Gemini Imaging of the Host Galaxies of Changing-Look Quasars

Abstract

Changing-look quasars are a newly-discovered class of luminous active galactic nuclei that undergo rapid ($\lesssim$10 year) transitions between Type 1 and Type 1.9/2, with an associated change in their continuum emission. We characterize the host galaxies of four faded changing-look quasars using broadband optical imaging. We use \textit{gri} images obtained with the Gemini Multi Object Spectrograph (GMOS) on Gemini North to characterize the surface brightness profiles of the quasar hosts and search for [O III] $\lambda 4959,\lambda 5007$ emission from spatially extended regions, or voorwerpjes, with the goal of using them to examine past luminosity history. Although we do not detect, voorwerpjes surrounding the four quasar host galaxies, we take advantage of the dim nuclear emission to characterize the colors and morphologies of the host galaxies. Three of the four galaxies show morphological evidence of merger activity or tidal features in their residuals. The three galaxies which are not highly distorted are fit with a single Sérsic profile to characterize their overall surface brightness profiles. The single-Sérsic fits give intermediate Sérsic indices between the $n=1$ of disk galaxies and the $n=4$ of ellipticals. On a color-magnitude diagram, our changing-look quasar host galaxies reside in the blue cloud, with other AGN host galaxies and star-forming galaxies. On a color-Sérsic index diagram the changing-look quasar hosts reside with other AGN hosts in the "green valley". Our analysis suggests that the hosts of changing-look quasars are predominantly disrupted or merging galaxies that resemble AGN hosts, rather than inactive galaxies.

20 pages, 5 figures

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Cited by in corpus (7)

• The Time Domain Spectroscopic Survey: Changing-Look Quasar Candidates from Multi-Epoch Spectroscopy in SDSS-IV
• A Systematic Analysis of Stellar Populations in the Host Galaxies of Changing-look AGNs
• Local Active Galactic Nuclei with Large Broad-Hα Variability Reside in Red Galaxies
• Host Galaxy Properties of Changing-look AGN Revealed in the MaNGA Survey
• Active galactic nuclei catalog from the AKARI NEP Wide field
• Modeling Star Formation Histories of Changing-Look AGN Host Galaxies with Prospector
• Identifying Changing-Look AGN Transitions in Light Curve Data with the Zwicky Transient Facility