V. The Thermal Beginning of the Universe

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1 V. The Thermal Beginning of the Universe I. Aretxaga Jan 2014

CMB discovery time-line -1947-1948 Gamow, Alpher and Hermans model of nucleosynthesis predicts relic millimeter radiation, but the models have difficulties to produce elements heavier than Li, leads

2 CMB discovery time-line Gamow, Alpher and Hermans model of nucleosynthesis predicts relic millimeter radiation, but the models have difficulties to produce elements heavier than Li, leads to its neglect Arno Penzias & Robert Wilson s serendipitous discovery of a constant excess isotropic noise with their antenna at Bell Labs (Nobel 1978). -late 60 s many groups made measurements of the intensity of the radiation and a temperature collectively showing the spectrum is that of a BB (to 10% accuracy) Tentative detection of a dipole anisotropy by Conklin, confirmed in by Henry, Wilkinson, and Smooth et al COBE (COsmic Background Explorer) launched, in 1990 first results confirming BB spectrum COBE s detection of non-dipole anisotropies (nobel prize 2006 for PI s Smoot & Mather WMAP results on precission cosmology through CMB anisotropies Planck s results (Following E. Wright s CMB review paper)

3 Dominant background radiation GTM The photons of the CMB are still the largest contributors to the radiation energy in the Universe.

4 CMB spectrum An almost perfect BB was measured by the FIRAS instrument aboard COBE when it was compared to a very good BB calibrator. T=2.725±0.002 K (E. Wright) (Following E. Wright s (From CMB M. review Plionis paper) notes)

5 CMB spectrum a 4σ /c = Jm -3 K 4 a scale factor (From M. Georganopoulos lecture lib

6 CMB spectrum: z evolution (From M. Georganopoulos lecture lib

7 CMB spectrum: z evolution The almost perfect BB shape of the CMB backs up the expansion of the Universe, and the existence of a hotter earlier universe. If the the CMB were just a tired relic light: n γ (z=0)=(1+z e ) 3 B ν (T e ) but FIRAS imposes that the factor in front of B ν (T e ) is 1 with a precission better than Hence (1+z e )=1±1x10-4 z e < and opaque from that onwards. But we have sources at z~4! So this is not a possibility. If the steady model were correct, there would be no evolution. Today we see CMB + FIR radiation from stars and galaxies. Energy added between 1 month and a few thousand yrs after BB will produce I BE (ν,t) = 2πν 3 1 c 2 exp(hν /kt + µ) 1 but there are no deviations to the BB spectrum (Following E. Wright s CMB review paper)

8 Photon/baryon ratio (From M. Georganopoulos lecture lib)

9 Photon/baryon ratio Ω B /Ω γ 1000, n γ /n B 10 9 (From M. Georganopoulos lecture lib)

10 CMB origin (From M. Georganopoulos lecture lib

11 CMB origin (From M. Georganopoulos lecture lib

12 CMB origin (From M. Georganopoulos lecture lib)

13 CMB origin: recombination X n e /n B = n e /(n H + n p ) (From M. Georganopoulos lecture lib)

14 CMB origin: decoupling (From M. Georganopoulos lecture lib)

15 CMB origin: decoupling (From M. Georganopoulos lecture lib)

16 Radiation era We have that ρ M R -3 ρ rad R -4 There must be a z at which ρ M = ρ rad Taking into account that nucleosynthesis predicts n ν =0.68 n γ, then Ω rad =4.2 x 10-5 h z eq = 23900Ω m h 2 z eq 3100 (From M. Plionis notes or Peacock 1999)

17 CMB spectrum: dipole anisotropy Dipole anisotropy in COBE data can be explained as a Doppler effect between the frame of reference of the solar system and that at rest with the observable CMB. ν'= γ(1 β cosθ)ν, with β v /c and γ 1/ 1 β 2 T(θ) = T 0 /γ(1 β cosθ) T 0 + T 0 β cosθ A fit to the image T 0 β=3353±24µk And with T 0 =2.735K v sun v CMB = 369 ± 3 km s 1 Taking into account the movement around the MW, and the movement of the LG towards (l,b) (277 o, 30 o ) Signature of local attractors. -1 v LG v 620 ± 45 km s CMB (Following E. Wright s CMB review paper)

18 CMB spectrum: removing the galaxy Planck: 30 to 857 GHz image of the CMB after dipole subtraction. The galaxy emission is dominated by dust

19 CMB spectrum: removing the galaxy Cosmic Background Explorer COBE (1992): T/T = 10 5

20 CMB spectrum: removing the galaxy WMAP full sky view Graphics from WMAP website

21 CMB spectrum: removing the galaxy Planck s full sky view Graphics from WMAP website

C(θ) = 1 (2l +1) C l P l (cosθ) Which are related by where P 4π l are Legendre l polynomials of order l.

22 CMB spectrum: statistical properties T(l,b) can be fully specified by either the angular correlation function C(θ) or its Legendre transformation, the angular power spectrum C l. C(θ) = 1 (2l +1) C l P l (cosθ) Which are related by where P 4π l are Legendre l polynomials of order l. A term C l is a measure of angular fluctuations on the angular scale θ~180 o /l. In order to have equal power for all scales the spherical harmonics impose C l = cte/l(l+1).if the sky had equal power on all scales lc l (l+1) Graphics should be from a constant. WMAP website

23 CMB spectrum: power spectrum Graphics from WMAP website (From M. Georganopoulos lecture lib)

CMB spectrum: power spectrum l First peak had already been constrained by an array of 1992-2000 missions, and

24 CMB spectrum: power spectrum l First peak had already been constrained by an array of missions, and sampled in its full amplitude by Boomerang (1998) & Maxima (2000) Graphics from WMAP website (Hu & Dodelson 2002)

25 CMB spectrum: power spectrum Graphics from WMAP website (Ade et al. 2013)

26 CMB spectrum: power spectrum Graphics from WMAP website (From Hu s webpage)

27 CMB spectrum: power spectrum Graphics from WMAP website (From M. Georganopoulos lecture lib)

28 CMB spectrum: power spectrum Graphics from WMAP website (From M. Georganopoulos lecture lib)

29 CMB spectrum: power spectrum θ>θ H Graphics from WMAP website (From M. Georganopoulos lecture lib)

30 CMB spectrum: power spectrum θ<θ H Graphic by Wayne Hu, Graphics from WMAP website (From M. Georganopoulos lecture lib)

31 CMB spectrum: 1st peak of power spectrum Graphics from WMAP website (From M. Georganopoulos lecture lib)

32 CMB spectrum: 1st peak of power spectrum Graphics from WMAP website (From M. Georganopoulos lecture lib)

33 CMB spectrum: cosmic dependences Varied around a fidutial model Ω tot =1, Ω Λ =0.65, Ω B =0.02h -2, Ω m =0.147h -2, n=1, z ri =0, E=0 Graphics from WMAP website (Hu & Dodelson 2002)

34 CMB spectrum: cosmic dependences Age of Universe Ω m h 2 Ω m +Ω Λ Ω b h 2 z re n s

35 Planck spectrum: precission cosmology (Ade et al. 2013)

36 WMAP spectrum: precission cosmology (Spergel et al. 2006)

37 Planck spectrum: precission cosmology (Ade et al. 2013)

John Mather Visit Nobel Prize in Physics 2006 for Cosmic Microwave Background measurements

John Mather Visit Nobel Prize in Physics 006 for Cosmic Microwave Background measurements NEXT WEEK Wednesday :0-:00 BPS 00 BS session with astro students & faculty. Wednesday 8PM BPS 0 (refreshments at