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Date and Time of the Query: 2019-06-25 T12:42:24 PDT
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For refcode 1988ApJ...331..605S:
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1988ApJ...331..605S THE CASE FOR H_0_ ~ 55 FROM THE 21 CENTIMETER LINEWIDTH ABSOLUTE MAGNITUDE RELATION FOR FIELD GALAXIES ALLAN SANDAGE Center for Astrophysical Sciences in the Department of Physics and Astronomy, The Johns Hopkins University; and Space Telescope Science Institute Received 1987 May 29; accepted 1987 September 9 ABSTRACT It is argued that the high value of the Hubble constant near H_0_ ~ 100 obtained consistently in some programs that use the 21 cm line-width correlation with H band absolute magnitude is too large due to statistical bias in the field galaxy catalogs, insufficiently corrected for. The consequence of the bias is that an apparent increase of H_0_ with distance, ranging between H_0_ ~ 40 locally to H_0_ ~ 100 at about 3 times the Virgo Cluster distance is an artifact caused by use of flux-limited samples. Direct demonstration that the bias is present is made by adding a faint line-width catalog to existing data that are flux-limited at brighter apparent magnitudes, showing a contradiction with the notion of a variable H_0_ outward. The proof is the same as used for ScI galaxies in Paper 1, but here applied to the Tully-Fisher (TF) radio line-width method. Analysis of two line-width catalogs that have different flux limits gives an intrinsic dispersion in absolute magnitude at a given 21 cm line-width of {sigma}(M_B_) ~ 0.9 mag for the H band, and {sigma}(M_B_T__^0,i^) ~ 1.0 mag for the blue band for a distance-limited sample. The TF method is applied to the Kraan-Korteweg and Tammann (KKT) distance-limited 500 km s^-1^ local galaxy sample using data by Huchtmeier and Richter. Calibrating with six local galaxies that have Cepheid distances gives H_0_= 56 +/- 13 km s^-1^ Mpc^-1^. Larger values that reach as high as H_0_ = 68 +/- 18 are obtained from the flux-limited catalogs used here, after attempting to correct them for bias by searching for the apex of the magnitude distribution in the redshift limit of v approaches 0. The conclusion is that incompleteness of the present flux-limited catalogs makes the values obtained in this way uncertain, although they provide upper limits. In the final section it is argued that no presently available distance-limited 21 cm samples exist other than the KKT catalog with which to obtain an unbiased value of H_0_ using the TF method, because the available cluster data appear also to be biased (Teerikorpi; Bottinelli et al.) due to incompleteness. The same conclusion has been reached via a different argument by Kraan-Korteweg, Cameron, and Tammann. Subject headings: cosmology - galaxies: distances - galaxies: internal motions
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