The "Green Bean" Galaxy SDSS J224024.1--092748: Unravelling the emission signature of a quasar ionization echo

Abstract

"Green Bean" Galaxies (GBs) are the most [O III]-luminous type-2 active galactic nuclei (AGN) at z~0.3. However, their infrared luminosities reveal AGN in very low activity states, indicating that their gas reservoirs must be ionized by photons from a recent high activity episode - we are observing quasar ionization echoes. We use integral field spectroscopy from the Gemini Multi-Object Spectrograph to analyse the 3D kinematics, ionization state, temperature and density of ionized gas in the GB SDSS J224024.1-092748. We model the emission line spectrum of each spaxel as a superposition of up to three Gaussian components and analyse the physical properties of each component individually. Two narrow components, tracing the velocity fields of the disc and an ionized gas cloud, are superimposed over the majority of the galaxy. Fast shocks produce hot ($T_e$ $\ge$ 20,000 K), dense ($n_e$ $\ge$ 100 cm${}^{-3}$), turbulent ($\sigma$ $\ge$ 600 km s${}^{-1}$), [O III]-bright regions with enhanced [N II]/H$\alpha$ and [S II]/H$\alpha$ ratios. The most prominent such spot is consistent with a radio jet shock-heating the interstellar medium. However, the AGN is still responsible for $\ge$ 82 per cent of the galaxy's total [O III] luminosity, strengthening the case for previous quasar activity. The ionized gas cloud has a strong kinematic link to the central AGN and is co-rotating with the main body of the galaxy, suggesting that it may be the remnant of a quasar-driven outflow. Our analysis of J224024.1-092748 indicates that GBs provide a unique fossil record of the transformation from the most luminous quasars to weak AGN.

24 pages, 15 figures, accepted for publication in MNRAS; affiliations and acknowledgements updated

References in corpus (11)

• The MAPPINGS III Library of Fast Radiative Shock Models
• Mayavi: a package for 3D visualization of scientific data
• Resolving the electron temperature discrepancies in HII Regions and Planetary Nebulae: kappa-distributed electrons
• The SAMI Galaxy Survey: Shocks and Outflows in a normal star-forming galaxy
• Quasars Are Not Light-Bulbs: Testing Models of Quasar Lifetimes with the Observed Eddington Ratio Distribution
• Extended Emission-Line Regions: Remnants of Quasar Superwinds?
• Neon and Argon optical emission lines in ionized gaseous nebulae: Implications and applications
• The Sudden Death of the Nearest Quasar
• Gemini Long-slit Observations of Luminous Obscured Quasars: Further Evidence for an Upper Limit on the Size of the Narrow-Line Region
• A sample of Seyfert-2 galaxies with ultra-luminous galaxy-wide NLRs -- Quasar light echos?
• Empirical Corrections for Charge Transfer Inefficiency and Associated Centroid Shifts for STIS CCD Observations

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• NuSTAR Observations of AGN with Low Observed X-ray to [OIII] Luminosity Ratios: Heavily Obscured AGN or Turned-Off AGN?
• NuSTAR hard X-ray data and Gemini 3D spectra reveal powerful AGN and outflow histories in two low-redshift Lyman-$\alpha$ blobs
• Gemini Multi-Object Spectrograph Integral Field Unit Spectroscopy of the Double-peaked Broad Emission Line of a Red Active Galactic Nucleus
• An interacting galaxy pair at the origin of a light echo
• Understanding Lyman-alpha Nebulae at Low Redshift I: The Sizes, Powering, and Kinematics of "Green Bean" Galaxies
• QSO MUSEUM III: the circumgalactic medium in Ly$\alpha$ emission around 120 $z\sim 3$ quasars covering the SDSS parameter space. Witnessing the instantaneous AGN feedback on halo scales
• Powerful yet lonely: Is 3C 297 a high-redshift fossil group?