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Galaxy counts and recent measurements of the luminosity density in thenear-infrared (NIR) have indicated the possibility that the local universe maybe under-dense on scales of several hundred megaparsecs. The presence of alarge-scale under-density in the local universe could introduce significantbiases into the interpretation of cosmological observables, and, in particular,into the inferred effects of dark energy on the expansion rate. Here we measurethe K-band luminosity density as a function of redshift to test for such alocal under-density. In this effort, we combine photometry from UKIDSS and2MASS with redshifts from the SDSS, 2DFGRS, 6DFGRS, 2MR, and GAMA surveys. Wefind that the overall shape of the z=0 rest-frame K-band luminosity function(M* = -22.15 +/- 0.04 and alpha = -1.02 +/- 0.03) appears to be relativelyconstant as a function of environment and redshift out to z ~0.2. We find alocal (z < 0.07) luminosity density that is in good agreement with previousstudies. Beyond z ~ 0.07 we detect a rising luminosity density that reaches avalue ~1.5 times higher than that measured locally at z>0.1. This suggests thatthe stellar mass density as a function of redshift follows a similar trend.Assuming that luminous matter traces the underlying dark matter distribution,this implies that the local mass density of the universe may be lower than theglobal value on a scale and amplitude sufficient to introduce significantbiases into the determination of basic cosmological observables, such as theexpansion rate. An under-density of roughly this scale and amplitude would besufficient to resolve the apparent tension between direct measurements of theHubble constant and those inferred by Planck.

Evidence for a ~300 Mpc Scale Under-density in the Local Galaxy Distribution