MAD Adaptive Optics Imaging of High Luminosity Quasars: A Pilot Project

TL;DR

This pilot project demonstrates the potential of adaptive optics imaging with the VLT to resolve host galaxies of high-luminosity quasars at high redshift, despite suboptimal observing conditions.

Contribution

It showcases the capabilities of multi-conjugated adaptive optics for high-resolution imaging of distant quasars and their host galaxies, including simulations for future extremely large telescopes.

Findings

Achieved ~0.2 arcsec resolution under poor seeing conditions.

Characterized host galaxy properties for 2 quasars at z~2.

Set upper limits on host galaxy luminosities for others.

Abstract

We present near-IR images of five luminous quasars at z~2 and one at z~4 obtained with an experimental adaptive optics instrument at the ESO Very Large Telescope. The observations are part of a program aimed at demonstrating the capabilities of multi-conjugated adaptive optics imaging combined with the use of natural guide stars for high spatial resolution studies on large telescopes. The observations were mostly obtained under poor seeing conditions but in two cases. In spite of these non optimal conditions, the resulting images of point sources have cores of FWHM ~0.2 arcsec. We are able to characterize the host galaxy properties for 2 sources and set stringent upper limits to the galaxy luminosity for the others. We also report on the expected capabilities for investigating the host galaxies of distant quasars with adaptive optics systems coupled with future Extremely Large Telescopes. Detailed simulations show that it will be possible to characterize compact (2-3 kpc) quasar host galaxies for QSOs at z = 2 with nucleus K-magnitude spanning from 15 to 20 (corresponding to absolute magnitude -31 to -26) and host galaxies that are 4 mag fainter than their nuclei.