Cosmological parameters degeneracies and non-Gaussian halo bias
- Dipartimento di Astronomia, Università di Bologna, Via Ranzani 1, I-40127 Bologna (Italy)
- Depto. de Física Teórica, IFIC, Universidad de Valencia-CSIC, Edificio de Institutos de Paterna, Apt. 22085, 46071 Valencia (Spain)
- ICREA and Instituto de Ciencias del Cosmos, Universitat de Barcelona, Marti i Franques 1, 08028, Barcelona (Spain)
We study the impact of the cosmological parameters uncertainties on the measurements of primordial non-Gaussianity through the large-scale non-Gaussian halo bias effect. While this is not expected to be an issue for the standard ΛCDM model, it may not be the case for more general models that modify the large-scale shape of the power spectrum. We consider the so-called local non-Gaussianity model, parametrized by the f{sub NL} non-Gaussianity parameter which is zero for a Gaussian case, and make forecasts on f{sub NL} from planned surveys, alone and combined with a Planck CMB prior. In particular, we consider EUCLID- and LSST-like surveys and forecast the correlations among f{sub NL} and the running of the spectral index α{sub s}, the dark energy equation of state w, the effective sound speed of dark energy perturbations c{sup 2}{sub s}, the total mass of massive neutrinos M{sub ν} = Σm{sub ν}, and the number of extra relativistic degrees of freedom N{sub ν}{sup rel}. Neglecting CMB information on f{sub NL} and scales k > 0.03h/Mpc, we find that, if N{sub ν}{sup rel} is assumed to be known, the uncertainty on cosmological parameters increases the error on f{sub NL} by 10 to 30% depending on the survey. Thus the f{sub NL} constraint is remarkable robust to cosmological model uncertainties. On the other hand, if N{sub ν}{sup rel} is simultaneously constrained from the data, the f{sub NL} error increases by ∼ 80%. Finally, future surveys which provide a large sample of galaxies or galaxy clusters over a volume comparable to the Hubble volume can measure primordial non-Gaussianity of the local form with a marginalized 1-σ error of the order Δf{sub NL} ∼ 2−5, after combination with CMB priors for the remaining cosmological parameters. These results are competitive with CMB bispectrum constraints achievable with an ideal CMB experiment.
- OSTI ID:
- 22272789
- Journal Information:
- Journal of Cosmology and Astroparticle Physics, Vol. 2010, Issue 07; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 1475-7516
- Country of Publication:
- United States
- Language:
- English
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