CLUSTERING OF LOCAL GROUP DISTANCES: PUBLICATION BIAS OR CORRELATED MEASUREMENTS? I. THE LARGE MAGELLANIC CLOUD

Abstract

The distance to the Large Magellanic Cloud (LMC) represents a key local rung\nof the extragalactic distance ladder. Yet, the galaxy's distance modulus has\nlong been an issue of contention, in particular in view of claims that most\nnewly determined distance moduli cluster tightly - and with a small spread -\naround the "canonical" distance modulus, (m-M)_0 = 18.50 mag. We compiled 233\nseparate LMC distance determinations published between 1990 and 2013. Our\nanalysis of the individual distance moduli, as well as of their two-year means\nand standard deviations resulting from this largest data set of LMC distance\nmoduli available to date, focuses specifically on Cepheid and RR Lyrae\nvariable-star tracer populations, as well as on distance estimates based on\nfeatures in the observational Hertzsprung-Russell diagram. We conclude that\nstrong publication bias is unlikely to have been the main driver of the\nmajority of published LMC distance moduli. However, for a given distance\ntracer, the body of publications leading to the tightly clustered distances is\nbased on highly non-independent tracer samples and analysis methods, hence\nleading to significant correlations among the LMC distances reported in\nsubsequent articles. Based on a careful, weighted combination, in a statistical\nsense, of the main stellar population tracers, we recommend that a slightly\nadjusted canonical distance modulus of (m-M)_0 = 18.49 +- 0.09 mag be used for\nall practical purposes that require a general distance scale without the need\nfor accuracies of better than a few percent.\n