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Title: The man behind the curtain: X-rays drive the UV through NIR variability in the 2013 active galactic nucleus outburst in NGC 2617

After the All-Sky Automated Survey for SuperNovae 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 (AGNs)' are rare and provide us with important insights about AGN physics. Based on the Hβ line width and the radius-luminosity relation, we estimate the mass of central black hole (BH) to be (4 ± 1) × 10{sup 7} M {sub ☉}. 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 bymore » a simple model of a thermally emitting thin disk around a BH of the estimated mass that is illuminated by the observed, variable X-ray fluxes.« less
Authors:
; ; ; ; ; ; ; ; ; ; ; ;  [1] ;  [2] ;  [3] ;  [4] ;  [5] ;  [6] ;  [7] ;  [8] more »; « less
  1. Department of Astronomy, The Ohio State University, Columbus, OH 43210 (United States)
  2. Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 (United States)
  3. Department of Astronomy and Astrophysics, Pennsylvania State University, 525 Davey Lab, University Park, PA 16802 (United States)
  4. Max-Planck Institut für Radioastronomie, Auf dem Hügel 69, D-53121 Bonn (Germany)
  5. CEOU/Department of Physics and Astronomy, Seoul National University, Seoul 151-742 (Korea, Republic of)
  6. Warsaw University Astronomical Observatory, Al. Ujazdowskie 4, 00-478 Warsaw (Poland)
  7. Coral Towers Observatory, Cairns, Queensland A-4870 (Australia)
  8. Carnegie Observatories, Las Campanas Observatory, Colina El Pino, Casilla 601 (Chile)
Publication Date:
OSTI Identifier:
22356663
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 788; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; BLACK HOLES; EMISSION; GALAXIES; GALAXY NUCLEI; LINE WIDTHS; LUMINOSITY; MASS; NEAR INFRARED RADIATION; SUPERNOVAE; ULTRAVIOLET RADIATION; VISIBLE RADIATION; WAVELENGTHS; X RADIATION