Open AccessDo Type Ia supernovae prove Λ>0?
Author(s) -
RowanRobinson Michael
Publication year - 2002
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1046/j.1365-8711.2002.05299.x
Subject(s) - physics , supernova , astrophysics , galaxy , extinction (optical mineralogy) , cosmic microwave background , redshift , cosmic distance ladder , gravitational lens , hubble's law , type (biology) , astronomy , ecology , quantum mechanics , anisotropy , optics , biology
The evidence for positive cosmological constant Λ 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 σ ) . 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 Ω o =1 model. Although a positive Λ can provide an (albeit physically unmotivated) resolution of the low curvature implied by cosmic microwave background (CMB) experiments and evidence that Ω o <1 from large‐scale structure, the direct evidence from Type Ia supernovae seems at present to be inconclusive.