J/ApJ/788/48 X-ray through NIR photometry of NGC 2617 (Shappee+, 2014)
The man behind the curtain: X-rays drive the UV through NIR variability in
the 2013 active galactic nucleus outburst in NGC 2617.
Shappee B.J., Prieto J.L., Grupe D., Kochanek C.S., Stanek K.Z.,
De Rosa G., Mathur S., Zu Y., Peterson B.M., Pogge R.W., Komossa S., Im M.,
Jencson J., Holoien T.W-S., Basu U., Beacom J.F., Szczygiel D.M.,
Brimacombe J., Adams S., Campillay A., Choi C., Contreras C., Dietrich M.,
Dubberley M., Elphick M., Foale S., Giustini M., Gonzalez C., Hawkins E.,
Howell D.A., Hsiao E.Y., Koss M., Leighly K.M., Morrell N., Mudd D.,
Mullins D., Nugent J.M., Parrent J., Phillips M.M., Pojmanski G.,
Rosing W., Ross R., Sand D., Terndrup D.M., Valenti S., Walker Z., Yoon Y.
<Astrophys. J., 788, 48 (2014)>
=2014ApJ...788...48S 2014ApJ...788...48S (SIMBAD/NED BibCode)
ADC_Keywords: Active gal. nuclei ; Galaxies, Seyfert ; X-ray sources ;
Photometry, UBVRIJKLMNH ; Photometry, SDSS
Keywords: galaxies: active - galaxies: nuclei - galaxies: Seyfert -
line: formation - line: profiles
Abstract:
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)x107 M☉. 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 BH of the estimated mass that is illuminated by the
observed, variable X-ray fluxes.
Description:
On 2013 April 10.27, a transient source alert was triggered by the
brightening of the central region of NGC 2617. Follow-up observations
confirmed that the nucleus was the source of the outburst and a
follow-up spectrum showed that the source now has the strong broad
emission lines and continuum shape characteristic of a Seyfert 1.
Given the strong outburst and dramatic change in the spectral
properties, we requested and obtained Swift (Gehrels et al.
2004ApJ...611.1005G 2004ApJ...611.1005G) target of opportunity (ToO) observations to
monitor NGC 2617 in the optical, UV, and X-rays, which found that NGC 2617
continued to brighten. During this outburst we were able to obtain an
extensive time series of optical spectroscopy and NIR/optical/UV/X-ray
photometry that are presented in this paper.
Objects:
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RA (ICRS) DE Designation(s)
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08 35 38.78 -04 05 17.3 NGC 2617 = 2MASX J08353877-0405172
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 52 528 Photometric Observations
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See also:
VII/173 : Catalogue of Seyfert Galaxies (Lipovetsky+, 1988)
II/339 : Swift/UVOT Serendipitous Source Catalog (Yershov, 2015)
J/ApJ/705/14 : Seyfert galaxies in the mid-IR (Deo+, 2009)
J/ApJ/713/L11 : X-ray properties of Seyfert 1 galaxies (Zhou+, 2010)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 8 F8.3 d JD Julian Date of the observation (JD-2450000)
10- 21 A12 --- Band Observational band
23- 27 F5.2 mag mag ? Observed magnitude (1)
29- 32 F4.2 mag e_mag ? Uncertainty in mag
34- 37 F4.2 10-14W/m2 FX ? X-ray flux (2)
39- 42 F4.2 10-14W/m2 e_FX ? Uncertainty in FX
44- 47 F4.2 --- Gamma ? Photon Index; X-ray data only
49- 52 F4.2 --- e_Gamma ? Uncertainty in Gamma
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Note (1): Magnitudes with the Swift, U, B, V, R, I, Z, Y, J, H, and K-band
photometry are calibrated in the Vega magnitude system. u, g, r, and
i-band photometry are calibrated in the AB magnitude system.
Note (2): The units of the Swift 0.3-10 keV X-ray fluxes (first 41 data rows)
are in 10-11 erg/s/cm2.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Tiphaine Pouvreau [CDS] 06-Jul-2017