mca 發表於 2016-6-18 12:30:30

LIGO 再次發現引力波

本文章最後由 mca 於 2016-6-18 13:22 編輯

上次是 GW150914(2015 年 9 月 14 日發現)
今次是 GW151226(2015 年 12 月 26 日發現)

GW151226 簡略
在 LIGO 出現的引力波持續時間   約 1 秒
在 LIGO 出現的引力波頻率變化   55 cycles from 35 to 450 Hz
引力波使 LIGO 臂長變化 (Strain)   3.4 x 10^-22
匹配模型: 引力波由星黑洞併合產生
               合併前星黑洞質量   14.2 M⊙ + 7.5 M⊙
               合併後單黑洞質量   20.8 M⊙
               黑洞光度距離   440 Mpc / 14 億光年(紅移 = 0.09)
http://www.ligo.org/science/Publication-GW151226/images/Fig5_v6.png

資料來源
LIGO 網頁   http://www.ligo.org/science/Publication-GW151226/index.php

APOD 網頁http://apod.nasa.gov/apod/ap160615.html
引力波頻率變化 的 音頻模擬動畫

APS 網頁   http://journals.aps.org/prl/abst ... sRevLett.116.241103
We report the observation of a gravitational-wave signal produced by the coalescence of two stellar-mass black holes. The signal, GW151226, was observed by the twin detectors of the Laser Interferometer Gravitational-Wave Observatory (LIGO) on December 26, 2015 at 03:38:53 UTC. The signal was initially identified within 70 s by an online matched-filter search targeting binary coalescences. Subsequent off-line analyses recovered GW151226 with a network signal-to-noise ratio of 13 and a significance greater than 5σ. The signal persisted in the LIGO frequency band for approximately 1 s, increasing in frequency and amplitude over about 55 cycles from 35 to 450 Hz, and reached a peak gravitational strain of 3.4 −0.9+0.7×10^−22. The inferred source-frame initial black hole masses are 14.2 −3.7+8.3M⊙ and 7.5−2.3+2.3M⊙, and the final black hole mass is 20.8 −1.7+6.1M⊙. We find that at least one of the component black holes has spin greater than 0.2. This source is located at a luminosity distance of 440 −190+180 Mpc corresponding to a redshift of 0.09 −0.04+0.03. All uncertainties define a 90% credible interval. This second gravitational-wave observation provides improved constraints on stellar populations and on deviations from general relativity.






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