2008A&A...492..657R


C.D.S. - SIMBAD4 rel 1.7 - 2020.07.06CEST05:41:40

2008A&A...492..657R - Astronomy and Astrophysics, volume 492, 657-673 (2008/12-4)

Poincare dodecahedral space parameter estimates.

ROUKEMA B.F., BULINSKI Z. and GAUDIN N.E.

Abstract (from CDS):

Several studies have proposed that the preferred model of the comoving spatial 3-hypersurface of the Universe may be a Poincare dodecahedral space (PDS) rather than a simply connected, infinite, flat space. Here, we aim to improve the surface of last scattering (SLS) optimal cross-correlation method and apply this to observational data and simulations. For a given ``generalised'' PDS orientation, we analytically derive the formulae required to exclude points on the sky that cannot be members of close SLS-SLS cross-pairs. These enable more efficient pair selection without sacrificing the uniformity of the underlying selection process. For a sufficiently small matched circle size α and a fixed number of randomly placed points selected for a cross-correlation estimate, the calculation time is decreased and the number of pairs per separation bin is increased. Using this faster method, and including the smallest separation bin when testing correlations, (i) we recalculate Monte Carlo Markov Chains (MCMC) on the five-year Wilkinson Microwave Anisotropy Probe (WMAP) data; and (ii) we seek PDS solutions in a small number of Gaussian random fluctuation (GRF) simulations in order to further explore the statistical significance of the PDS hypothesis. For 5°<α<60°, a calculation speed-up of 3-10 is obtained. (i) The best estimates of the PDS parameters for the five-year WMAP data are similar to those for the three-year data; (ii) comparison of the optimal solutions found by the MCMC chains in the observational map to those found in the simulated maps yields a slightly stronger rejection of the simply connected model using α rather than the twist angle φ. The best estimate of α implies that, given a large-scale auto-correlation as weak as that observed, the PDS-like cross-correlation signal in the WMAP data is expected with a probability of less than about 10%. The expected distribution of φ from the GRF simulations is not uniform on [-π,π]. Using this faster algorithm, we find that the previous PDS parameter estimates are stable to the update to five-year WMAP data. Moreover, for an infinite, flat, cosmic concordance model with Gaussian random fluctuations, the chance of finding both (a) a large-scale auto-correlation as weak as observed; and (b) a PDS-like signal similar to what is observed is less than about 0.015% to 1.25%.

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Journal keyword(s): cosmology: cosmological parameters - cosmology: observations - cosmology: theory

Simbad objects: 1

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Number of rows : 1

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2020
#notes
1 NAME NGP reg 12 51 26.275 +27 07 41.70           ~ 1020 0

    Equat.    Gal    SGal    Ecl

C.D.S. - SIMBAD4 rel 1.7 - 2020.07.06CEST05:41:40

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    • B : 0.01-0.1" + 2MASS, Tyc
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12 51 26.275 +27 07 41.70 [ ] D ~
Syntax of coordinates is : "ra dec (wtype) [error ellipse] quality bibcode" :
  • ra dec : right ascension and declination (unit and frame defined according to your Output Options)
    Grey values are increasing the original precision due to the computation of frame transformations
  • (wtype) : wavelength class for the origin of the coordinates (Rad, mm, IR, Optical, UV, Xray, Gam)
  • [error ellipse] : measurement uncertainty, on (ra,dec) if the positional angle is 90 degrees, on (majaxis,minaxis) otherwise (in mas at defined epoch in the original catalogue),
    position angle (in degrees North celestial pole to East)
  • quality : flag of quality
    • E ≥ 10"
    • D : 1-10" (and some old data)
    • C : 0.1-1"
    • B : 0.01-0.1" + 2MASS, Tyc
    • A : VLBI, Hipparcos
  • bibcode : bibcode of the coordinates reference
FK4 coord. (ep=B1950 eq=1950) :
12 48 59.999 +27 23 59.81 [ ]
Syntax of coordinates is : "ra dec (wtype) [error ellipse] quality bibcode" :
  • ra dec : right ascension and declination (unit and frame defined according to your Output Options)
    Grey values are increasing the original precision due to the computation of frame transformations
  • (wtype) : wavelength class for the origin of the coordinates (Rad, mm, IR, Optical, UV, Xray, Gam)
  • [error ellipse] : measurement uncertainty, on (ra,dec) if the positional angle is 90 degrees, on (majaxis,minaxis) otherwise (in mas at defined epoch in the original catalogue),
    position angle (in degrees North celestial pole to East)
  • quality : flag of quality
    • E ≥ 10"
    • D : 1-10" (and some old data)
    • C : 0.1-1"
    • B : 0.01-0.1" + 2MASS, Tyc
    • A : VLBI, Hipparcos
  • bibcode : bibcode of the coordinates reference
Gal coord. (ep=J2000) :
213.216840 +89.999999 [ ]
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NAME NGP NAME North Galactic Pole [SFD98] J1251+2708

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2020.07.06-05:41:40

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