Evidence for a Nonzero Lambda and a Low Matter Density from a Combined Analysis of the 2dF Galaxy Redshift Survey and Cosmic Microwave Background Anisotropies

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Efstathiou, George; Colless, Matthew; Jackson, Carole; Peterson, Bruce
Description
We perform a joint likelihood analysis of the power spectra of the 2dF Galaxy Redshift Survey (2dFGRS) and the cosmic microwave background (CMB) anisotropies under the assumptions that the initial fluctuations were adiabatic, Gaussian and well described by power laws with scalar and tensor indices of ns and nt. On its own, the 2dFGRS sets tight limits on the parameter combination Ωmh, but relatively weak limits on the fraction of the cosmic matter density in baryons Ωb/Ωm. (Here h is Hubble's...[Show more]
dc.contributor.author  Efstathiou, George  

dc.contributor.author  Colless, Matthew  
dc.contributor.author  Jackson, Carole  
dc.contributor.author  Peterson, Bruce  
dc.date.accessioned  20151213T22:29:12Z  
dc.date.available  20151213T22:29:12Z  
dc.identifier.issn  00358711  
dc.identifier.uri  http://hdl.handle.net/1885/74577  
dc.description.abstract  We perform a joint likelihood analysis of the power spectra of the 2dF Galaxy Redshift Survey (2dFGRS) and the cosmic microwave background (CMB) anisotropies under the assumptions that the initial fluctuations were adiabatic, Gaussian and well described by power laws with scalar and tensor indices of ns and nt. On its own, the 2dFGRS sets tight limits on the parameter combination Ωmh, but relatively weak limits on the fraction of the cosmic matter density in baryons Ωb/Ωm. (Here h is Hubble's constant H0 in units of 100 km s1 Mpc1. The cosmic densities in baryons, cold dark matter and vacuum energy are denoted by Ωb, Ωc and ΩΛ, respectively. The total matter density is Ωm = Ωb + Ωc and the curvature is fixed by Ωk = 1  Ωm  ΩΛ.) The CMB anisotropy data alone set poor constraints on the cosmological constant and Hubble constant because of a 'geometrical degeneracy' among parameters. Furthermore, if tensor modes are allowed, the CMB data allow a wide range of values for the physical densities in baryons and cold dark matter (ωb = Ωbh2 and ωc = Ωch2). Combining the CMB and 2dFGRS data sets helps to break both the geometrical and tensor mode degeneracies. The values of the parameters derived here are consistent with the predictions of the simplest models of inflation, with the baryon density derived from primordial nucleosynthesis and with direct measurements of the Hubble parameter. In particular, we find strong evidence for a positive cosmological constant with a ±2σ range of 0.65 < ΩΛ < 0.85, independently of constraints on ΩΛ derived from Type Ia supernovae.  
dc.publisher  Blackwell Publishing Ltd  
dc.source  Monthly Notices of the Royal Astronomical Society  
dc.subject  Keywords: Cosmic microwave background; Cosmology: Miscellaneous; Galaxies: clusters: general; Largescale structure of universe  
dc.title  Evidence for a Nonzero Lambda and a Low Matter Density from a Combined Analysis of the 2dF Galaxy Redshift Survey and Cosmic Microwave Background Anisotropies  
dc.type  Journal article  
local.description.notes  Imported from ARIES  
local.description.refereed  Yes  
local.identifier.citationvolume  330  
dc.date.issued  2002  
local.identifier.absfor  020110  Stellar Astronomy and Planetary Systems  
local.identifier.ariespublication  MigratedxPub4193  
local.type.status  Published Version  
local.contributor.affiliation  Efstathiou, George, University of Cambridge  
local.contributor.affiliation  Colless, Matthew, College of Physical and Mathematical Sciences, ANU  
local.contributor.affiliation  Jackson, Carole, College of Physical and Mathematical Sciences, ANU  
local.contributor.affiliation  Peterson, Bruce, College of Physical and Mathematical Sciences, ANU  
local.bibliographicCitation.startpage  L29  
local.bibliographicCitation.lastpage  L35  
local.identifier.doi  10.1046/j.13658711.2002.05215.x  
dc.date.updated  20151211T08:47:20Z  
local.identifier.scopusID  2s2.019044369374  
Collections  ANU Research Publications 
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