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|Title:||X-ray time delays from the Seyfert 2 galaxy IRAS 18325−5926|
|Authors:||Vaughan, S. A.|
Lobban, A. P.
|Publisher:||Oxford University Press (OUP)|
|Citation:||Monthly Notices of the Royal Astronomical Society, 2014, 445 (3), pp. 3229-3238|
|Abstract:||Using new XMM–Newton observations we detect hard X-ray time lags in the rapid variability of the Compton-thin Seyfert 2 galaxy IRAS 18325−5926. The higher-energy X-ray variations lag behind correlated lower-energy variations by up to ∼3 ks and the magnitude of the lag increases clearly with energy separation between the energy bands. We find that the lag-energy spectrum has a relatively simple log (E) shape. This is quite different in both shape and magnitude from the lags predicted by simple reflection models, but very similar to the hard X-ray lags often seen in black hole X-ray binaries. We apply several spectral models to the lag-energy spectrum and rule out simple reflection as an origin for the hard lags. We find that both propagating fluctuations embedded in the accretion flow and electron scattering from material embedded in or behind a cold absorbing medium offer equally good fits to the observed low-frequency hard X-ray lags and are both consistent with the time-averaged spectrum. Such models will likely look very different outside of XMM–Newton's observable bandpass, paving the way for future studies with NuSTAR.|
|Rights:||This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society ©: 2014 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved. Deposited with reference to the publisher’s archiving policy available on the SHERPA/RoMEO website.|
|Appears in Collections:||Published Articles, Dept. of Physics and Astronomy|
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