Large-Scale Structure and Future Surveys

TL;DR

The paper argues that the most informative next step in large-scale structure studies is to access the linear regime at higher redshift, notably around $z=3$. It proposes a large spectroscopic survey of roughly half a million Lyman-break galaxies over ~150 deg$^{2}$ to map the linear power spectrum to $k\lesssim0.5 h$ Mpc$^{-1}$ and detect multiple baryon acoustic oscillations, providing measurements of the angular diameter distance and $H(z)$ at $z=3$ that complement CMB and supernova probes. The author compares survey volumes across current and planned programs, advocates spectroscopy over imaging due to better line-of-sight information and control of systematics, and outlines the feasibility and scientific payoff of such a survey as a clear path forward for cosmology. Overall, the work highlights a high-redshift, BAO-driven approach as a powerful means to sharpen constraints on cosmological parameters and the nature of dark energy and gravity.

Abstract

As the 2dF Galaxy Redshift Survey and Sloan Digital Sky Survey move toward completion, it is time to ask what the next generation of survey of large-scale structure should be. I discuss some of the cosmological justifications for such surveys and conclude that surveys at z=3 offer a critical advantage in their ability to access linear-regime clustering at scales smaller than any current survey and even the CMB. I discuss a possible implementation of such a survey and highlight some of the potential science return.

Figures (1)

• Figure 1: The statistical error bars on a large redshift survey at $z=3$ superposed on the power spectra of two different cosmological models. The power spectra have been divided by the zero-baryon power spectra of their $\Omega_m$ and $H_0$. Both cosmological models have the usual baryon density of Big Bang nucleosynthesis. The top curve has $\Omega_m=0.35$ and $H_0=70$ km/s/Mpc, while the bottom curve has $\Omega_m=0.25$ and $H_0=65$ km/s/Mpc. The baryon acoustic oscillations are the wiggles in both power spectra. We have assumed 600,000 galaxies spread over $0.6{h^{-3}\rm\,Gpc^3}$. The galaxies are assumed to have a clustering amplitude of $\sigma_8=1$. The survey would detect 3 or 4 of the acoustic oscillations, depending on cosmology, with a marginal detection of one additional peak. The arrows show the range of the linear regime at different redshifts and for two CMB experiments, MAP and Planck.