Joint NuSTAR and Chandra analysis of the obscured quasar in IC 2497 - Hanny's Voorwerp system

Abstract

We present new Nuclear Spectroscopic Telescope Array (NuSTAR) observations of the core of IC 2497, the galaxy associated with Hanny's Voorwerp. The combined fits of the Chandra (0.5-8 keV) and NuSTAR (3-24 keV) X-ray spectra, together with WISE mid-IR photometry, optical longslit spectroscopy and optical narrow-band imaging, suggest that the galaxy hosts a Compton-thick AGN ($N_{\mathrm{H}}\sim 2\times 10^{24}$ cm${}^{-2}$, current intrinsic luminosity $L_{\mathrm{bol}}\sim 2-5\times 10^{44}$ erg s${}^{-1}$) whose luminosity dropped by a factor of $\sim$50 within the last $\sim 100$ kyr. This corresponds to a change in Eddington ratio from ${\lambda }_{\mathrm{Edd}}\sim$ 0.35 to ${\lambda }_{\mathrm{Edd}}\sim$ 0.007. We argue that the AGN in IC 2497 should not be classified as a changing-look AGN, but rather we favour the interpretation where the AGN is undergoing a change in accretion state (from radiatively efficient to radiatively inefficient). In this scenario the observed drop in luminosity and Eddington ratio corresponds to the final stage of an AGN accretion phase. Our results are consistent with previous studies in the optical, X-ray and radio although the magnitude of the drop is lower than previously suggested. In addition, we discuss a possible analogy between X-ray binaries and an AGN.

9 pages, 3 figures. Accepted for publication in MNRAS

References in corpus (14)

• Modelling the behaviour of accretion flows in X-ray binaries
• The Illustris simulation: the evolving population of black holes across cosmic time
• The Discovery of the First "Changing Look" Quasar: New Insights into the Physics & Phenomenology of AGN
• On the X-ray, optical emission line and black hole mass properties of local Seyfert galaxies
• Radiatively Inefficient Accretion in Nearby Galaxies
• NuSTAR Observations of the Bullet Cluster: Constraints on Inverse Compton Emission
• AGN Type-casting: Mrk 590 No Longer Fits the Role
• Fuelling Active Galactic Nuclei
• iPTF Discovery of the Rapid "Turn On" of a Luminous Quasar
• The Close AGN Reference Survey (CARS) - Mrk 1018 returns to the shadows after 30 years as a Seyfert 1
• Iron K$\alpha$ emission in type-I and type-II Active Galactic Nuclei
• Fading AGN Candidates: AGN Histories and Outflow Signatures
• The Sudden Death of the Nearest Quasar
• The Close AGN Reference Survey (CARS) - What is causing Mrk1018's return to the shadows after 30 years?

Cited by in corpus (10)

• The last migration trap of compact objects in AGN accretion disc
• Detecting and Characterizing Young Quasars II: Four Quasars at $z\sim 6$ with Lifetimes $<10^4$ years
• Fading AGN in Post-Starburst Galaxies
• NuSTAR Observations of AGN with Low Observed X-ray to [OIII] Luminosity Ratios: Heavily Obscured AGN or Turned-Off AGN?
• Galaxy and Mass Assembly (GAMA): A $\text{WISE}$ study of the activity of emission-line systems in G23
• Jet-ISM interaction in NGC 1167 / B2 0258+35, A LINER with an AGN past
• Relic jet activity in "Hanny's Voorwerp" revealed by the LOFAR Two metre Sky Survey
• The interaction of the active nucleus with the host galaxy interstellar medium
• eROSITA Final Equatorial-Depth Survey (eFEDS): eFEDS X-ray view of WERGS Radio Galaxies selected by the Subaru/HSC and VLA/FIRST survey
• A candidate Optically Quiescent Quasar lacking narrow emission lines