The Local Perspective on the Hubble Tension: Local Structure Does Not Impact Measurement of the Hubble Constant

W. D'Arcy Kenworthy, Dan Scolnic, Adam Riess

Published 2019-01-24Version 1

We use the largest sample to date of spectroscopic SN Ia distances and redshifts to look for evidence in the Hubble diagram of large scale outflows caused by local voids suggested to exist at z<0.15 . Our sample combines data from the Pantheon sample with the Foundation survey and the most recent release of lightcurves from the Carnegie Supernova Project to create a sample of 1295 SNe over a redshift range of 0.01<z<2.26. We make use of an inhomogeneous and isotropic Lemaitre-Tolman-Bondi metric to model a void in the SN Ia distance-redshift relation. We conclude that the SN luminosity distance-redshift relation is inconsistent at the 4-5 sigma confidence level with large local underdensities (|delta| > 20%, where the density contrast delta = Delta-rho / rho) proposed in some galaxy count studies, and find no evidence of a change in the Hubble constant corresponding to a void with a sharp edge in the redshift range 0.023<z<0.15. We conclude that the distance-ladder value of H_0, with a current precision of sigma H_0=2.2%, is not significantly affected by local density contrasts, with an empirical precision of sigma H_0 ~ 0.60%, in agreement with cosmic variance in the Hubble constant of sigma H_0 = 0.42% predicted from simulations of large-scale structure. We derive a 5 sigma constraint on local density contrasts on scales larger than 69 Mpc h^-1 of |delta| < 27%. The presence of local structure does not appear to impede the possibility of measuring the Hubble constant to 1% precision.