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TRANSCRIPT
Alan Guth, Cosmology, 8.962 Lecture 26, May 16, 2018, p. 1.
8.962 Lecture 26
May 16, 2018
COSMOLOGY
Ripples in the Cosmic Microwave Background
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Spectrum of CMB Ripples
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Planck 2015 TE Power Spectrum
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Alan Guth, Cosmology, 8.962 Lecture 26, May 16, 2018, p. 2.
Planck 2015 EE Power Spectrum
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Gaussianity of the CMB
Nongaussianites are measured by fNL, where Planck 2015 set thebounds
f localNL = 0.8± 5.0 ,
f equilNL = −4± 43 ,
forthoNL = −26± 21 (68% CL statistical).
Local, equil, and ortho refer to three different “shapes” for the3-point function (bispectrum). fNL is defined by
Φ = Φg + fNLΦ2g ,
where Φ is the Bardeen potential. Note that the nongaussian termwill be comparable to the gaussian term when fNL ∼ 105, so thelimits imply that the CMB is VERY gaussian.
Alan Guth
Massachusetts Institute of Technology
8.962 Lecture 26, May 16, 2018 –5–