Cold dark matter and degree-scale cosmic microwave background anisotropy statistics after COBE

Górski, K. M.; Stompor, R.; Juszkiewicz, R.

doi:10.1086/186865

Cited by 24 publications

(21 citation statements)

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“…Given the mutual interdependence of the effects, the semi-analytic methods can only be taken so far, and numerical computation of spectra is the preferred method for this high precision era of CMB observations. There were many groups who developed codes to solve the perturbed Boltzmann-Einstein equations when dark matter was present prior to and following shortly after the COBE discovery (Bond 1996;Bond & Efstathiou 1984Crittenden et al 1993,b;Dodelson & Jubas 1994;Efstathiou & Bond 1986;Fukugita et al 1990;Gorski, Stompor & Juszkiewicz 1993;Gouda et al 1991;Knox 1995;Vittorio & Silk 1984, 1992. Most of these solved hierarchies of coupled multipole equations.…”

Section: Anisotropies From the Recombination Epochmentioning

confidence: 99%

Cosmological Parameters from Cosmic Background Imager Observations and Comparisons with BOOMERANG, DASI, and MAXIMA

Sievers

Bond

Cartwright

et al. 2003

ApJ

180

120

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We report on the cosmological parameters derived from observations with the Cosmic Background Imager (CBI), covering 40 square degrees and the multipole range 300 ℓ 3500. The angular scales probed by the CBI correspond to structures which cover the mass range from 10 14 M ⊙ to 10 17 M ⊙ , and the observations reveal, for the first time, the seeds that gave rise to clusters of galaxies. These unique, high-resolution observations also show damping in the power spectrum to ℓ ∼ 2000, which we interpret as due to the finite width of the photon-baryon decoupling region and the viscosity operating at decoupling. Because the observations extend to much higher ℓ the CBI results provide information complementary to that probed by the BOOMERANG, DASI, MAXIMA, and VSA experiments. When the CBI observations are used in combination with those from COBE-DMR we find evidence for a flat universe, Ω tot = 1.00 +0.11 −0.12 (1-σ), a power law index of primordial fluctuations, n s = 1.08 +0.11 −0.10 , and densities in cold dark matter, Ω cdm h 2 = 0.16 +0.08 −0.07 , and baryons, Ω b h 2 = 0.023 +0.016 −0.010 . With the addition of large scale structure priors the Ω cdm h 2 value is sharpened to 0.10 +0.04 −0.03 , and we find Ω Λ = 0.67 +0.10 −0.13 . In the ℓ < 1000 overlap region with the BOOMERANG, DASI, MAXIMA, and VSA experiments, the agreement between these four experiments is excellent, and we construct optimal power spectra in the CBI bands which demonstrate this agreement. We derive cosmological parameters for the combined CMB experiments and show that these parameter determinations are stable as we progress from the weak priors using only CMB observations and very broad restrictions on cosmic parameters, through the addition of information from large scale structure surveys, Hubble parameter determinations and Supernova-1a results. The combination of these with CMB observations gives a vacuum energy estimate of Ω Λ = 0.70 +0.05 −0.05 , a Hubble parameter h = 0.69 ± 0.04 and a cosmological age of 13.7 ± 0.2 Gyr. As the observations are pushed to higher multipoles no anomalies relative to standard models appear, and extremely good consistency is found between the cosmological parameters derived for the CBI observations over the range 610 < ℓ < 2000 and observations at lower ℓ.

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Section: Anisotropies From the Recombination Epochmentioning

confidence: 99%

Cosmological Parameters from Cosmic Background Imager Observations and Comparisons with BOOMERANG, DASI, and MAXIMA

Sievers

Bond

Cartwright

et al. 2003

ApJ

180

120

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“…Detailed numerical calculations of the Boltzmann equations have been carried out for many different models, e.g., the pioneering work of [10, 13,16,9,45,46], and the more recent treatments by [47][48][49][50][51][52][53][54][55][56][57][58][59][60][61]8] among others. The most comprehensive set of results to date are presented in [7].…”

Section: The Boltzmann Equationsmentioning

confidence: 99%

Effect of physical assumptions on the calculation of microwave background anisotropies

et al. 1995

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As the data on cosmic microwave background anisotropies improve and potential cosmological applications are realized, it will be increasingly important for theoretical calculations to be as accurate as possible. All modern calculations for inflationary-inspired fluctuations involve the numerical solution of coupled Boltzmann equations. There are many assumptions and choices to be made when carrying out such calculations. Here we go through each assumption in turn, pointing out the best selections to make in each case, and the level of inaccuracy expected through an incorrect choice. For example, neglecting the effects of neutrinos or polarization has a 10% effect. Varying input parameters such as the radiation temperature and helium fraction can have smaller, but noticeable effects. We also discuss a few issues which are more numerical, such as the k range and smoothing. Some short-cut methods for obtaining the anisotropy spectrum are also investigated, for example, free-streaming and tilt approximations; generally none of these are adequate a t the few % level. At the level of 1% it is important to consider somewhat baroque effects, such as helium recombination and even minimal amounts of reionization. At smaller angular scales there are secondary and higher-order effects which will ultimately have to be considered. Extracting information from the subsidiary acoustic peaks and the damping region of the anisotropy spectrum will be a n extremely challenging problem. However, given the real prospect of measuring just such information on the sky, it will be important to meet this challenge. In principle it will be possible to extract rather detailed information about reionization history, neutrino contribution, helium abundance, non-power-law initial conditions, etc.PACS nnmber(s): 98.70. Vc, 95.75.Pq, 9 8 . 8 0 . H~

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“…One proposal ) is to combine the COBE detection with measurements of the CMBR at the degree angular scale, as tested by the South Pole experiment (Gaier et al 1992;Schuster et al 1993). It has been claimed that these measurements are consistent with the COBE data for a scale-invariant power spectrum and the Cold Dark Matter (CDM) scenario; but the present accuracy and the inherent cosmic variance of the observations do not allow a precise determination of n (Dodelson & Jubas 1993;Bunn et al 1993; see however Gorski, Stompor & Juszkiewicz 1993).…”

Section: Introductionmentioning

confidence: 99%

Blue perturbation spectra from inflation

1994

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We investigate inflationary models leading to density perturbations with a spectral index $n>1$ (``blue spectra"). These perturbation spectra may be useful to simultaneously account for both the amount of ultra large-scale power required to fit cosmic microwave background anisotropies, such as those measured by COBE, and that required to give bulk motions and structures on the $\sim 50~h^{-1}$ Mpc scale.Comment: 12 pages, plain TE

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Cold dark matter and degree-scale cosmic microwave background anisotropy statistics after COBE

Cited by 24 publications

References 0 publications

Cosmological Parameters from Cosmic Background Imager Observations and Comparisons with BOOMERANG, DASI, and MAXIMA

Cosmological Parameters from Cosmic Background Imager Observations and Comparisons with BOOMERANG, DASI, and MAXIMA

Effect of physical assumptions on the calculation of microwave background anisotropies

Blue perturbation spectra from inflation

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