Large-scale distribution of galaxies at the Galactic poles

Abstract

GALAXIES, mapped in two or three dimensions, are not distributed randomly but are clustered on small scales (<5 h⁻¹ Mpc, where h ≈ 0.5–1 is Hubble's constant in units of 100 km s⁻¹Mpc⁻¹), for reasons conventionally ascribed to the effects of gravity. Whether galaxies remain correlated on very large scales (∼ 50–100 h⁻¹ Mpc) is of particular interest, because such structures are unexpected in most cosmological theories. We have combined data from four distinct surveys at the north and south Galactic poles to produce a well sampled distribution of galaxies by redshift on a linear scale extending to 2,000h⁻¹ Mpc. Here we report our finding of an excess correlation and an apparent regularity in the galaxy distribution with a characteristic scale of 128 h⁻¹ Mpc. This structure is revealed only after the completion of recent surveys extending to redshift z > 0.2. Similarly deep surveys with greater angular spread are needed to verify our results and to determine the implications for cosmology.