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CMB acoustic peaks

CMB acoustic peaks

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CMB acoustic peaks

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  1. CMB acoustic peaks

  2. 3rd acoustic peak fluid compression in potential wells Potential fluctuations broken up by mode hill well time 2nd acoustic peak fluid compression in potential hills 1st acoustic peak fluid compression in potential wells

  3. CMB temperature fluctuations Three effects contribute to “relative” time dilation – spacing between wave crests changes “absolute” time dilation – the whole wave-train is delayed/advanced bulk fluid motion adds a line-of-sight velocity Doppler term Sachs-Wolfe effect Acoustic peaks

  4. Fluid oscillations:linear perturbation equation and solution

  5. p 2p 3p 4p k (fixed t) k (fixed t) p 2p 3p 4p Potential and Doppler terms; no baryons Potential hill compressions rarifactions potential doppler Potential well Sachs-Wolfe effect (small k, large scales)

  6. Add baryons

  7. Fluid oscillations in a single potential well Graphic – Wayne Hu

  8. Add baryons Baryon drag decreases the height of even-numbered peaks (2nd, 4th, etc.) compared to the odd numbered peaks (1st, 3rd, etc.) 3rd acoustic peak 1st acoustic peak doppler term is also enhanced, but not as much- doppler term is subdominant Potential well k (fixed t) p 2p 3p 4p 2nd peak

  9. WMAP 3 year data convert positive and negative temperature fluctuations to rms temperature fluctuations (take squares – all positive) 3D -> 2D projection effects and smearing of fluctuations on small angular scales damping envelope baryon drag