Using the Comoving Maximum of the Galaxy Power Spectrum to Measure Cosmological Curvature

TL;DR

This paper uses the comoving maximum in the galaxy power spectrum to measure cosmological curvature, finding consistency with flat universe models and high-redshift galaxy clustering, with implications for structure formation and CMB observations.

Contribution

It introduces a novel method of using the comoving maximum of the galaxy power spectrum as a scale for measuring cosmological curvature and applies it to high-redshift galaxy data.

Findings

The 130 Mpc scale is consistent with a flat universe model.

High-redshift galaxy pairs show a significant excess at ~85-170 Mpc.

The primordial power spectrum spike affects the CMB by amplifying the first Doppler peak.

Abstract

The large-scale maximum at k~0.05 identified in the power-spectrum of galaxy fluctuations provides a co-moving scale for measuring cosmological curvature. In shallow 3D surveys the peak is broad, but appears to be well resolved in 1D, at ~130 Mpc (k=0.048), comprising evenly spaced peaks and troughs. Surprisingly similar behaviour is evident at z=3 in the distribution of Lyman-break galaxies, for which we find a 5 sigma excess of pairs separated by Delta z=0.22pm0.02, equivalent to 85Mpc for Omega=1, increasing to 170 Mpc for Omega=0, with a number density contrast of 30% averaged over 5 independent fields. The combination, 3.2\Omega_m -\Omega_{\Lambda}=0.7, matches the local scale of 130 Mpc, i.e. Omega=0.2\pm0.1 or Omega_{m}=0.4\pm0.1 for the matter-dominated and flat models respectively, with an uncertainty given by the width of the excess correlation. The consistency here of the flat model with SNIa based claims is encouraging, but overshadowed by the high degree of coherence observed in 1D compared with conventional Gaussian models of structure formation. The appearance of this scale at high redshift and its local prominence in the distribution of Abell clusters lends support to claims that the high-z `spikes' represent young clusters. Finally we show that a spike in the primordial power spectrum of delta\rho/\rho=0.3 at k=0.05 has little effect on the CMB, except to exaggerate the first Doppler peak in flat matter-dominated models, consistent with recent observations. \\effect on the CMB, except to exaggerate the first Doppler peak in flat matter-dominated models, consistent with recent observations.