查看“︁B模”︁的源代码

{{NoteTA
|1=zh-hans:引力波; zh-hant:重力波;
}}
[[Image:Gravitational lens-full.jpg|thumb|right|藝術繪圖顯示出，早期宇宙時期的光束，在傳播通過宇宙空間之時，怎樣被大質量宇宙構造所產生的引力透鏡效應所偏轉，形成B模。（Credit: ESA）]]

'''B模偏振'''（B-mode polarization）是[[宇宙微波背景輻射]]的一種[[偏振]]信號。 宇宙微波背景輻射的偏振圖樣可以分為兩個部分。一個是[[旋度]]為零的部分（類[[電場]]部分），稱為「E模偏振」，簡稱為「E模」，不具[[手徵性]]。2002年，[[度角尺度干涉儀]]（DASI）最先發現這種偏振。另一個是[[散度]]為零、旋度不為零的部分（類[[磁場]]部分），稱為「B模偏振」，簡稱為「B模」，具有手徵性。<ref>[http://cosmology.berkeley.edu/~yuki/CMBpol/CMBpol.htm Cosmic Microwave Background Polarization: The Next Key Toward the Origin of the Universe] {{Wayback|url=http://cosmology.berkeley.edu/~yuki/CMBpol/CMBpol.htm |date=20140215090233 }}, 2003, Yuki D. Takahashi</ref>

[[宇宙學家]]預測存在兩種B模。第一種是在[[大爆炸]]短暫片刻後的[[宇宙暴脹]]過程中生成<ref>{{cite journal
|first=U.|last=Seljak
|title=Measuring Polarization in the Cosmic Microwave Background
|journal=Astrophysical Journal|date=June 1997|volume=482|page=6
|doi=10.1086/304123
}}</ref><ref>{{cite journal
|first=U.|last=Seljak|coauthors=Zaldarriaga M.
|title=Signature of Gravity Waves in the Polarization of the Microwave Background
|journal=Phys. Rev.Lett.|date=March 17, 1997|volume=78|issue=11
|doi=10.1103/PhysRevLett.78.2054
}}</ref><ref>{{cite journal
|first=M.|last=Kamionkowski|coauthors= Kosowsky A. & Stebbins A.
|title=A Probe of Primordial Gravity Waves and Vorticity
|journal=Phys. Rev.Lett.|date=March 17, 1997|volume=78|issue=11
|doi=10.1103/PhysRevLett.78.2058
}}</ref>；第二種在後來由[[引力透鏡]]生成<ref>{{cite journal
|first=M.|last=Zaldarriaga|coauthors=Seljak U.
|title=Gravitational lensing effect on cosmic microwave background polarization
|journal=Physical Review D|date=July 15, 1998|volume=58|series=2
|doi=10.1103/PhysRevD.58.023003
}}</ref>。

==研究成果==
2014年3月，[[BICEP2]]科學家團隊宣佈探測到第一種B模，符合早期宇宙暴脹期間所產生的[[引力波]]，純量-張量比為 <math>r=0.2^{+0.07}_{-0.05}</math> <ref name="bmodes">{{cite news | url=http://www.theguardian.com/science/2014/mar/14/gravitational-waves-big-bang-universe-bicep | title=Gravitational waves: have US scientists heard echoes of the big bang? | 3= | publisher=[[The Guardian]] | date=2014-03-14 | accessdate=2014-03-14 | archive-date=2018-01-18 | archive-url=https://web.archive.org/web/20180118154832/https://www.theguardian.com/science/2014/mar/14/gravitational-waves-big-bang-universe-bicep | dead-url=no }}</ref><ref>{{Cite web |url=http://www.nytimes.com/2014/03/18/science/space/detection-of-waves-in-space-buttresses-landmark-theory-of-big-bang.html |title=存档副本 |accessdate=2014-03-19 |archive-date=2018-02-19 |archive-url=https://web.archive.org/web/20180219222002/https://www.nytimes.com/2014/03/18/science/space/detection-of-waves-in-space-buttresses-landmark-theory-of-big-bang.html?_r=0 |dead-url=no }}</ref>。2015年1月30日，研究團隊承認對於資料的判讀錯誤，觀測到的信號無法排除掉銀河系輻射塵埃的影響，不足以證實這項結果就是早期宇宙的引力波所形成的B模偏振<ref>{{cite web
| last =Cho
| first =Adrian
| title =Curtain falls on controversial big bang result
| work =Science
| date =2015-01-30
| url =http://news.sciencemag.org/physics/2015/01/curtain-falls-controversial-big-bang-result
| accessdate =2015-03-05
| archive-date =2015-03-12
| archive-url =https://web.archive.org/web/20150312220353/http://news.sciencemag.org/physics/2015/01/curtain-falls-controversial-big-bang-result
| dead-url =no
}}</ref>。

此前，[[南極望遠鏡]]已發現了第二種B模。這發現可能有助於檢驗有關宇宙起源的理論。科學家現在正在使用[[普朗克衛星]]所測得的數據做分析，希望能夠更進一步了解這些引力波。<ref>{{cite web
|last=ESA Planck
|title=Planck Space Mission
|url=http://www.esa.int/Our_Activities/Space_Science/Planck
|date=Oct 22, 2013
|accessdate=Oct 23, 2013
|archive-date=2017-12-08
|archive-url=https://web.archive.org/web/20171208015949/http://www.esa.int/Our_Activities/Space_Science/Planck
|dead-url=no
}}</ref><ref>{{cite web
|last=NASA/Jet Propulsion Laboratory
|title=Long-sought pattern of ancient light detected
|journal=ScienceDaily
|date=2013-10-22|accessdate=October 23, 2013
|url=http://www.sciencedaily.com/releases/2013/10/131022101009.htm
|archive-date=2014-04-07
|archive-url=https://web.archive.org/web/20140407092754/http://www.sciencedaily.com/releases/2013/10/131022101009.htm
|dead-url=no
}}</ref><ref>{{cite journal
|first=D.|last=Hanson|coauthors=et al
|title=Detection of B-Mode Polarization in the Cosmic Microwave Background with Data from the South Pole Telescope
|journal=Physical Review Letters|date=Sep 30, 2013|volume=111|series=14
|doi=10.1103/PhysRevLett.111.141301
}}</ref>

== 參考文獻 ==
{{reflist}}

{{Relativity}}
{{DEFAULTSORT:B}}
[[Category:天體物理學]]
[[Category:重力透鏡]]