Using strong gravitational lensing to zoom in on high-redshift galaxies

TL;DR

This paper discusses how combining strong gravitational lensing with VLBI observations enables detailed study of high-redshift galaxies' mass distribution and structures, overcoming observational challenges at large cosmic distances.

Contribution

It highlights the potential of wide-field VLBI surveys to discover more radio-loud lensed systems, enhancing high-redshift galaxy research.

Findings

Potential to unveil complex mass distributions in lensing galaxies

Ability to detect faint cold molecular gas reservoirs at high redshift

Prospects for identifying offset and binary AGN candidates at z>1

Abstract

The centres of galaxies are powerful laboratories to test the current $\Lambda$CDM model for structure formation and evolution. While these sub-galactic scales can be directly investigated in the local Universe, it is observationally extremely difficult to access them at high redshift. The combination of strong gravitational lensing and VLBI observations allows us to access these scales to study both the baryonic and the dark matter distribution at the largest distances. For example, it becomes possible to unveil complex mass density distribution of lensing galaxies, faint cold molecular gas reservoirs, offset and binary AGN candidates at $z>1$. Currently, these detailed studies are limited by the small number of known radio-loud lensed sources. Wide-field VLBI observations may provide a viable way to search for many more radio-loud systems and test strategies in preparation for the future surveys with the next generation of interferometers.