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 of the extragalactic distance ladder. Yet, the galaxy's distance modulus has long been an issue of contention, in particular in view of claims that most newly determined distance moduli cluster tightly-and with a small spread-around the "canonical" distance modulus, (m − M) 0 = 18.50 mag. We compiled 233 separate LMC distance determinations published between 1990 and 2013. Our analysis of the individual distance moduli, as well as of their two-year means and standard deviations resulting from this largest data set of LMC distance moduli available to date, focuses specifically on Cepheid and RR Lyrae variable-star tracer populations, as well as on distance estimates based on features in the observational Hertzsprung-Russell diagram. We conclude that strong publication bias is unlikely to have been the main driver of the majority of published LMC distance moduli. However, for a given distance tracer, the body of publications leading to the tightly clustered distances is based on highly non-independent tracer samples and analysis methods, hence leading to significant correlations among the LMC distances reported in subsequent articles. Based on a careful, weighted combination, in a statistical sense, of the main stellar population tracers, we recommend that a slightly adjusted canonical distance modulus of (m − M) 0 = 18.49 ± 0.09 mag be used for all practical purposes that require a general distance scale without the need for accuracies of better than a few percent.

The VMC Survey. XXII. Hierarchical Star Formation in the 30 Doradus-N158–N159–N160 Star-forming Complex

“…1, we overplot PAR-SEC isochrones (version 1.2S; Bressan et al 2012) of metallicity Z = 0.008 and ages log(τ /yr) = 6.6, 7.0, 7.5, 8.0, and 9.0, shifted by an LMC distance modulus of (m − M ) 0 = 18.49 mag (Pietrzyński et al 2013;de Grijs et al 2014) and assuming zero extinction. We have subtracted offsets of 0.026 mag in J and 0.003 mag in K s , given by Rubele et al (2015), from the isochrones to correct for the small differences between the VISTA system and the model Vega system.…”

The Properties of the Magellanic Bridge Based on OGLE IV RR Lyrae Variables

“…The variables α and δ are the right ascension and declination of the individual OGLE RR Lyrae stars. This is converted to a physical distance assuming an LMC distance modulus of 18.49 (de Grijs, Wicker & Bono 2014) and an SMC distance modulus of 18.96 (de Grijs & Bono 2015). Figure 3 traces the metallicity changes across the Magellanic system.…”

The VMC survey – XVI. Spatial variation of the cluster formation activity in the innermost regions of the Large Magellanic Cloud

“…We adopted the same distance modulus for all clusters (m − M )0 = 18.49 ± 0.09 mag (de Grijs, Wicker & Bono 2014) and Ks − MK s = (m − M )0 + 0.372E(B − V ), for RV = 3.1 (Cardelli, Clayton & Mathis 1989;Gao et al 2013), since by considering an average depth for the LMC disc of (3.44±1.16) kpc ), we derived a smaller age difference than that resulting from the isochrones (characterized by the same metallicity) bracketing the observed cluster features in the CMD.…”