Physics
Scientific paper
Dec 1998
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1998phr...307....1s&link_type=abstract
Physics Reports, Vol. 307, No. 1 - 4, p. 1 - 14
Physics
57
Universe: Age, Universe: Distance Scale, Hubble Constant, Supernovae: Distance Scale
Scientific paper
The status of the HST program to calibrate the absolute magnitude at maximum of non-peculiar Type Ia supernovae is reviewed. Assuming, in first approximation, that SNe Ia are perfect standard candles gives an interim calibration, based on seven SNe Ia in six galaxies for which one has Cepheid distances, of >MB(max)< = -19.52±0.07, >MV(max)< = -19.48±0.07. Applying these calibrations to the Hubble diagram of 52 fiducial SNe Ia with good photometric data, and using a correction of 0.08 mag to an earlier adopted Cepheid period-luminosity relation gives H0 = 55±5 km s-1Mpc-1. Three other methods (via the Virgo cluster distance tied to the global expansion frame, the luminosity function of field spirals calibrated via Cepheids, and the physical methods using gravitational lenses, the Sunyaev-Zel'dovich effect, and expanding SN envelopes) confirm the long distance scale that is implied by this value. Second-parameter corrections to the supernovae method depending on decay rate affect this solution for H0 by, at most, 5%. A critique is given of the "Key Project" result that H0 > 70 (Freedman et al., 1998). Disagreements with their precepts are discussed. The Key Project results, reduced to the Virgo cluster distance of 21.5 Mpc, gives H0 = 55 km s-1Mpc-1. Adopting 13.5 Gyr for the time since the beginning of the expansion gives a timing test value of Ω(total) = 0.44 (-0.37,+1.16). This shows that the timing test for Omega, although powerful in principle because it measures the total mass, is presently impotent because the errors in H0 and Tu are too large. The principal result is that there is no time scale crisis in Big Bang cosmology, sans cosmological constant, because H0-1 > Tu decisively, using the long distance scale derived here.
Saha Avishek
Sandage Alan
Tammann Gustav A.
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