 |
| 推荐引用方式 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. |
入库方式： OAI收割
来源：紫金山天文台
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