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题名: 21 cm signals from early ionizing sources
作者: Liu, Jiren; Qiu, Jing-Mei; Feng LongLong(冯珑珑); Shu, Chi-Wang; Fang, Li-Zhi
刊名: ASTROPHYSICAL JOURNAL
出版日期: 2007-07-01
卷号: 663, 期号:1, 页码:1-9
关键词: cosmology : theory ; intergalactic medium ; methods : numerical ; radiative transfer
文章类型: Article
英文摘要: We investigate the 21 cm signals from the UV ionizing sources in the reionization epoch. The formation and evolution of 21 cm signals depend essentially on the kinetics of photons in the physical and frequency spaces, and we use the weighted essentially nonoscillatory algorithm to solve the radiative transfer equation. We show that a spherical shell of 21 cm signal will develop around a point source once the speed of the ionization front (I-front) is significantly lower than the speed of light. The 21 cm shell extends from the I-front to the front of light; its inner part is the emission region, and its outer part is the absorption region. The 21 cm emission region depends strongly on the intensity, frequency spectrum, and lifetime of the ionizing source. At redshift 1 + z = 20, for an ionizing source with intensity. E similar or equal to 10(45) ergs s(-1) and a power-law spectrum nu(-alpha) with alpha = 2, the emission region has a comoving size of 1-3 Mpc at time similar or equal to 2 Myr. Nevertheless, the emission region is very small if the intensity is less than. E similar or equal to 10(43) ergs s(-1), the spectrum is thermal at temperature T similar or equal to 10(5) K, or the spectral index alpha >= 3, while the 21 cm absorption region is prominent in all these cases. For a source of short lifetime, no 21 cm emission region can develop if the source dies out before the I-front speed is significantly lower than the speed of light. Yet, a 21 cm absorption region can form even after the emission of the source ceases.
WOS标题词: Science & Technology ; Physical Sciences
类目[WOS]: Astronomy & Astrophysics
研究领域[WOS]: Astronomy & Astrophysics
关键词[WOS]: LY-ALPHA FOREST ; INTERGALACTIC MEDIUM ; HIGH-REDSHIFT ; RADIATIVE-TRANSFER ; IONIZATION FRONTS ; WENO ALGORITHM ; 21-CM EMISSION ; 1ST GALAXIES ; POINT-SOURCE ; DARK-AGES
收录类别: SCI
语种: 英语
WOS记录号: WOS:000247542700001
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内容类型: 期刊论文
URI标识: http://libir.pmo.ac.cn/handle/332002/15859
Appears in Collections:南极天文中心_期刊论文

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作者单位: 1.Univ Arizona, Dept Phys, Tucson, AZ 85721 USA
2.Brown Univ, Div Appl Math, Providence, RI 02912 USA
3.Acad Sinica, Purple Mt Observ, Nanjing 210008, Peoples R China
4.Chinese Acad Sci, Natl Astron Observ, Beijing 100012, Peoples R China
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