Bibcode
Mathur, S.; Gupta, A.; Page, K.; Pogge, R. W.; Krongold, Y.; Goad, M. R.; Adams, S. M.; Anderson, M. D.; Arévalo, P.; Barth, A. J.; Bazhaw, C.; Beatty, T. G.; Bentz, M. C.; Bigley, A.; Bisogni, S.; Borman, G. A.; Boroson, T. A.; Bottorff, M. C.; Brandt, W. N.; Breeveld, A. A.; Brown, J. E.; Brown, J. S.; Cackett, E. M.; Canalizo, G.; Carini, M. T.; Clubb, K. I.; Comerford, J. M.; Coker, C. T.; Corsini, E. M.; Crenshaw, D. M.; Croft, S.; Croxall, K. V.; Dalla Bontà, E.; Deason, A. J.; Denney, K. D.; De Lorenzo-Cáceres, A.; De Rosa, G.; Dietrich, M.; Edelson, R.; Ely, J.; Eracleous, M.; Evans, P. A.; Fausnaugh, M. M.; Ferland, G. J.; Filippenko, A. V.; Flatland, K.; Fox, O. D.; Gates, E. L.; Gehrels, N.; Geier, S.; Gelbord, J. M.; Gorjian, V.; Greene, J. E.; Grier, C. J.; Grupe, D.; Hall, P. B.; Henderson, C. B.; Hicks, S.; Holmbeck, E.; Holoien, T. W.-S.; Horenstein, D.; Horne, Keith; Hutchison, T.; Im, M.; Jensen, J. J.; Johnson, C. A.; Joner, M. D.; Jones, J.; Kaastra, J.; Kaspi, S.; Kelly, B. C.; Kelly, P. L.; Kennea, J. A.; Kim, M.; Kim, S.; Kim, S. C.; King, A.; Klimanov, S. A.; Kochanek, C. S.; Korista, K. T.; Kriss, G. A.; Lau, M. W.; Lee, J. C.; Leonard, D. C.; Li, M.; Lira, P.; Ma, Z.; MacInnis, F.; Manne-Nicholas, E. R.; Malkan, M. A.; Mauerhan, J. C.; McGurk, R.; McHardy, I. M.; Montouri, C.; Morelli, L.; Mosquera, A.; Mudd, D.; Muller-Sanchez, F.; Musso, R.; Nazarov, S. V. et al.
Bibliographical reference
The Astrophysical Journal, Volume 846, Issue 1, article id. 55, 9 pp. (2017).
Advertised on:
9
2017
Journal
Citations
36
Refereed citations
34
Description
During the Space Telescope and Optical Reverberation Mapping Project
observations of NGC 5548, the continuum and emission-line variability
became decorrelated during the second half of the six-month-long
observing campaign. Here we present Swift and Chandra X-ray spectra of
NGC 5548 obtained as part of the campaign. The Swift spectra show that
excess flux (relative to a power-law continuum) in the soft X-ray band
appears before the start of the anomalous emission-line behavior, peaks
during the period of the anomaly, and then declines. This is a
model-independent result suggesting that the soft excess is related to
the anomaly. We divide the Swift data into on- and off-anomaly spectra
to characterize the soft excess via spectral fitting. The cause of the
spectral differences is likely due to a change in the intrinsic spectrum
rather than to variable obscuration or partial covering. The Chandra
spectra have lower signal-to-noise ratios, but are consistent with the
Swift data. Our preferred model of the soft excess is emission from an
optically thick, warm Comptonizing corona, the effective optical depth
of which increases during the anomaly. This model simultaneously
explains all three observations: the UV emission-line flux decrease, the
soft-excess increase, and the emission-line anomaly.
Related projects
Formation and Evolution of Galaxies: Observations in Infrared and other Wavelengths
This IAC research group carries out several extragalactic projects in different spectral ranges, using space as well as ground-based telescopes, to study the cosmological evolution of galaxies and the origin of nuclear activity in active galaxies. The group is a member of the international consortium which built the SPIRE instrument for the
Ismael
Pérez Fournon
Traces of Galaxy Formation: Stellar populations, Dynamics and Morphology
We are a large, diverse, and very active research group aiming to provide a comprehensive picture for the formation of galaxies in the Universe. Rooted in detailed stellar population analysis, we are constantly exploring and developing new tools and ideas to understand how galaxies came to be what we now observe.
Ignacio
Martín Navarro