Now You See It, Now You Don't: The Disappearing Central Engine of the Quasar J1011+5442

By J. Runnoe, S. Cales, J. Ruan, M. Eracleous, S. Anderson, Yue Shen, P. Green, E. Morganson, S. LaMassa, Jenny E. Greene and 12 more. 2015

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We report the discovery of a new "changing-look" quasar, SDSS J101152.98+544206.4, through repeat spectroscopy from the Time Domain Spectroscopic Survey. This is an addition to a small but growing set of quasars whose blue continua and broad optical emission lines have been observed to decline by a large factor on a time scale of approximately a decade. The 5100 Angstrom monochromatic continuum luminosity of this quasar drops by a factor of > 9.8 in a rest-frame time interval of < 9.7 years, while the broad H-alpha luminosity drops by a factor of 55 in the same amount of time. The width of the broad H-alpha line increases in the dim state such that the black hole mass derived from the appropriate single-epoch scaling relation agrees between the two epochs within a factor of 3. The fluxes of the narrow emission lines do not appear to change between epochs. The light curve obtained by the Catalina Sky Survey suggests that the transition occurs within a rest-frame time interval of approximately 500 days. We examine three possible mechanisms for this transition suggested in the recent literature. An abrupt change in the reddening towards the central engine is disfavored by the substantial difference between the timescale to obscure the central engine and the observed timescale of the transition. A decaying tidal disruption flare is consistent with the decay rate of the light curve but not with the prolonged bright state preceding the decay, nor can this scenario provide the power required by the luminosities of the emission lines. An abrupt drop in the accretion rate onto the supermassive black hole appears to be the most plausible explanation for the rapid dimming.

View Paper: https://www.semanticscholar.org/paper/09536c98c39f8e1d0db3dea4b6fceac253abfd44

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Citations in the corpus

• New Physical Insights about Tidal Disruption Events from a Comprehensive Observational Inventory at X-Ray Wavelengths (2016, background): “Even though Runnoe et al. (2016) attribute the changes in the spectrum to changes in the accretion rate onto the BH, they also suggest that a TDE scenario could be responsible for the changes in the observed optical spectrum.”
• Raining on black holes and massive galaxies: the top-down multiphase condensation model (2016, background): “The true is valid in the opposite direction, i.e. the AGN can dim by over 1 dex, as the cold clouds are consumed, thus explaining the recently discovered changing-look quasars (Runnoe et al. 2016).”
• A systematic search for changing-look quasars in SDSS (2015, background): “SEQUELS_TARGET and TDSS_FES_NQHISN target in BOSS.”