Lensing as a Probe of Early Universe: from CMB to Galaxies

TL;DR

This paper explores how CMB lensing and galaxy lensing can detect deviations from isotropy and scale invariance in the primordial power spectrum, providing insights into early universe physics.

Contribution

It demonstrates the potential of CMB and galaxy lensing cross-correlations to probe primordial power spectrum features and anisotropies, including dipole asymmetry and local features.

Findings

CMB lensing and galaxy lensing can detect scale-dependent dipole asymmetry.

Cross-correlation methods can probe local features on smaller scales.

Current data constrains amplitude and scale dependence of dipole asymmetry.

Abstract

The Cosmic Microwave Background (CMB) radiation lensing is a promising tool to study the physics of early universe. In this work we probe the imprints of deviations from isotropy and scale invariance of primordial curvature perturbation power spectrum on CMB lensing potential and convergence. Specifically, we consider a scale-dependent hemispherical asymmetry in primordial power spectrum. We show that the CMB lensing potential and convergence and also the cross-correlation of the CMB lensing and late time galaxy convergence can probe the amplitude and the scale dependence of the dipole modulation. As another example, we consider a primordial power spectrum with local feature. We show that the CMB lensing and the cross-correlation of the CMB lensing and galaxy lensing can probe the amplitude and the shape of the local feature. We show that the cross correlation of CMB lensing convergence and galaxy lensing is capable to probe the effects of local features in power spectrum on smaller scales than the CMB lensing. Finally we showed that the current data can constrain the amplitude and moment dependence of dipole asymmetry.