### Abstract

The CMB has distinct peaks in both its temperature angular power spectrum (TT) and temperature-polarization cross-power spectrum (TE). From the WMAP data we find the first peak in the temperature spectrum at ℓ = 220.1 ± 0. 8 with an amplitude of 74.7 ± 0.5 μK; the first trough at ℓ = 411.7 ± 3.5 with an amplitude of 41.0 ± 0.5 μK; and the second peak at ℓ = 546 ± 10 with an amplitude of 48.8 ± 0.9 μK. The TE spectrum has an antipeak at ℓ = 137 ± 9 with a cross-power of -35 ± 9 μK^{2}, and a peak at ℓ = 329 ± 19 with cross-power 105 ± 18 μK^{2}. All uncertainties are 1 σ and include calibration and beam errors. An intuition for how the data determine the cosmological parameters may be gained by limiting one's attention to a subset of parameters and their effects on the peak characteristics. We interpret the peaks in the context of a flat adiabatic ΛCDM model with the goal of showing how the cosmic baryon density, Ω_{b}h ^{2}, matter density, Ω_{m}h^{2}, scalar index, n_{s}, and age of the universe are encoded in their positions and amplitudes. To this end, we introduce a new scaling relation for the TE antipeak-to-peak amplitude ratio and recompute known related scaling relations for the TT spectrum in light of the WMAP data. From the scaling relations, we show that WMAP's tight bound on Ω_{b}h^{2} is intimately linked to its robust detection of the first and second peaks of the TT spectrum.

Original language | English (US) |
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Pages (from-to) | 233-241 |

Number of pages | 9 |

Journal | Astrophysical Journal, Supplement Series |

Volume | 148 |

Issue number | 1 |

DOIs | |

State | Published - Sep 1 2003 |

### All Science Journal Classification (ASJC) codes

- Astronomy and Astrophysics
- Space and Planetary Science

### Keywords

- Cosmic microwave background
- Cosmological parameters
- Cosmology: observations
- Large-scale structure of universe

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## Cite this

*Astrophysical Journal, Supplement Series*,

*148*(1), 233-241. https://doi.org/10.1086/377224