alexa The Supernova Cosmology ProjectMeasurements of Ω and Λ from 42 high-redshift supernovae.


International Journal of Advance Innovations, Thoughts & Ideas

Author(s): Perlmutter S, Aldering G, Goldhaber G, Knop RA, Nugent P

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We report measurements of the mass density, and cosmological-constant energy density, of ) M , ) " , the universe based on the analysis of 42 type Ia supernovae discovered by the Supernova Cosmology Project. The magnitude-redshift data for these supernovae, at redshifts between 0.18 and 0.83, are –tted jointly with a set of supernovae from the Supernova Survey, at redshifts below 0.1, to yield Cala ç n/Tololo values for the cosmological parameters. All supernova peak magnitudes are standardized using a SN Ia light-curve width-luminosity relation. The measurement yields a joint probability distribution of the cosmological parameters that is approximated by the relation in the region 0.8 ) M [ 0.6 ) " B [ 0.2 ^ 0.1 of interest For a —at cosmology we –nd (1 p statistical) ( ) M [ 1.5). ( ) M ] ) " \ 1) ) M flat \ 0.28 ~0.08 ` 0.09 ~0.04 ` 0.05 (identi–ed systematics). The data are strongly inconsistent with a " \ 0 —at cosmology, the simplest in—ationary universe model. An open, " \ 0 cosmology also does not –t the data well : the data indicate that the cosmological constant is nonzero and positive, with a con–dence of P ( "[ 0) \ 99%, including the identi–ed systematic uncertainties. The best-–t age of the universe relative to the Hubble time is Gyr for a —at cosmology. The size of our sample allows us to perform a variety of t 0 flat \ 14.9 ~1.1 ` 1.4 (0.63/ h ) statistical tests to check for possible systematic errors and biases. We –nd no signi–cant diÜerences in either the host reddening distribution or Malmquist bias between the low-redshift sample Cala ç n/Tololo and our high-redshift sample. Excluding those few supernovae that are outliers in color excess or –t residual does not signi–cantly change the results. The conclusions are also robust whether or not a width-luminosity relation is used to standardize the supernova peak magnitudes. We discuss and con- strain, where possible, hypothetical alternatives to a cosmological constant. Subject headings : cosmology : observations » distance scale » supernovae : general

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This article was published in The Astrophysical Journal and referenced in International Journal of Advance Innovations, Thoughts & Ideas

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