Detection of the Baryon Acoustic Peak in the Large-Scale Correlation Function of SDSS Luminous Red Galaxies

Abstract

We present the large-scale correlation function measured from a
spectroscopic sample of 46,748 luminous red galaxies from the Sloan
Digital Sky Survey. The survey region covers 0.72 h^-3
Gpc³ over 3816 deg² and 0.16<z<0.47, making
it the best sample yet for the study of large-scale structure. We find a
well-detected peak in the correlation function at 100 h^-1 Mpc
separation that is an excellent match to the predicted shape and
location of the imprint of the recombination-epoch acoustic oscillations
on the low-redshift clustering of matter. This detection demonstrates
the linear growth of structure by gravitational instability between
z~1000 and the present and confirms a firm prediction of the standard
cosmological theory. The acoustic peak provides a standard ruler by
which we can measure the ratio of the distances to z=0.35 and z=1089 to
4% fractional accuracy and the absolute distance to z=0.35 to 5%
accuracy. From the overall shape of the correlation function, we measure
the matter density Ω_mh² to 8% and find
agreement with the value from cosmic microwave background (CMB)
anisotropies. Independent of the constraints provided by the CMB
acoustic scale, we find
Ω_m=0.273+/-0.025+0.123(1+w₀)+0.137Ω_K.
Including the CMB acoustic scale, we find that the spatial curvature is
Ω_K=-0.010+/-0.009 if the dark energy is a cosmological
constant. More generally, our results provide a measurement of
cosmological distance, and hence an argument for dark energy, based on a
geometric method with the same simple physics as the microwave
background anisotropies. The standard cosmological model convincingly
passes these new and robust tests of its fundamental properties.

Cite as:
arXiv:astro-ph/0501171v1