Radio polarization and magnetic field structure in M101
文献类型：期刊论文
| 作者 | Berkhuijsen, E. M.1; Urbanik, M.2; Beck, R.1; Han, J. L.3
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| 刊名 | ASTRONOMY & ASTROPHYSICS
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| 出版日期 | 2016-04-01 |
| 卷号 | 588 |
| 关键词 | galaxies: individual: M 101 galaxies: magnetic fields galaxies: star formation radio continuum: galaxies polarization radiation mechanisms: non-thermal |
| 英文摘要 | We observed total and polarized radio continuum emission from the spiral galaxy M101 at lambda lambda 6.2 cm and 11.1 cm with the Effelsberg telescope. The angular resolutions are 2'.5 (=5.4 kpc) and 4'.4 (=9.5 kpc), respectively. We use these data to study various emission components in M101 and properties of the magnetic field. Separation of thermal and non-thermal emission shows that the thermal emission is closely correlated with the spiral arms, while the non-thermal emission is more smoothly distributed indicating diffusion of cosmic ray electrons away from their places of origin. The radial distribution of both emissions has a break near R = 16 kpc (= 7'.4), where it steepens to an exponential scale length of L similar or equal to 5 kpc, which is about 2.5 times smaller than at R < 16 kpc. The distribution of the polarized emission has a broad maximum near R = 12 kpc and beyond R = 16 kpc also decreases with L similar or equal to 5 kpc. It seems that near R = 16 kpc a major change in the structure of M101 takes place, which also affects the distributions of the strength of the random and ordered magnetic field. Beyond R = 16 kpc the radial scale length of both fields is about 20 kpc, which implies that they decrease to about 0.3 mu G at R = 70 kpc, which is the largest optical extent. The equipartition strength of the total field ranges from nearly 10 mu G at R < 2 kpc to 4 mu G at R = 22-24 kpc. As the random field dominates in M101 (B-ran/B-ord similar or equal to 2.4), wavelength-independent polarization is the main polarization mechanism. We show that energetic events causing Hi shells of mean diameter < 625 pc could partly be responsible for this. At radii < 24 kpc, the random magnetic field depends on the star formation rate/area, Sigma(SFR), with a power-law exponent of b = 0.28 +/- 0.02. The ordered magnetic field is generally aligned with the spiral arms with pitch angles that are about 8 degrees larger than those of Hi filaments. |
| 收录类别 | SCI |
| 语种 | 英语 |
| WOS记录号 | WOS:000373207800126 |
| 源URL | [http://ir.bao.ac.cn/handle/114a11/5364]  |
| 专题 | 国家天文台_射电天文研究部 |
| 作者单位 | 1.Max Planck Inst Radioastron, Hugel 69, D-53121 Bonn, Germany 2.Jagiellonian Univ, Astron Observ, Ul Orla 171, PL-30244 Krakow, Poland 3.Chinese Acad Sci, Natl Astron Observ, A20 Datun Rd, Beijing 100012, Peoples R China |
| 推荐引用方式 GB/T 7714 | Berkhuijsen, E. M.,Urbanik, M.,Beck, R.,et al. Radio polarization and magnetic field structure in M101[J]. ASTRONOMY & ASTROPHYSICS,2016,588. |
| APA | Berkhuijsen, E. M.,Urbanik, M.,Beck, R.,&Han, J. L..(2016).Radio polarization and magnetic field structure in M101.ASTRONOMY & ASTROPHYSICS,588. |
| MLA | Berkhuijsen, E. M.,et al."Radio polarization and magnetic field structure in M101".ASTRONOMY & ASTROPHYSICS 588(2016). |
入库方式： OAI收割
来源：国家天文台
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