Testing the Evolution of the Correlations between Supermassive Black Holes and their Host Galaxies using Eight Strongly Lensed Quasars

TL;DR

This study uses eight strongly lensed quasars observed with Hubble to investigate the relationship between supermassive black hole mass and host galaxy properties at high redshift, leveraging lensing to improve resolution.

Contribution

It demonstrates the feasibility of using strongly lensed AGNs to study black hole-host galaxy correlations at higher redshifts, complementing non-lensed AGN studies.

Findings

Results agree with non-lensed AGN studies, validating the method.

Lensed AGNs can extend the study of black hole-galaxy relations to earlier cosmic times.

Sample size is currently small, serving as a consistency check.

Abstract

One of the main challenges in using high redshift active galactic nuclei to study the correlations between the mass of the supermassive Black Hole (MBH) and the properties of their active host galaxies is instrumental resolution. Strong lensing magnification effectively increases instrumental resolution and thus helps to address this challenge. In this work, we study eight strongly lensed active galactic nuclei (AGN) with deep Hubble Space Telescope imaging, using the lens modelling code Lenstronomy to reconstruct the image of the source. Using the reconstructed brightness of the host galaxy, we infer the host galaxy stellar mass based on stellar population models. MBH are estimated from broad emission lines using standard methods. Our results are in good agreement with recent work based on non-lensed AGN, demonstrating the potential of using strongly lensed AGNs to extend the study of the correlations to higher redshifts. At the moment, the sample size of lensed AGN is small and thus they provide mostly a consistency check on systematic errors related to resolution for the non-lensed AGN. However, the number of known lensed AGN is expected to increase dramatically in the next few years, through dedicated searches in ground and space based wide field surveys, and they may become a key diagnostic of black hole and galaxy co-evolution.