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翻訳と辞書　辞書検索 [ 開発暫定版 ] スポンサード リンク Wouthuysen–Field coupling ： ウィキペディア英語版 Wouthuysen–Field coupling Wouthuysen–Field coupling, or the Wouthuysen–Field effect, is a mechanism that couples the excitation temperature, also called the spin temperature, of neutral hydrogen to Lyman-alpha radiation. This coupling plays a role in producing a difference in the temperature of neutral hydrogen and the cosmic microwave background at the end of the Dark Ages and the beginning of the epoch of reionization. It is named for Siegfried Adolf Wouthuysen and George B. Field. ==Background== The period after recombination occurred and before stars and galaxies formed is known as the "dark ages". During this time, the majority of matter in the universe is neutral hydrogen. This hydrogen has yet to be observed, but there are experiments underway to detect the hydrogen line produced during this era. The hydrogen line is produced when an electron in a neutral hydrogen atom is excited to a state where the electron and proton have aligned spins, or de-excited as the electron and proton spins go from being aligned to anti-aligned. The energy difference between these two hyperfine states is $5.9\; \backslash times\; 10^$ electron volts, with a wavelength of 21 centimeters. At times when neutral hydrogen is in thermodynamic equilibrium with the photons in the cosmic microwave background (CMB), the neutral hydrogen and CMB are said to be "coupled", and the hydrogen line is not observable. It is only when the two temperatures differ, or decoupled, that the hydrogen line can be observed.〔Stiavelli (2009), p. 121.〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Wouthuysen–Field coupling」の詳細全文を読む スポンサード リンク 翻訳と辞書 : 翻訳のためのインターネットリソース Copyright(C) kotoba.ne.jp 1997-2016. All Rights Reserved.