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Date and Time of the Query: 2019-04-25 T19:34:55 PDT
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For refcode 2002MNRAS.332..352R:
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Copyright by Royal Astronomical Society. 2002MNRAS.332..352R Do Type Ia supernovae prove {LAMBDA} > 0? Michael Rowan-Robinson ABSTRACT The evidence for positive cosmological constant {LAMBDA} from Type Ia supernovae is re-examined. Both high redshift supernova teams are found to underestimate the effects of host galaxy extinction. The evidence for an absolute magnitude-decay time relation is much weakened if supernovae not observed before maximum light are excluded. Inclusion of such objects artificially suppresses the scatter about the mean relation. With a consistent treatment of host galaxy extinction and elimination of supernovae not observed before maximum, the evidence for a positive lambda is not very significant (3-4 {sigma}). A factor which may contribute to apparent faintness of high-z supernovae is evolution of the host galaxy extinction with z. The Hubble diagram using all high-z distance estimates, including SZ clusters and gravitational lens time-delay estimates, does not appear inconsistent with an {OMEGA}_0_ = 1 model. Although a positive {LAMBDA} can provide an (albeit physically unmotivated) resolution of the low curvature implied by cosmic microwave background (CMB) experiments and evidence that {OMEGA}_0_ < 1 from large-scale structure, the direct evidence from Type Ia supernovae seems at present to be inconclusive. Keywords: supernovae: general - cosmological parameters - cosmology: observations.
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