### Abstract

We measure the angular power spectrum of the Wilkinson Microwave Anisotropy Probe (WMAP) first-year temperature anisotropy maps. We use the Spatially Inhomogeneous Correlation Estimator (SpICE) to estimate C_{l}'s for multipoles l = 2-900 from all possible cross-correlation channels. Except for the map-making stage, our measurements provide an independent analysis of that by G. Hinshaw et al. Despite the different methods used, there is virtually no difference between the two measurements for l ≲ 700; the highest l's are still compatible within 1 σ errors. We use a novel intrabin variance method to constrain C_{l} errors in a model-independent way. Simulations show that our implementation of the technique is unbiased within 1% for l ≲ 100. When applied to WMAP data, the intrabin variance estimator yields diagonal errors ∼10% larger than those reported by the WMAP team for 100 <l <450. This translates into a 2.4 sigma; detection of systematics, since no difference is expected between the SpICE and the WMAP team estimator window functions in this multipole range. With our measurement of the C _{l}'s and errors, we get a X^{2} per degree of freedom (dof) of 1.042 for a best-fit ACDM model, which has a 14% probability, whereas the WMAP team obtained X^{2}/dof = 1.066, which has a 5% probability. We assess the impact of our results on cosmological parameters using Markov chain Monte Carlo simulations. From WMAP data alone, assuming spatially flat power-law ACDM models, we obtain the reionization optical depth τ = 0.145 ± 0.067, spectral index n_{s} = 0.99 ± 0.04, Hubble constant h = 0.67 ± 0.05, baryon density Ω_{b}h^{2} = 0.0218 ± 0.0014, cold dark matter density Ω_{CDM}h^{2} = 0.122 ± 0.018, and σ_{8} = 0.92 ± 0.12, consistent with a reionization redshift z_{re} = 16 ± 5 (68% CL).

Original language | English |
---|---|

Journal | Astrophysical Journal |

Volume | 617 |

Issue number | 2 II |

DOIs | |

Publication status | Published - Dec 20 2004 |

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### Keywords

- Cosmic microwave background
- Cosmology: theory
- Methods: statistical

### ASJC Scopus subject areas

- Space and Planetary Science
- Nuclear and High Energy Physics

### Cite this

**The angular power spectrum of the first-year Wilkinson Microwave Anisotropy Probe data reanalyzed.** / Fosalba, Pablo; Szapudi, I.

Research output: Contribution to journal › Article

*Astrophysical Journal*, vol. 617, no. 2 II. https://doi.org/10.1086/427234

}

TY - JOUR

T1 - The angular power spectrum of the first-year Wilkinson Microwave Anisotropy Probe data reanalyzed

AU - Fosalba, Pablo

AU - Szapudi, I.

PY - 2004/12/20

Y1 - 2004/12/20

N2 - We measure the angular power spectrum of the Wilkinson Microwave Anisotropy Probe (WMAP) first-year temperature anisotropy maps. We use the Spatially Inhomogeneous Correlation Estimator (SpICE) to estimate Cl's for multipoles l = 2-900 from all possible cross-correlation channels. Except for the map-making stage, our measurements provide an independent analysis of that by G. Hinshaw et al. Despite the different methods used, there is virtually no difference between the two measurements for l ≲ 700; the highest l's are still compatible within 1 σ errors. We use a novel intrabin variance method to constrain Cl errors in a model-independent way. Simulations show that our implementation of the technique is unbiased within 1% for l ≲ 100. When applied to WMAP data, the intrabin variance estimator yields diagonal errors ∼10% larger than those reported by the WMAP team for 100 l's and errors, we get a X2 per degree of freedom (dof) of 1.042 for a best-fit ACDM model, which has a 14% probability, whereas the WMAP team obtained X2/dof = 1.066, which has a 5% probability. We assess the impact of our results on cosmological parameters using Markov chain Monte Carlo simulations. From WMAP data alone, assuming spatially flat power-law ACDM models, we obtain the reionization optical depth τ = 0.145 ± 0.067, spectral index ns = 0.99 ± 0.04, Hubble constant h = 0.67 ± 0.05, baryon density Ωbh2 = 0.0218 ± 0.0014, cold dark matter density ΩCDMh2 = 0.122 ± 0.018, and σ8 = 0.92 ± 0.12, consistent with a reionization redshift zre = 16 ± 5 (68% CL).

AB - We measure the angular power spectrum of the Wilkinson Microwave Anisotropy Probe (WMAP) first-year temperature anisotropy maps. We use the Spatially Inhomogeneous Correlation Estimator (SpICE) to estimate Cl's for multipoles l = 2-900 from all possible cross-correlation channels. Except for the map-making stage, our measurements provide an independent analysis of that by G. Hinshaw et al. Despite the different methods used, there is virtually no difference between the two measurements for l ≲ 700; the highest l's are still compatible within 1 σ errors. We use a novel intrabin variance method to constrain Cl errors in a model-independent way. Simulations show that our implementation of the technique is unbiased within 1% for l ≲ 100. When applied to WMAP data, the intrabin variance estimator yields diagonal errors ∼10% larger than those reported by the WMAP team for 100 l's and errors, we get a X2 per degree of freedom (dof) of 1.042 for a best-fit ACDM model, which has a 14% probability, whereas the WMAP team obtained X2/dof = 1.066, which has a 5% probability. We assess the impact of our results on cosmological parameters using Markov chain Monte Carlo simulations. From WMAP data alone, assuming spatially flat power-law ACDM models, we obtain the reionization optical depth τ = 0.145 ± 0.067, spectral index ns = 0.99 ± 0.04, Hubble constant h = 0.67 ± 0.05, baryon density Ωbh2 = 0.0218 ± 0.0014, cold dark matter density ΩCDMh2 = 0.122 ± 0.018, and σ8 = 0.92 ± 0.12, consistent with a reionization redshift zre = 16 ± 5 (68% CL).

KW - Cosmic microwave background

KW - Cosmology: theory

KW - Methods: statistical

UR - http://www.scopus.com/inward/record.url?scp=13944254103&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=13944254103&partnerID=8YFLogxK

U2 - 10.1086/427234

DO - 10.1086/427234

M3 - Article

AN - SCOPUS:13944254103

VL - 617

JO - Astrophysical Journal

JF - Astrophysical Journal

SN - 0004-637X

IS - 2 II

ER -