Magnification as a Probe of Dark Matter Halos at high redshift

TL;DR

This paper introduces a novel lensing magnification method to measure dark matter halo profiles at high redshift using photometric redshifts, avoiding the need for galaxy shape measurements.

Contribution

It presents a new approach leveraging lensing magnification with photometric redshifts to study dark matter halos at high redshift, demonstrated through a feasibility study.

Findings

Magnification can probe dark matter halos without galaxy shape data.

Stacking of high-redshift galaxies enhances signal detection.

New observational window for high-redshift dark matter studies.

Abstract

We propose a new approach for measuring the mass profile and shape of groups and clusters of galaxies, which uses lensing magnification of distant background galaxies. The main advantage of lensing magnification is that, unlike lensing shear, it relies on accurate photometric redshifts only and not galaxy shapes, thus enabling the study of the dark matter distribution with unresolved source galaxies. We present a feasibility study, using a real population of z > 2.5 Lyman Break Galaxies as source galaxies, and where, similar to galaxy-galaxy lensing, foreground lenses are stacked in order to increase the signal-to-noise. We find that there is an interesting new observational window for gravitational lensing as a probe of dark matter halos at high redshift, which does not require measurement of galaxy shapes.