1996/02/29 by Wayne Hu, Martin White · 3 citations
Earth and Planetary Sciences · Physics and Astronomy · #Cosmology and Gravitation Theories #Geophysics and Gravity Measurements #Scientific Research and Discoveries #astro-ph
paper · pdf · doi:10.1086/177951
published as Astrophys.J.471:30-51,1996 · 45pg. aaspp4, 14 figs. minor changes reflect published version; supporting material at http://www.sns.ias.edu/~whu
arxiv created 1996/08/15 · openalex publication_date 1996/11/01 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/31
We study the uniqueness and robustness of acoustic signatures in the cosmic microwave background by allowing for the possibility that they are generated by some as yet unknown source of gravitational perturbations. The acoustic pattern of peak locations and relative heights predicted by the standard inflationary cold dark matter model is essentially unique, and its confirrmation would have deep implications for the causal structure of the early universe. A generic pattern for isocurvature initial conditions arises due to backreaction effects but is not robust to exotic source behavior inside the horizon. If present, the acoustic pattern contains unambiguous information on the curvature of the universe even in the general case. By classifying the behavior of the unknown source, we determine the minimal observations necessary for robust constraints on the curvature. The diffusion damping scale provides an entirely model-independent cornerstone upon which to build such a measurement. The peak spacing, if regular, supplies a precision test.