For refcode 1999ApJ...517..565P: Retrieve 104 NED objects in this reference. Please click here for ADS abstract
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1999ApJ...517..565P
Measurements of {OMEGA} and {LAMBDA} from 42 HighRedshift Supernovae
S. PERLMUTTER, G. ALDERING, G. GOLDHABER, R. A. KNOP, P. NUGENT,
P. G. CASTRO, S. DEUSTUA, S. FABBRO, A. GOOBAR, D. E. GROOM,
I. M. HOOK, A. G. KIM, M. Y. KIM, J. C. LEE, N. J. NUNES,
R. PAIN, C. R. PENNYPACKER, AND R. QUIMBY
Institute for Nuclear and Particle Astrophysics, E. O. Lawrence Berkeley
National Laboratory, Berkeley, CA 94720
C. LIDMAN
European Southern Observatory, La Silla, Chile
R. S. ELLIS, M. IRWIN, AND R. G. MCMAHON
Institute of Astronomy, Cambridge, England, UK
P. RUIZLAPUENTE
Department of Astronomy, University of Barcelona, Barcelona, Spain
N. WALTON
Isaac Newton Group, La Palma, Spain
B. SCHAEFER
Department of Astronomy, Yale University, New Haven, CT
B. J. BOYLE
AngloAustralian Observatory, Sydney, Australia
A. V. FILIPPENKO AND T. MATHESON
Department of Astronomy, University of California, Berkeley, CA
A. S. FRUCHTER AND N. PANAGIA
Space Telescope Science Institute, Baltimore, MD
H. J. M. NEWBERG
Fermi National Laboratory, Batavia, IL
AND
W. J. COUCH
University of New South Wales, Sydney, Australia
THE SUPERNOVA COSMOLOGY PROJECT
Received 1998 September 8; accepted 1998 December 17
ABSTRACT
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 supernovae, at
redshifts between 0.18 and 0.83, are fitted jointly with a set of
supernovae from the Calan/Tololo Supernova Survey, at redshifts below 0.1,
to yield values for the cosmological parameters. All supernova 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_^flat^ = 0.28_0.08_^+.09^(1 {sigma}
statistical)_0.04_^+0.05^ (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_^flat^ = 14.9_1.1_^+1.4^(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. Excluding those few supernovae that are outliers in
color excess or fit residual does not significantly change the results. The
conclusions are also robust whether or not a widthluminosity relation is
used to standardize the supernova peak magnitudes. We discuss and
constrain, where possible, hypothetical alternatives to a cosmological
constant.
Subject headings: cosmology: observationsdistance scalesupernovae:
general
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