### Abstract

Cosmic microwave background (CMB) anisotropies that result from quantum fluctuations during inflation are explored and the impact of their "cosmic variance" on the ability to use existing data to probe inflationary models is studied. We calculate the rms temperature fluctuation, and its cosmic variance, for a number of experiments and for models with primordial power spectra which range from n = 1/2 to 1. We find (1) cosmic variance obscures the information which can be extracted, so a comparison of the rms temperature fluctuation on small scales with the COBE result can fix n to only ≈ ±0.2 at best; (2) measurements of the rms fluctuation on 1° scales may not allow one to unambiguously infer the tensor contribution to the COBE anisotropy; and (3) comparison of this contribution with the predictions of inflation are ambiguous if the quadrupole anisotropy alone is utilized. We discuss means for minimizing the uncertainty due to cosmic variance in comparisons between experiments.

Original language | English (US) |
---|---|

Pages (from-to) | 535-543 |

Number of pages | 9 |

Journal | Astrophysical Journal |

Volume | 418 |

Issue number | 2 |

State | Published - Dec 1 1993 |

Externally published | Yes |

### Fingerprint

### Keywords

- Cosmic microwave background
- Cosmology: theory
- Early universe

### ASJC Scopus subject areas

- Space and Planetary Science

### Cite this

*Astrophysical Journal*,

*418*(2), 535-543.

**Cosmic variance in cosmic microwave background anisotropies : From 1° to COBE.** / White, Martin; Krauss, Lawrence; Silk, Joseph.

Research output: Contribution to journal › Article

*Astrophysical Journal*, vol. 418, no. 2, pp. 535-543.

}

TY - JOUR

T1 - Cosmic variance in cosmic microwave background anisotropies

T2 - From 1° to COBE

AU - White, Martin

AU - Krauss, Lawrence

AU - Silk, Joseph

PY - 1993/12/1

Y1 - 1993/12/1

N2 - Cosmic microwave background (CMB) anisotropies that result from quantum fluctuations during inflation are explored and the impact of their "cosmic variance" on the ability to use existing data to probe inflationary models is studied. We calculate the rms temperature fluctuation, and its cosmic variance, for a number of experiments and for models with primordial power spectra which range from n = 1/2 to 1. We find (1) cosmic variance obscures the information which can be extracted, so a comparison of the rms temperature fluctuation on small scales with the COBE result can fix n to only ≈ ±0.2 at best; (2) measurements of the rms fluctuation on 1° scales may not allow one to unambiguously infer the tensor contribution to the COBE anisotropy; and (3) comparison of this contribution with the predictions of inflation are ambiguous if the quadrupole anisotropy alone is utilized. We discuss means for minimizing the uncertainty due to cosmic variance in comparisons between experiments.

AB - Cosmic microwave background (CMB) anisotropies that result from quantum fluctuations during inflation are explored and the impact of their "cosmic variance" on the ability to use existing data to probe inflationary models is studied. We calculate the rms temperature fluctuation, and its cosmic variance, for a number of experiments and for models with primordial power spectra which range from n = 1/2 to 1. We find (1) cosmic variance obscures the information which can be extracted, so a comparison of the rms temperature fluctuation on small scales with the COBE result can fix n to only ≈ ±0.2 at best; (2) measurements of the rms fluctuation on 1° scales may not allow one to unambiguously infer the tensor contribution to the COBE anisotropy; and (3) comparison of this contribution with the predictions of inflation are ambiguous if the quadrupole anisotropy alone is utilized. We discuss means for minimizing the uncertainty due to cosmic variance in comparisons between experiments.

KW - Cosmic microwave background

KW - Cosmology: theory

KW - Early universe

UR - http://www.scopus.com/inward/record.url?scp=0011455399&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0011455399&partnerID=8YFLogxK

M3 - Article

AN - SCOPUS:0011455399

VL - 418

SP - 535

EP - 543

JO - Astrophysical Journal

JF - Astrophysical Journal

SN - 0004-637X

IS - 2

ER -