The signature of dark energy on the local Hubble flow

Andrea V. Macciò, Fabio Governato, Cathy Horellou

Research output: Contribution to journalArticlepeer-review


Using N-body simulations of flat, dark energy-dominated cosmologies, we show that galaxies around simulated binary systems resembling the Local Group (LG) have low peculiar velocities, in good agreement with observational data. We have compared results for LG-like systems selected from large, high-resolution simulations of three cosmologies: a λCDM model, a λWDM model with a 2-keV warm dark matter candidate, and a quintessence (QCDM) model with an equation-of-state parameter w = -0.6. The Hubble flow is significantly colder around LGs selected in a flat, λ-dominated cosmology than around LGs in open or critical models, showing that a dark energy component manifests itself on the scales of nearby galaxies, cooling galaxy peculiar motions. Flows in the λWDM and QCDM models are marginally colder than in the λCDM one. The results of our simulations have been compared to existing data and to a new data set of 28 nearby galaxies with robust distance measures (Cepheids and surface brightness fluctuations). The measured line-of-sight velocity dispersion is given by σH = (88 ± 20 kms-1) × (R/7 Mpc). The best agreement with observations is found for LGs selected in the λCDM cosmology in environments with -0.1 < δρ/ρ < 0.6 on scales of 7 Mpc, in agreement with existing observational estimates on the local matter density. These results provide new, independent evidence for the presence of dark energy on scales of a few megaparsecs, corroborating the evidence gathered from observations of distant objects and the early Universe.

Original languageEnglish (US)
Pages (from-to)941-948
Number of pages8
JournalMonthly Notices of the Royal Astronomical Society
Issue number3
StatePublished - May 21 2005


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

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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