The Man Behind the Curtain: X-rays Drive the UV through NIR Variability in the 2013 AGN Outburst in NGC 2617

B. J. Shappee; J. L. Prieto; D. Grupe; C. S. Kochanek; K. Z. Stanek; G. De Rosa; S. Mathur; Y. Zu; B. M. Peterson; R. W. Pogge; S. Komossa; M. Im; J. Jencson; T. W-S. Holoien; U. Basu; J. F. Beacom; D. M. Szczygiel; J. Brimacombe; S. Adams; A. Campillay; C. Choi; C. Contreras; M. Dietrich; M. Dubberley; M. Elphick; S. Foale; M. Giustini; C. Gonzalez; E. Hawkins; D. A. Howell; E. Y. Hsiao; M. Koss; K. M. Leighly; N. Morrell; D. Mudd; D. Mullins; J. M. Nugent; J. Parrent; M. M. Phillips; G. Pojmanski; W. Rosing; R. Ross; D. Sand; D. M. Terndrup; S. Valenti; Z. Walker; Y. Yoon

doi:10.1088/0004-637x/788/1/48

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arXiv · 1310.2241

The Man Behind the Curtain: X-rays Drive the UV through NIR Variability in the 2013 AGN Outburst in NGC 2617

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Abstract

After the All-Sky Automated Survey for SuperNovae (ASAS-SN) discovered a significant brightening of the inner region of NGC 2617, we began a ~70 day photometric and spectroscopic monitoring campaign from the X-ray through near-infrared (NIR) wavelengths. We report that NGC 2617 went through a dramatic outburst, during which its X-ray flux increased by over an order of magnitude followed by an increase of its optical/ultraviolet (UV) continuum flux by almost an order of magnitude. NGC 2617, classified as a Seyfert 1.8 galaxy in 2003, is now a Seyfert 1 due to the appearance of broad optical emission lines and a continuum blue bump. Such "changing look Active Galactic Nuclei (AGN)" are rare and provide us with important insights about AGN physics. Based on the Hbeta line width and the radius-luminosity relation, we estimate the mass of central black hole to be (4 +/- 1) x 10^7 M_sun. When we cross-correlate the light curves, we find that the disk emission lags the X-rays, with the lag becoming longer as we move from the UV (2-3 days) to the NIR (6-9 days). Also, the NIR is more heavily temporally smoothed than the UV. This can largely be explained by a simple model of a thermally emitting thin disk around a black hole of the estimated mass that is illuminated by the observed, variable X-ray fluxes.

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B. J. Shappee, J. L. Prieto, D. Grupe, C. S. Kochanek, K. Z. Stanek, G. De Rosa, S. Mathur, Y. Zu, B. M. Peterson, R. W. Pogge, S. Komossa, M. Im, J. Jencson, T. W-S. Holoien, U. Basu, J. F. Beacom, D. M. Szczygiel, J. Brimacombe, S. Adams, A. Campillay, C. Choi, C. Contreras, M. Dietrich, M. Dubberley, M. Elphick, S. Foale, M. Giustini, C. Gonzalez, E. Hawkins, D. A. Howell, E. Y. Hsiao, M. Koss, K. M. Leighly, N. Morrell, D. Mudd, D. Mullins, J. M. Nugent, J. Parrent, M. M. Phillips, G. Pojmanski, W. Rosing, R. Ross, D. Sand, D. M. Terndrup, S. Valenti, Z. Walker, Y. Yoon. 2013-10-08. The Man Behind the Curtain: X-rays Drive the UV through NIR Variability in the 2013 AGN Outburst in NGC 2617. https://doi.org/10.1088/0004-637x%2F788%2F1%2F48

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