2012

CMB at 2x2 order: the dissipation of primordial acoustic waves and the observable part of the associated energy release

Chluba, Jens, Khatri, Rishi, Sunyaev, Rashid A.

Understand

Silk damping of primordial small-scale perturbations in the photon-baryon fluid due to diffusion of photons inevitably creates spectral distortions in the CMB.

  • With the proposed CMB experiment PIXIE it might become possible to measure these distortions and thereby constrain the primordial power spectrum at comoving wavenumbers 50 Mpc^{-1} < k < 10^4 Mpc^{-1}.
  • Since primordial fluctuations in the CMB on these scales are completely erased by Silk damping, these distortions may provide the only way to shed light on otherwise unobservable aspects of inflationary physics.
  • A consistent treatment of the primordial dissipation problem requires going to second order in perturbation theory, while thermalization of these distortions necessitates consideration of second order in Compton scattering energy transfer.

Reading the bibliography…