A critical review of selected techniques for measuring extragalactic distances

Abstract

An overview is presented of seven of the most reliable indicators used for deriving distances to galaxies as far away as 100 MPC: globular cluster luminosity functions (GCLFs), novae, type-IA supernovae (SN Ia), H I linewidth (Tully-Fisher) relations, planetary-nebular luminosity functions (PNLFs), surface-brightness fluctuations (SBFs), and fundamental-plane relationships for elliptical galaxies (Dn-sigma). The use of Cepheid variables is examined, since these serve to set zero points for most of the methods. Particular attention is paid to the uncertainties inherent in these methods. These uncertainties are tested by comparing distances derived with each technique to distances derived from SBFs. It is found that there are small systematic offsets between the PLNF, GCLF, and SBF methods, with the PNLF and GCLF distances being on average 6 and 13 percent larger than those of the SBF method. A summary of distances to the Virgo cluster is also presented.