Testing the Origin of the CMB Large-Angle Correlation Deficit with a Galaxy Imaging Survey

TL;DR

This paper investigates whether large-scale structure surveys can test the hypothesis that primordial power suppression explains the CMB large-angle correlation deficit, finding that imaging surveys are promising but limited in conclusively ruling out this explanation.

Contribution

It compares the effectiveness of photometric and spectroscopic surveys in constraining primordial power suppression related to CMB anomalies.

Findings

Spectroscopic surveys have more radial modes but are less advantageous than photometric surveys.

Photometric redshift calibration precision has little impact on constraining power.

Wide-area imaging surveys can test models but may not definitively confirm or refute primordial power suppression.

Abstract

The cosmic microwave background (CMB) temperature distribution measured by the Wilkinson Microwave Anisotropy Probe (WMAP) exhibits anomalously low correlation at large angles. Quantifying the degree to which this feature in the temperature data is in conflict with standard Lambda-CDM cosmology is somewhat ambiguous because of the a posteriori nature of the observation. One physical mechanism that has been proposed as a possible explanation for the deficit in the large-angle temperature correlations is a suppression of primordial power on ~Gpc scales. To distinguish whether the anomaly is a signal of new physics, such as suppressed primordial power, it would be invaluable to perform experimental tests of the authenticity of this signal in data sets which are independent of the WMAP temperature measurements or even other CMB measurements. We explore the possibility of testing models of power suppression with large-scale structure observations, and compare the ability of planned photometric and spectroscopic surveys to constrain the power spectrum. Of the surveys planned for the next decade, a spectroscopic redshift survey such as BigBOSS will have a greater number of radial modes available for study, but we find that this advantage is outweighed by the greater surface density of high-redshift sources that will be observed by photometric surveys such as LSST or Euclid. We also find that the ability to constrain primordial power suppression is insensitive to the precision of the calibration of photometric redshifts. We conclude that very-wide-area imaging surveys have the potential to probe viable models for the missing power but that it will be difficult to use such surveys to conclusively rule out primordial power suppression as the mechanism behind the observed anomaly.