paper

An Unbiased Estimate of the Global Hubble Constant in the Region of Pisces-Perseus

arXiv:astro-ph/9801256 · doi:10.1086/306009

Abstract

We obtain an unbiased estimate of the global Hubble constant H0 in the volume of cz<12000km/s in the region of Pisces-Perseus. The Tully-Fisher (TF) relation is applied to a magnitude limited sample of 441 spirals selected from the Arecibo 21cm catalog. The photometry data were calibrated with CCD observations and we achieve 0.13mag for the photometric internal error. We use a maximum likelihood method for the TF analysis. Monte-Carlo simulations demonstrate that our method reproduces a given H0 at the 95% confidence level. By applying the method to our sample galaxies, we obtain the unbiased global Hubble constant H0=65+-2(+20,-14) km/s/Mpc; the first and the second terms represent the internal random error and the external errors, respectively. We also find a good agreement for our H0 with those recently obtained via Cepheid observation, the TF relation and supernovae. Hubble velocities of the spirals inferred from our H0 show no significant systematic difference from those given in the Mark III catalog. The same analysis for H0 is carried out using r-band photometry data of the Pisces-Perseus region given by Willick et al.(1997). We obtain a global H0 which is consistent with that obtained from our B-band analysis. A bulk motion in the Pisces-Perseus region is briefly discussed, based on our calibration of H0. Our r-band TF analysis supports the notion of a coherent streaming motion of the Pisces-Perseus ridge with -200km/s with respect to the CMB, in agreement with most modern studies.

40 pages, 27 postscript figures, to appear in Ap.J. Figures are included in the text

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