2017/08/15 by Niayesh Afshordi, Matthew C. Johnson
Physics and Astronomy · #Amplitude #Anisotropy #Astronomy #Astrophysics #Cosmic microwave background #Cosmic variance #Cosmological perturbation theory #Cosmology #Cosmology and Gravitation Theories #Dark Matter and Cosmic Phenomena #Dark energy #Galaxies: Formation, Evolution, Phenomena #Horizon #Metric expansion of space #Observable #Particle horizon #Physics #Quantum mechanics #Spectral density #astro-ph.CO #gr-qc #hep-th
paper · pdf · doi:10.1103/physrevd.98.023541
published as Phys. Rev. D 98, 023541 (2018) · 11 pages, 4 figures. Comments are welcome
arxiv created 2017/08/15 · openalex publication_date 2018/07/31 · arxiv updated 2018/08/08 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/06
We introduce a new family of primordial cosmological perturbations that are not described by traditional power spectra. At the linear level, these perturbations live in the kernel of the spatial Laplacian operator, and thus we call them cosmological zero modes. We compute the cosmic microwave background temperature and polarization anisotropy induced by these modes and forecast their detection sensitivity using a cosmic-variance limited experiment. In particular, we consider two configurations for the zero modes: The first configuration consists of stochastic metric perturbations described by white noise on a ``holographic screen'' located at our cosmological horizon. The amplitude of the power spectrum of this white noise can be constrained to be \ensuremath\lesssim9\ifmmode×\else\texttimes\fi10^\ensuremath-14. The second configuration is a primordial monopole beyond our cosmological horizon. We show that such a monopole, with ``charge'' Q, can be detected in the cosmic microwave background sky up to a distance of 11.6Q1/4\ifmmode×\else\texttimes\fihorizon radius (or 160Q1/4 Gpc). More generally, observational probes of cosmological zero modes can shed light on nonperturbative phenomena in the primordial Universe, beyond our observable horizon.