Gemini Imaging of the Host Galaxies of Changing-look Quasars

Paul J.L. Charlton, John J. Ruan, Daryl Haggard, Scott F. Anderson, Michael Eracleous, Chelsea L. Macleod, Jessie C. Runnoe

Research output: Contribution to journalArticle

Abstract

Changing-look (CL) quasars are a newly discovered class of luminous active galactic nuclei that undergo rapid (≲10 yr) 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 CL quasars using broadband optical imaging. We use gri images obtained with the Gemini Multi-Object Spectrograph on Gemini North to characterize the surface brightness profiles of the quasar hosts and search for [O iii] λ4959, λ5007 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 that 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 CL quasar host galaxies reside in the blue cloud, with other active galactic nucleus (AGN) host galaxies and star-forming galaxies. On a color-Sérsic index diagram the CL quasar hosts reside with other AGN hosts in the "green valley." Our analysis suggests that the hosts of CL quasars are predominantly disrupted or merging galaxies that resemble AGN hosts, rather than inactive galaxies.

Original languageEnglish (US)
Article number75
JournalAstrophysical Journal
Volume876
Issue number1
DOIs
StatePublished - May 1 2019

Fingerprint

quasars
galaxies
active galactic nuclei
diagram
merger
brightness
profiles
color
valley
color-magnitude diagram
disk galaxies
history
spectrographs
valleys
diagrams
luminosity
histories
continuums
broadband
stars

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

Charlton, P. J. L., Ruan, J. J., Haggard, D., Anderson, S. F., Eracleous, M., Macleod, C. L., & Runnoe, J. C. (2019). Gemini Imaging of the Host Galaxies of Changing-look Quasars. Astrophysical Journal, 876(1), [75]. https://doi.org/10.3847/1538-4357/ab0ec1
Charlton, Paul J.L. ; Ruan, John J. ; Haggard, Daryl ; Anderson, Scott F. ; Eracleous, Michael ; Macleod, Chelsea L. ; Runnoe, Jessie C. / Gemini Imaging of the Host Galaxies of Changing-look Quasars. In: Astrophysical Journal. 2019 ; Vol. 876, No. 1.
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abstract = "Changing-look (CL) quasars are a newly discovered class of luminous active galactic nuclei that undergo rapid (≲10 yr) 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 CL quasars using broadband optical imaging. We use gri images obtained with the Gemini Multi-Object Spectrograph on Gemini North to characterize the surface brightness profiles of the quasar hosts and search for [O iii] λ4959, λ5007 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 that are not highly distorted are fit with a single S{\'e}rsic profile to characterize their overall surface brightness profiles. The single-S{\'e}rsic fits give intermediate S{\'e}rsic indices between the n = 1 of disk galaxies and the n = 4 of ellipticals. On a color-magnitude diagram, our CL quasar host galaxies reside in the blue cloud, with other active galactic nucleus (AGN) host galaxies and star-forming galaxies. On a color-S{\'e}rsic index diagram the CL quasar hosts reside with other AGN hosts in the {"}green valley.{"} Our analysis suggests that the hosts of CL quasars are predominantly disrupted or merging galaxies that resemble AGN hosts, rather than inactive galaxies.",
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Charlton, PJL, Ruan, JJ, Haggard, D, Anderson, SF, Eracleous, M, Macleod, CL & Runnoe, JC 2019, 'Gemini Imaging of the Host Galaxies of Changing-look Quasars', Astrophysical Journal, vol. 876, no. 1, 75. https://doi.org/10.3847/1538-4357/ab0ec1

Gemini Imaging of the Host Galaxies of Changing-look Quasars. / Charlton, Paul J.L.; Ruan, John J.; Haggard, Daryl; Anderson, Scott F.; Eracleous, Michael; Macleod, Chelsea L.; Runnoe, Jessie C.

In: Astrophysical Journal, Vol. 876, No. 1, 75, 01.05.2019.

Research output: Contribution to journalArticle

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Charlton PJL, Ruan JJ, Haggard D, Anderson SF, Eracleous M, Macleod CL et al. Gemini Imaging of the Host Galaxies of Changing-look Quasars. Astrophysical Journal. 2019 May 1;876(1). 75. https://doi.org/10.3847/1538-4357/ab0ec1