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Measurements of Omega and Lambda from 42 highredshift supernovae
 Perlmutter, S;
 Aldering, G;
 Goldhaber, G;
 Knop, RA;
 Nugent, P;
 Castro, PG;
 Deustua, S;
 Fabbro, S;
 Goobar, A;
 Groom, DE;
 Hook, IM;
 Kim, AG;
 Kim, MY;
 Lee, JC;
 Nunes, NJ;
 Pain, R;
 Pennypacker, CR;
 Quimby, R;
 Lidman, C;
 Ellis, RS;
 Irwin, M;
 McMahon, RG;
 RuizLapuente, P;
 Walton, N;
 Schaefer, B;
 Boyle, BJ;
 Filippenko, AV;
 Matheson, T;
 Fruchter, AS;
 Panagia, N;
 Newberg, HJM;
 Couch, WJ
 et al.
Published Web Location
https://doi.org/10.1086/307221Abstract
We report measurements of the mass density, Omega_M, and cosmologicalconstant energy density, Omega_Lambda, of the universe based on the analysis of 42 Type Ia supernovae discovered by the Supernova Cosmology Project. The magnituderedshift data for these SNe, at redshifts between 0.18 and 0.83, are fit jointly with a set of SNe from the Calan/Tololo Supernova Survey, at redshifts below 0.1, to yield values for the cosmological parameters. All SN peak magnitudes are standardized using a SN Ia lightcurve widthluminosity relation. The measurement yields a joint probability distribution of the cosmological parameters that is approximated by the relation 0.8 Omega_M  0.6 Omega_Lambda ~= 0.2 +/ 0.1 in the region of interest (Omega_M <~ 1.5). For a flat (Omega_M + Omega_Lambda = 1) cosmology we find Omega_M = 0.28{+0.09,0.08} (1 sigma statistical) {+0.05,0.04} (identified systematics). The data are strongly inconsistent with a Lambda = 0 flat cosmology, the simplest inflationary universe model. An open, Lambda = 0 cosmology also does not fit the data well: the data indicate that the cosmological constant is nonzero and positive, with a confidence of P(Lambda > 0) = 99%, including the identified systematic uncertainties. The bestfit age of the universe relative to the Hubble time is t_0 = 14.9{+1.4,1.1} (0.63/h) Gyr for a flat cosmology. The size of our sample allows us to perform a variety of statistical tests to check for possible systematic errors and biases. We find no significant differences in either the host reddening distribution or Malmquist bias between the lowredshift Calan/Tololo sample and our highredshift sample. The conclusions are robust whether or not a widthluminosity relation is used to standardize the SN peak magnitudes.
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