2008/08/31 by J. P. Zibin, Douglas Scott, D. Scott · 2 citations
Physics and Astronomy · #Adiabatic process #Anisotropy #Astrophysics #COSMIC cancer database #Cosmic microwave background #Cosmology #Cosmology and Gravitation Theories #Dark energy #Dipole #Galaxies: Formation, Evolution, Phenomena #Hubble volume #Hubble's law #Magnetic monopole #Physics #Quantum mechanics #Radio Astronomy Observations and Technology #Theoretical physics #astro-ph
paper · pdf · doi:10.1103/physrevd.78.123529
published as Phys.Rev.D78:123529,2008 · 17 pages, 5 figures; minor changes; version accepted to Phys. Rev. D
arxiv created 2008/12/21 · openalex publication_date 2008/12/24 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
We provide a new derivation of the anisotropies of the cosmic microwave background (CMB), and find an exact expression that can be readily expanded perturbatively. Close attention is paid to gauge issues, with the motivation to examine the effect of super-Hubble modes on the CMB. We calculate a transfer function that encodes the behavior of the dipole, and examine its long-wavelength behavior. We show that contributions to the dipole from adiabatic super-Hubble modes are strongly suppressed, even in the presence of a cosmological constant, contrary to claims in the literature. We also introduce a naturally defined CMB monopole, which exhibits closely analogous long-wavelength behavior. We discuss the geometrical origin of this super-Hubble suppression, pointing out that it is a simple reflection of adiabaticity, and hence argue that it will occur regardless of the matter content.