Near-infrared adaptive optics imaging of high redshift quasars

TL;DR

This study uses adaptive optics near-infrared imaging to analyze high redshift quasar host galaxies, revealing their properties and evolutionary trends consistent with massive ellipticals, and showing they are already mature at early cosmic times.

Contribution

First near-infrared adaptive optics imaging of high redshift quasar hosts, demonstrating their properties and passive evolution consistent with massive elliptical galaxies.

Findings

Host galaxies are consistent with massive ellipticals (~-24.7 to -23.8 mag).

Radio loud quasar hosts follow passive evolution similar to radio galaxies.

Quasar host galaxies are already fully formed at ~2 Gyr after the Big Bang.

Abstract

The properties of high redshift quasar host galaxies are studied, in order to investigate the connection between galaxy evolution, nuclear activity, and the formation of supermassive black holes. We combine new near-infrared observations of three high redshift quasars (2 < z < 3), obtained at the ESO Very Large Telescope equipped with adaptive optics, with selected data from the literature. For the three new objects we were able to detect and characterize the properties of the host galaxy, found to be consistent with those of massive elliptical galaxies of M(R) ~ -24.7 for the one radio loud quasar, and M(R) ~ -23.8 for the two radio quiet quasars. When combined with existing data at lower redshift, these new observations depict a scenario where the host galaxies of radio loud quasars are seen to follow the expected trend of luminous (~5L*) elliptical galaxies undergoing passive evolution. This trend is remarkably similar to that followed by radio galaxies at z > 1.5. Radio quiet quasars hosts also follow a similar trend but at a lower average luminosity (~0.5 mag dimmer). The data indicate that quasar host galaxies are already fully formed at epochs as early as ~2 Gyr after the Big Bang and then passively fade in luminosity to the present epoch.