Density mapping with weak lensing and phase information

TL;DR

This paper introduces a novel method combining weak lensing and galaxy positions to reconstruct the universe's density field, effectively calibrating bias and achieving high-resolution results beyond traditional limits.

Contribution

It proposes a maximum-probability reconstruction method using phase information from galaxy positions and shear data, improving density mapping accuracy.

Findings

Effective reconstruction down to scales beyond l=1000

Phase-based prior reduces bias impact

Method outperforms traditional lensing-only reconstructions

Abstract

The available probes of the large scale structure in the Universe have distinct properties: galaxies are a high resolution but biased tracer of mass, while weak lensing avoids such biases but, due to low signal-to-noise ratio, has poor resolution. We investigate reconstructing the projected density field using the complementarity of weak lensing and galaxy positions. We propose a maximum-probability reconstruction of the 2D lensing convergence with a likelihood term for shear data and a prior on the Fourier phases constructed from the galaxy positions. By considering only the phases of the galaxy field, we evade the unknown value of the bias and allow it to be calibrated by lensing on a mode-by-mode basis. By applying this method to a realistic simulated galaxy shear catalogue, we find that a weak prior on phases provides a good quality reconstruction down to scales beyond l=1000, far into the noise domain of the lensing signal alone.