A neutrino model fit to the CMB power spectrum

Published

Journal Article

© 2014 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society. The standard cosmological model, Λ cold dark matter (ΛCDM), provides an excellent fit to cosmic microwave background (CMB) data. However, the model has well-known problems. For example, the cosmological constant, Λ, is fine-tuned to 1 part in 10100 and the CDM particle is not yet detected in the laboratory. Shanks previously investigated a model which assumed neither exotic particles nor a cosmological constant but instead postulated a low Hubble constant (H0) to allow a baryon density compatible with inflation and zero spatial curvature. However, recent Planck results make it more difficult to reconcile such a model with CMB power spectra. Here, we relax the previous assumptions to assess the effects of assuming three active neutrinos of mass ≈5 eV. If we assume a low H0 ≈ 45 km s-1 Mpc-1 then, compared to the previous purely baryonic model, we find a significantly improved fit to the first three peaks of the Planck power spectrum. Nevertheless, the goodness of fit is still significantly worse than for ΛCDM and would require appeal to unknown systematic effects for the fit ever to be considered acceptable. A further serious problem is that the amplitude of fluctuations is low (σ8 ≈ 0.2), making it difficult to form galaxies by the present day. This might then require seeds, perhaps from a primordial magnetic field, to be invoked for galaxy formation. These and other problems demonstrate the difficulties faced by models other than ΛCDM in fitting ever more precise cosmological data.

Full Text

Duke Authors

Cited Authors

  • Shanks, T; Johnson, RWF; Schewtschenko, JA; Whitbourn, JR

Published Date

  • January 1, 2014

Published In

Volume / Issue

  • 445 / 3

Start / End Page

  • 2836 - 2841

Electronic International Standard Serial Number (EISSN)

  • 1365-2966

International Standard Serial Number (ISSN)

  • 0035-8711

Digital Object Identifier (DOI)

  • 10.1093/mnras/stu1956

Citation Source

  • Scopus