耿恩-彼得森槽


耿恩-彼得森槽（英语：Gunn-Peterson trough）是類星體的光譜在天體光譜中的一個特徵，它是由星系際物質 (IGM)的中性氫造成的。槽的特徵是受到來自類星體波長小於萊曼α的電磁發射在紅移壓抑的發射線。詹姆斯·冈恩和布魯斯·彼德森在1965年就預測了這種效應[1]。




目录





  • 1 第一次的發現


  • 2 再電離的證據


  • 3 相關條目


  • 4 參考資料




第一次的發現


在預測之後的30年，還沒有發現遠到足以展現耿恩-彼得森槽的天體。直到2001年，羅伯特·貝克爾使用史隆數位巡天的資料發現一個紅移值(z)=6.28displaystyle (z)=6.28displaystyle (z)=6.28I的類星體[2]，才終於發現耿恩-彼得森槽。這篇論文還包括紅移為z=5.82displaystyle z=5.82displaystyle z=5.82和z=5.99displaystyle z=5.99displaystyle z=5.99的類星體，和轉換到藍色一側的萊曼α線，以及許多通量中明顯的峰值。然而，紅移量為z=6.28displaystyle z=6.28displaystyle z=6.28的類星體，在超越萊曼α線限制的通量為0，也就是說中性氫在IGM的分數必須已經大於10−3。



再電離的證據


参见：再電離

在紅移z=6.28displaystyle z=6.28displaystyle z=6.28的類星體發現了槽，和在紅移低於z=6displaystyle z=6displaystyle z=6的類星體中檢測不到槽的存在，對宇宙中的氫曾經從中性氫轉換成電離氫提出了強且有力的證據。在復合後，宇宙成為中性的，直到在宇宙中的第一個天體發出光和能量，將周圍的IGM 再電離。然而，光子對中性氫的散射截面積在接近萊曼α限制的能量是很高的，甚至有一小部份的中性氫會因為IGM的光深度太高而造成發射線的觀測受到抑制。儘管中性氫和電離氫的比例並不是特別的高，通過觀測到低流量的萊曼α限制，顯示宇宙是在再電離的最後階段。


從WMAP太空船在2003年第一次釋放出來的資料，貝克測量再電離結束在zdisplaystyle zz ≈ 6displaystyle 66，似乎與WMAP測量到的電子密度估計值有所衝突[3]。然而，WMAP在2006年發布的第三批資料，與再電離的極限和耿恩-彼得森槽之間的關連似乎有了更好的協調[4]。



相關條目



  • 萊曼α森林


參考資料




  1. ^ Gunn, J.E.; Peterson, B.A. On the Density of Neutral Hydrogen in Intergalactic Space. Astrophysical Journal. 1965, 142: 1633–1641. Bibcode:1965ApJ...142.1633G. doi:10.1086/148444.  引文使用过时参数coauthors (帮助)


  2. ^ Becker, R. H.; et al.. Evidence For Reionization at z ~ 6: Detection of a Gunn-Peterson Trough In A z=6.28 Quasar. Astronomical Journal. 2001, 122 (6): 2850–2857. Bibcode:2001AJ....122.2850B. arXiv:astro-ph/0108097. doi:10.1086/324231.  引文使用过时参数coauthors (帮助)


  3. ^ Kogut, A.; et al.. First-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Temperature-Polarization Correlation. Astrophysical Journal Supplement Series. 2003, 148 (1): 161–173. Bibcode:2003ApJS..148..161K. arXiv:astro-ph/0302213. doi:10.1086/377219.  引文使用过时参数coauthors (帮助)


  4. ^ Page, L.; et al.. Three-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Polarization Analysis. Astrophysical Journal Supplement Series. 2007, 170 (2): 335–376. Bibcode:2007ApJS..170..335P. arXiv:astro-ph/0603450. doi:10.1086/513699.  引文使用过时参数coauthors (帮助)








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