NASA/IPAC EXTRAGALACTIC DATABASE
Date and Time of the Query: 2018-10-17 T22:58:54 PDT
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For refcode 1996AJ....111....1S:
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Copyright by American Astronomical Society. Reproduced by permission
1996AJ....111....1S BIAS PROPERTIES OF EXTRAGALACTIC DISTANCE INDICATORS. V. H_0_ FROM LUMINOSITY FUNCTIONS OF DIFFERENT SPIRAL TYPES AND LUMINOSITY CLASSES CORRECTED FOR BIAS ALLAN SANDAGE The Observatories of the Carnegie Institution of Washington, 813 Santa Barbara Street, Pasadena, California 91101 Received 1995 July 7; revised 1995 October 12 ABSTRACT The method originally used by Lemaitre (1927, 1931), Robertson (1928), Hubble (1929b), and Hubble & Humason (1931) to determine the Hubble constant at H_0_ ~ 500 km s^-1^ Mpc^-1^ is used again here with modern data. The refinements introduced by van den Bergh (1960a,b) and de Vaucouleurs (1979a,b) of binning the galaxies separately by Hubble type and luminosity class to narrow the dispersions of the individual luminosity functions, are adopted. The mean absolute magnitudes, <M(m,T,L)>, of galaxies of types Sb, Sbc, and Sc in the flux-limited RSA2 catalog varies systematically with luminosity class (L), as van den Bergh had originally demonstrated in his discovery papers. Arguments are given why the absolute magnitudes calculated from redshifts, used here, are more reliable than photometric distances derived in other ways. The local velocity field (v < 4000 km s^-1^) is remarkably quiet when corrected to the Virgocentric frame. Corrections to change the flux-limited luminosity functions to bias-free mean absolute magnitudes for distance-limited samples, <M(o,T,L)>+5 log(H_0_/50), are set out in tables. An absolute calibration of the relative luminosities is made using 11 local galaxies of known distance, giving H_0_ = 56+/-5 km s^-1^ Mpc^-1^. If an analysis had been made that ignored the correction for observational selection bias, an incorrect Hubble constant of 72+/-5 would have been obtained. To make H_0_ ~ 85 as advocated by many proponents of the short distance scale, would require that our present mean absolute magnitude zero point would have to differ from that of the short scale by 0.91 mag, which is a ~5 {sigma}(M) error, showing that the short distance scale is impossible if the distances to the calibrators adopted here are correct.
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