### Abstract

We examine how the statistics of the quadrupoles of (projected) cluster masses can discriminate between flat cold dark matter (ΛCDM) universes with or without a cosmological constant term. Even in the era of high-precision cosmology that cosmic microwave background experiments should soon open, it is important to devise self-consistent tests of cosmogonic theories tuned at the matter radiation decoupling epoch using data from the nonlinear evolved universe. We build cluster catalogs from two large-volume simulations of a "tilted" cold dark matter (TCDM) model and a ΛCDM model with cosmic density parameter Ω_{m} = 0.35 and cosmological constant contribution Ω_{Λ} = 0.65. From the projected mass distribution of the clusters we work out the quadrupoles Q and examine their dependence on cluster mass and the cosmological model. We find that TCDM clusters have systematically larger quadrupoles than their ΛCDM counterpart. The effect is mass dependent: massive clusters (M ≳ 10 ^{15} h^{-1} M_{⊙}) have quadrupoles differing by more than 30% in the two models, while for M ≲ 4 × 10^{14} h^{-1} M_{⊙} the difference rapidly drops to ∼1%. Performing a Kolmogorov-Smirnov D-statistic (K-S) test of the Q distributions, we estimate that using just the 15 most massive clusters in the simulation volume (360 h^{-1} Mpc a side), we can discriminate between TCDM and ΛCDM at a confidence level better than 99.9%. In the volume probed by existing observations, there are potentially several hundred clusters with masses above the threshold for which the differences in the quadrupoles become relevant. Should weak lensing data become available for this whole set, a quadrupole analysis may be expected to discriminate among different values of Λ.

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

Pages (from-to) | 1-7 |

Number of pages | 7 |

Journal | Astrophysical Journal |

Volume | 564 |

Issue number | 1 I |

DOIs | |

State | Published - Jan 1 2002 |

### Fingerprint

### Keywords

- Cosmology: theory
- Dark matter
- Galaxies: clusters: general
- Galaxies: halos
- Large-scale structure of universe
- Methods: numerical

### ASJC Scopus subject areas

- Astronomy and Astrophysics
- Space and Planetary Science

### Cite this

*Astrophysical Journal*,

*564*(1 I), 1-7. https://doi.org/10.1086/324185

**Constraining Λ using cluster quadrupoles.** / Maccio, Andrea; Gardini, Alessandro; Ghigna, Sebastiano; Bonometto, Silvio.

Research output: Contribution to journal › Article

*Astrophysical Journal*, vol. 564, no. 1 I, pp. 1-7. https://doi.org/10.1086/324185

}

TY - JOUR

T1 - Constraining Λ using cluster quadrupoles

AU - Maccio, Andrea

AU - Gardini, Alessandro

AU - Ghigna, Sebastiano

AU - Bonometto, Silvio

PY - 2002/1/1

Y1 - 2002/1/1

N2 - We examine how the statistics of the quadrupoles of (projected) cluster masses can discriminate between flat cold dark matter (ΛCDM) universes with or without a cosmological constant term. Even in the era of high-precision cosmology that cosmic microwave background experiments should soon open, it is important to devise self-consistent tests of cosmogonic theories tuned at the matter radiation decoupling epoch using data from the nonlinear evolved universe. We build cluster catalogs from two large-volume simulations of a "tilted" cold dark matter (TCDM) model and a ΛCDM model with cosmic density parameter Ωm = 0.35 and cosmological constant contribution ΩΛ = 0.65. From the projected mass distribution of the clusters we work out the quadrupoles Q and examine their dependence on cluster mass and the cosmological model. We find that TCDM clusters have systematically larger quadrupoles than their ΛCDM counterpart. The effect is mass dependent: massive clusters (M ≳ 10 15 h-1 M⊙) have quadrupoles differing by more than 30% in the two models, while for M ≲ 4 × 1014 h-1 M⊙ the difference rapidly drops to ∼1%. Performing a Kolmogorov-Smirnov D-statistic (K-S) test of the Q distributions, we estimate that using just the 15 most massive clusters in the simulation volume (360 h-1 Mpc a side), we can discriminate between TCDM and ΛCDM at a confidence level better than 99.9%. In the volume probed by existing observations, there are potentially several hundred clusters with masses above the threshold for which the differences in the quadrupoles become relevant. Should weak lensing data become available for this whole set, a quadrupole analysis may be expected to discriminate among different values of Λ.

AB - We examine how the statistics of the quadrupoles of (projected) cluster masses can discriminate between flat cold dark matter (ΛCDM) universes with or without a cosmological constant term. Even in the era of high-precision cosmology that cosmic microwave background experiments should soon open, it is important to devise self-consistent tests of cosmogonic theories tuned at the matter radiation decoupling epoch using data from the nonlinear evolved universe. We build cluster catalogs from two large-volume simulations of a "tilted" cold dark matter (TCDM) model and a ΛCDM model with cosmic density parameter Ωm = 0.35 and cosmological constant contribution ΩΛ = 0.65. From the projected mass distribution of the clusters we work out the quadrupoles Q and examine their dependence on cluster mass and the cosmological model. We find that TCDM clusters have systematically larger quadrupoles than their ΛCDM counterpart. The effect is mass dependent: massive clusters (M ≳ 10 15 h-1 M⊙) have quadrupoles differing by more than 30% in the two models, while for M ≲ 4 × 1014 h-1 M⊙ the difference rapidly drops to ∼1%. Performing a Kolmogorov-Smirnov D-statistic (K-S) test of the Q distributions, we estimate that using just the 15 most massive clusters in the simulation volume (360 h-1 Mpc a side), we can discriminate between TCDM and ΛCDM at a confidence level better than 99.9%. In the volume probed by existing observations, there are potentially several hundred clusters with masses above the threshold for which the differences in the quadrupoles become relevant. Should weak lensing data become available for this whole set, a quadrupole analysis may be expected to discriminate among different values of Λ.

KW - Cosmology: theory

KW - Dark matter

KW - Galaxies: clusters: general

KW - Galaxies: halos

KW - Large-scale structure of universe

KW - Methods: numerical

UR - http://www.scopus.com/inward/record.url?scp=0041731825&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0041731825&partnerID=8YFLogxK

U2 - 10.1086/324185

DO - 10.1086/324185

M3 - Article

AN - SCOPUS:0041731825

VL - 564

SP - 1

EP - 7

JO - Astrophysical Journal

JF - Astrophysical Journal

SN - 0004-637X

IS - 1 I

ER -