Cross-Correlation study between CMB lensing and galaxy surveys

TL;DR

This study investigates the cross-correlation between CMB lensing and galaxy surveys to constrain cosmological parameters and test the $\\Lambda$CDM model using simulated data and maximum likelihood analysis.

Contribution

It introduces a method to analyze cross-correlations between CMB lensing and galaxy density fields for parameter estimation and model validation.

Findings

Successfully constrained galaxy bias and amplitude scaling parameters.

Validated the approach using simulations mimicking Herschel HELP data.

Provided a framework for combining CMB and galaxy survey data for cosmological studies.

Abstract

Cosmic Microwave Background (CMB) is a powerful probe to study the early universe and various cosmological models. Weak gravitational lensing affects the CMB by changing its power spectrum, but meanwhile, it also carries information about the distribution of lensing mass and hence, the large scale structure (LSS) of the universe. When studies of the CMB is combined with the tracers of LSS, one can constrain cosmological models, models of LSS development and astrophysical parameters simultaneously. The main focus of this project is to study the cross-correlations between CMB lensing and the galaxy matter density to constrain the galaxy bias ($b$) and the amplitude scaling parameter ($A$), to test the validity of $\Lambda$CDM model. We test our approach for simulations of the Planck CMB convergence field and galaxy density field, which mimics the density field of the Herschel Extragalactic Legacy Project (HELP). We use maximum likelihood method to constrain the parameters.