### Abstract

We test the homogeneity of the universe at z ∼ 0.3 with the luminous red galaxy (LRG) spectroscopic sample of the Sloan Digital Sky Survey. First, the mean number N(R) of LRGs within completely surveyed LRG-centered spheres of comoving radius R is shown to be proportional to R^{3} at radii greater than R ∼ 70 h^{-1} Mpc. The test has the virtue that it does not rely on the assumption that the LRG sample has a finite mean density; its results show, however, that there is such a mean density. Second, the survey sky area is divided into 10 disjoint solid angular regions, and the fractional rms density variations of the LRG sample in the redshift range 0.2 < z < 0.35 among these (∼2 × 10^{7} h^{-3} Mpc^{3}) regions is found to be 7% of the mean density. This variance is consistent with typical biased ACDM models and puts very strong constraints on the quality of SDSS photometric calibration.

Original language | English (US) |
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Pages (from-to) | 54-58 |

Number of pages | 5 |

Journal | Astrophysical Journal |

Volume | 624 |

Issue number | 1 I |

DOIs | |

State | Published - May 1 2005 |

### All Science Journal Classification (ASJC) codes

- Astronomy and Astrophysics
- Space and Planetary Science

### Keywords

- Cosmological parameters
- Cosmology: observations
- Galaxies: statistics
- Large-scale structure of universe
- Methods: statistical
- Surveys

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## Cite this

*Astrophysical Journal*,

*624*(1 I), 54-58. https://doi.org/10.1086/429084