[Paper Review] Measuring the lensing potential with galaxy clustering

Francesco Montanari, Ruth Durrer|arXiv (Cornell University)|Jun 3, 2015

Galaxies: Formation, Evolution, Phenomena3 citations

TL;DR

This paper proposes measuring the lensing potential using galaxy clustering in future photometric (Euclid-like) and spectroscopic (SKA-like) surveys. Using Fisher matrix forecasts, it demonstrates that the amplitude of the lensing potential can be constrained to a precision comparable to standard LCDM cosmological parameters, offering a robust test of gravity models.

ABSTRACT

We investigate how the lensing potential can be constrained with future galaxy surveys using their number counts. Such a measurement is an independent test of the standard LCDM framework and can be used to discern modified gravity models. We perform a Fisher matrix forecast based on galaxy angular power spectra, assuming specifications consistent with future photometric Euclid-like surveys, for which we provide a computation and fitting formula of magnification bias, and spectroscopic SKA-like surveys. The analysis suggests that the amplitude of the lensing potential can be constrained at the same level as other standard LCDM cosmological parameters.

Motivation & Objective

• To develop a method for constraining the lensing potential using galaxy number counts in future cosmological surveys.
• To test the consistency of the standard LCDM model by measuring the lensing potential independently of other probes.
• To assess the sensitivity of future surveys to detect deviations from general relativity through lensing potential constraints.
• To provide a fitting formula for magnification bias in photometric surveys, improving forecast accuracy.

Proposed method

• Utilizes Fisher matrix forecasts based on galaxy angular power spectra to estimate parameter constraints.
• Incorporates a new computation and fitting formula for magnification bias in photometric surveys, consistent with Euclid-like specifications.
• Applies the same framework to spectroscopic surveys with SKA-like characteristics to assess performance across survey types.
• Assesses the signal-to-noise of the lensing potential amplitude relative to other cosmological parameters in the LCDM framework.

Experimental results

Research questions

• RQ1 Can the lensing potential be measured with sufficient precision using galaxy clustering in future photometric surveys?
• RQ2 How does the constraint on the lensing potential amplitude compare to that of standard LCDM parameters in future surveys?
• RQ3 To what extent can such a measurement distinguish between general relativity and modified gravity models?
• RQ4 What is the impact of accurate magnification bias modeling on the forecast precision of lensing potential constraints?

Key findings

• The amplitude of the lensing potential can be constrained with a precision comparable to other standard LCDM cosmological parameters in future surveys.
• The proposed fitting formula for magnification bias improves the accuracy of forecasts in photometric surveys.
• Both Euclid-like photometric and SKA-like spectroscopic surveys yield competitive constraints on the lensing potential.
• The lensing potential measurement offers a robust, independent test of the LCDM framework and modified gravity scenarios.