skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Cosmic microwave background anisotropy from nonlinear structures in accelerating universes

Abstract

We study the cosmic microwave background (CMB) anisotropy due to spherically symmetric nonlinear structures in flat universes with dust and a cosmological constant. By modeling a time-evolving spherical compensated void/lump by Lemaitre-Tolman-Bondi spacetimes, we numerically solve the null geodesic equations with the Einstein equations. We find that a nonlinear void redshifts the CMB photons that pass through it regardless of the distance to it. In contrast, a nonlinear lump blueshifts (or redshifts) the CMB photons if it is located near (or sufficiently far from) us. The present analysis comprehensively covers previous works based on a thin-shell approximation and a linear/second-order perturbation method and the effects of shell thickness and full nonlinearity. Our results indicate that, if quasilinear and large (> or approx.100 Mpc) voids/lumps would exist, they could be observed as cold or hot spots with temperature variance > or approx. 10{sup -5} K in the CMB sky.

Authors:
;  [1];  [2]
  1. Department of Education, Yamagata University, Yamagata 990-8560 (Japan)
  2. (Japan)
Publication Date:
OSTI Identifier:
21250818
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review. D, Particles Fields; Journal Volume: 78; Journal Issue: 6; Other Information: DOI: 10.1103/PhysRevD.78.063510; (c) 2008 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; 99 GENERAL AND MISCELLANEOUS//MATHEMATICS, COMPUTING, AND INFORMATION SCIENCE; ANISOTROPY; APPROXIMATIONS; COSMIC DUST; COSMOLOGICAL CONSTANT; DISTANCE; DISTURBANCES; EINSTEIN FIELD EQUATIONS; GEODESICS; HOT SPOTS; MAXIMUM PERMISSIBLE CONCENTRATION; NONLINEAR PROBLEMS; NUMERICAL SOLUTION; PERTURBATION THEORY; PHOTONS; RED SHIFT; RELICT RADIATION; SIMULATION; SPACE-TIME; SPHERICAL CONFIGURATION; UNIVERSE

Citation Formats

Sakai, Nobuyuki, Inoue, Kaiki Taro, and Department of Science and Engineering, Kinki University, Higashi-Osaka 577-8502. Cosmic microwave background anisotropy from nonlinear structures in accelerating universes. United States: N. p., 2008. Web. doi:10.1103/PHYSREVD.78.063510.
Sakai, Nobuyuki, Inoue, Kaiki Taro, & Department of Science and Engineering, Kinki University, Higashi-Osaka 577-8502. Cosmic microwave background anisotropy from nonlinear structures in accelerating universes. United States. doi:10.1103/PHYSREVD.78.063510.
Sakai, Nobuyuki, Inoue, Kaiki Taro, and Department of Science and Engineering, Kinki University, Higashi-Osaka 577-8502. Mon . "Cosmic microwave background anisotropy from nonlinear structures in accelerating universes". United States. doi:10.1103/PHYSREVD.78.063510.
@article{osti_21250818,
title = {Cosmic microwave background anisotropy from nonlinear structures in accelerating universes},
author = {Sakai, Nobuyuki and Inoue, Kaiki Taro and Department of Science and Engineering, Kinki University, Higashi-Osaka 577-8502},
abstractNote = {We study the cosmic microwave background (CMB) anisotropy due to spherically symmetric nonlinear structures in flat universes with dust and a cosmological constant. By modeling a time-evolving spherical compensated void/lump by Lemaitre-Tolman-Bondi spacetimes, we numerically solve the null geodesic equations with the Einstein equations. We find that a nonlinear void redshifts the CMB photons that pass through it regardless of the distance to it. In contrast, a nonlinear lump blueshifts (or redshifts) the CMB photons if it is located near (or sufficiently far from) us. The present analysis comprehensively covers previous works based on a thin-shell approximation and a linear/second-order perturbation method and the effects of shell thickness and full nonlinearity. Our results indicate that, if quasilinear and large (> or approx.100 Mpc) voids/lumps would exist, they could be observed as cold or hot spots with temperature variance > or approx. 10{sup -5} K in the CMB sky.},
doi = {10.1103/PHYSREVD.78.063510},
journal = {Physical Review. D, Particles Fields},
number = 6,
volume = 78,
place = {United States},
year = {Mon Sep 15 00:00:00 EDT 2008},
month = {Mon Sep 15 00:00:00 EDT 2008}
}
  • We compute the large-scale anisotropy of the cosmic background radiation due to the gravitational field of clumped matter in open, closed, and flat Friedmann universes. Formulas are derived for the mean-square angular fluctuation of the cosmic background radiation in terms of the two-point correlation function of matter. The results depend importantly on whether or not the matter perturbations locally satisfy the integral constraints which express local conservation of energy and momentum, and we discuss these two possibilities. We examine the behavior as spatial curvature goes to zero.
  • We investigate the effect of wiggly cosmic strings on the cosmic microwave background radiation anisotropy and matter power spectrum by modifying the string network model used by Albrecht {ital et al.} We employ the wiggly equation of state for strings and the one-scale model for the cosmological evolution of certain network characteristics. For the same choice of simulation parameters we compare the results with and without including wiggliness in the model and find that wiggliness together with the accompanying low string velocities leads to a significant peak in the microwave background anisotropy and to an enhancement in the matter powermore » spectrum. For the cosmologies we have investigated (standard CDM and CDM plus a cosmological constant), and within the limitations of our modeling of the string network, the anisotropy is in reasonable agreement with current observations but the COBE normalized amplitude of density perturbations is lower than what the data suggest. In the case of a cosmological constant and CDM model, a bias factor of about 2 is required. {copyright} {ital 1999} {ital The American Physical Society}« less
  • We use a frequentist statistical approach to set confidence intervals on the values of cosmological parameters using the MAXIMA-1 and COBE measurements of the angular power spectrum of the cosmic microwave background. We define a Deltachi (2) statistic, simulate the measurements of MAXIMA-1 and COBE, determine the probability distribution of the statistic, and use it and the data to set confidence intervals on several cosmological parameters. We compare the frequentist confidence intervals with Bayesian credible regions. The frequentist and Bayesian approaches give best estimates for the parameters that agree within 15 per cent, and confidence interval widths that agree tomore » within 30 per cent. The results also suggest that a frequentist analysis gives slightly broader confidence intervals than a Bayesian analysis. The frequentist analysis gives values of Omega = 0.89(-0.19)(+0.26), Omega(B) h(2) =0.026(-0.011)(+0.020) and n = 1.02(-0.10)(+0.31), and the Bayesian analysis gives values of Omega = 0.98(-0.19)(+0.14) Omega(B) h(2) =0.029(-0.010)(+0.015), and n = 1.18(-0.23)(+0.10), all at the 95 per cent confidence level.« less
  • A self-consistent method is presented for comparing theoretical predictions of and observational upper limits on CMB anisotropy. New bounds on CDM cosmologies set by the UCSB South Pole experiment on the 1 deg angular scale are presented. An upper limit of 4.0 x 10 to the -5th is placed on the rms differential temperature anisotropy to a 95 percent confidence level and a power of the test beta = 55 percent. A lower limit of about 0.6/b is placed on the density parameter of cold dark matter universes with greater than about 3 percent baryon abundance and a Hubble constantmore » of 50 km/s/Mpc, where b is the bias factor, equal to unity only if light traces mass. 22 refs.« less
  • The quadrupole anisotropy of the cosmic microwave background expected in a variety of open universe models is evaluated by taking full account of contributions from both the generalized Sachs-Wolfe effect and intrinsic photon fluctuations at decoupling. Comparing the results with the observed upper limit of the quadrupole anisotropy, constraints on open universe models are derived. It is concluded that, even if the most conservative attitude is adopted, both hot and cold dark matter models with h = 0.5, Omega(0) not greater than 0.2 and all pure baryonic models with Omega(0) not greater than 0.2 are excluded if the initial densitymore » spectrum has the power-law index n not greater than 1, while both hot and cold dark matter models with h = 1.0, Omega(0) not greater than 0.2, and n not greater than 1 are marginally consistent with the observed upper limit of the quadrupole if one allows possible ambiguities in the normalization of the perturbation amplitudes. 29 refs.« less