Opening the era of quasar host studies at high redshift with JWST

TL;DR

This study utilizes JWST to analyze high-redshift quasar host galaxies, revealing their disk-like morphology, compact sizes, and detailed stellar populations, thus advancing understanding of galaxy evolution and AGN host properties at early cosmic times.

Contribution

First demonstration of JWST's capability to detect and spatially resolve quasar hosts at z>3, providing new insights into their structure and stellar populations.

Findings

Quasar hosts are predominantly disk-like without merger signatures.

Hosts are more compact than typical star-forming galaxies at similar mass.

Central regions show higher star formation and younger ages, challenging some AGN feedback models.

Abstract

We measure the host galaxy properties of five quasars with $z\sim 1.6 - 3.5$ selected from SDSS and AEGIS, which fall within the JWST/HST CEERS survey area. A PSF library is constructed based on stars in the full field-of-view of the data and used with the 2-dimensional image modeling tool galight to decompose the quasar and its host with multi-band filters available for HST ACS+WFC3 and JWST NIRCAM (12 filters covering HST F606W to JWST F444W). As demonstrated, JWST provides the first capability to detect quasar hosts at $z>3$ and enables spatially-resolved studies of the underlying stellar populations at $z\sim2$ within morphological structures (spiral arms, bar) not possible with HST. Overall, we find quasar hosts to be disk-like, lack merger signatures, and have sizes generally more compact than typical star-forming galaxies at their respective stellar mass, thus in agreement with results at lower redshifts. The fortuitous face-on orientation of SDSSJ1420+5300A at $z = 1.646$ enables us to find higher star formation and younger ages in the central $2-4$ kpc region relative to the outskirts, which may help explain the relatively compact nature of quasar hosts and pose a challenge to AGN feedback models.