Influence of synchrotron self-absorption on 21-cm experiments
文献类型：期刊论文
| 作者 | Zheng, Qian1,2,3; Wu, Xiang-Ping1 ; Gu, Jun-Hua1; Wang, Jingying4; Xu, Haiguang4
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| 刊名 | MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
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| 出版日期 | 2012-08-01 |
| 卷号 | 424期号:4页码:2562-2573 |
| 关键词 | intergalactic medium cosmology: observations cosmology: theory dark ages reionization first stars diffuse radiation radio lines: galaxies |
| 英文摘要 | The presence of spectral curvature resulting from the synchrotron self-absorption of extragalactic radio sources could break down the spectral smoothness feature. This leads to the premise that the bright radio foreground can be successfully removed in 21-cm experiments that search for the epoch of reionization (EoR). We present a quantitative estimate of the effect of the spectral curvature resulting from the synchrotron self-absorption of extragalactic radio sources on the measurement of the angular power spectrum of the low-frequency sky. We incorporate a phenomenological model, which is characterized by the fraction (f) of radio sources with turnover frequencies in the range of 1001000?MHz and by a broken power law for the spectral transition around the turnover frequencies nu m, into simulated radio sources over a small sky area of 10 degrees x 10 degrees. We compare statistically the changes in their residual maps with and without the inclusion of the synchrotron self-absorption of extragalactic radio sources after the bright sources of S150 MHz >= 100mJy are excised. Furthermore, the best-fitting polynomials in the frequency domain on each pixel are subtracted. It has been shown that the effect of synchrotron self-absorption on the detection of the EoR depends sensitively on the spectral profiles of the radio sources around the turnover frequencies nu m. A hard transition model, described by the broken power law with the turnover of spectral index at nu m, would leave pronounced imprints on the residual background and would therefore cause serious confusion with the cosmic EoR signal. However, the spectral signatures on the angular power spectrum of the extragalactic foreground, generated by a soft transition model in which the rising and falling power laws of the spectral distribution around nu m are connected through a smooth transition spanning >= 200 MHz in a characteristic width, can be fitted and consequently subtracted by the use of polynomials to an acceptable degree (delta T < 1mK). As this latter scenario seems to be favoured in both theoretical expectations and radio spectral observations, we conclude that the contamination of extragalactic radio sources by synchrotron self-absorption in 21-cm experiments is probably very minor. |
| 收录类别 | SCI |
| 语种 | 英语 |
| WOS记录号 | WOS:000307385100012 |
| 源URL | [http://ir.bao.ac.cn/handle/114a11/6071]  |
| 专题 | 国家天文台_星系宇宙学研究部 |
| 作者单位 | 1.Chinese Acad Sci, Natl Astron Observ, Beijing 100012, Peoples R China 2.Observ Paris, LERMA, F-75014 Paris, France 3.Chinese Acad Sci, Grad Sch, Beijing 100049, Peoples R China 4.Shanghai Jiao Tong Univ, Dept Phys, Shanghai 200240, Peoples R China |
| 推荐引用方式 GB/T 7714 | Zheng, Qian,Wu, Xiang-Ping,Gu, Jun-Hua,et al. Influence of synchrotron self-absorption on 21-cm experiments[J]. MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY,2012,424(4):2562-2573. |
| APA | Zheng, Qian,Wu, Xiang-Ping,Gu, Jun-Hua,Wang, Jingying,&Xu, Haiguang.(2012).Influence of synchrotron self-absorption on 21-cm experiments.MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY,424(4),2562-2573. |
| MLA | Zheng, Qian,et al."Influence of synchrotron self-absorption on 21-cm experiments".MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY 424.4(2012):2562-2573. |
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