Opening the Era of Quasar-host Studies at High Redshift with JWST

Abstract We measure the host galaxy properties of five quasars with z ∼ 1.6–3.5 selected from the Sloan Digital Sky Survey (SDSS) and AEGIS, which fall within the JWST/Hubble Space Telescope (HST) CEERS survey area. A point-spread function library is constructed based on stars in the full field of view of the data and used with the 2D image modeling tool galight to decompose the quasar and its host with multiband 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 ∼ 2 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 active galactic nucleus feedback models.