Open AccessCosmological parameters from cluster abundances, cosmic microwave background and IRAS
Author(s) -
Bridle S. L.,
Eke V. R.,
Lahav O.,
Lasenby A. N.,
Hobson M. P.,
Cole S.,
Frenk C. S.,
Henry J. P.
Publication year - 1999
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1046/j.1365-8711.1999.02960.x
Subject(s) - physics , cosmic microwave background , astrophysics , hubble's law , cosmology , spectral density , universe , redshift , bispectrum , galaxy , cosmic background radiation , big bang nucleosynthesis , galaxy cluster , age of the universe , cosmological constant , dark matter , sunyaev–zel'dovich effect , structure formation , planck , dark energy , nucleosynthesis , theoretical physics , anisotropy , statistics , stars , quantum mechanics , mathematics
We combine information on cosmological parameters from cluster abundances, CMB primordial anisotropies and the IRAS 1.2‐Jy galaxy redshift survey. We take as free parameters the present values of the total matter density of the universe, Ω m , the Hubble parameter, h , the linear theory rms fluctuations in the matter density within 8 h −1 Mpc spheres, σ 8 , and the IRAS biasing factor, b IRAS . We assume that the universe is spatially flat, with a cosmological constant, and that structure formed from adiabatic initial fluctuations with a Harrison–Zel'dovich power spectrum (i.e. the primordial spectral index n =1 ). The nucleosynthesis value for the baryonic matter density Ω b =0.019/ h 2 is adopted. We use the full three‐ and four‐dimensional likelihood functions for each data set and marginalize these to two‐ and one‐dimensional distributions in a Bayesian way, integrating over the other parameters. It is shown that the three data sets are in excellent agreement, with a best‐fitting point of Ω m =1‐Ω Λ =0.36, h =0.54, σ 8 =0.74, and b IRAS =1.08 . This point is within one sigma of the minimum for each data set alone. Pairs of these data sets have their degeneracies in sufficiently different directions that using only two data sets at a time is sufficient to place good constraints on the cosmological parameters. We show that the results from each of the three possible pairings of the data are also in good agreement. Finally, we combine all three data sets to obtain marginalized 68 per cent confidence intervals of 0.30<Ω m <0.43, 0.48< h <0.59, 0.69< σ 8 <0.79, and 1.01< b IRAS <1.16 . For the best‐fitting parameters the CMB quadrupole is Q rms‐ps =18.0 μK , the shape parameter of the mass power spectrum is Γ=0.15, the baryon density is Ω b =0.066 and the age of the universe is 16.7 Gyr.