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X-ray time lags in PG 1211+143

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journal contribution
posted on 25.05.2018, 14:55 by A. P. Lobban, S. A. Vaughan, K. Pounds, J. Reeves
We investigate the X-ray time lags of a recent ∼630 ks XMM–Newton observation of PG 1211+143. We find well-correlated variations across the XMM–Newton EPIC bandpass, with the first detection of a hard lag in this source with a mean time delay of up to ∼3 ks at the lowest frequencies. We find that the energy-dependence of the low-frequency hard lag scales approximately linearly with log(E) when averaged over all orbits, consistent with the propagating fluctuations model. However, we find that the low-frequency lag behaviour becomes more complex on time-scales longer than a single orbit, suggestive of additional modes of variability. We also detect a high-frequency soft lag at ∼10−4 Hz with the magnitude of the delay peaking at ≲ 0.8 ks, consistent with previous observations, which we discuss in terms of small-scale reverberation.


This research has made use of the NASA Astronomical Data System (ADS), the NASA Extragalactic Database (NED) and is based on observations obtained with XMM–Newton, an ESA science mission with instruments and contributions directly funded by ESA Member States and NASA. This research is also based on observations with the NASA/UKSA/ASI mission Swift. APL acknowledges support from STFC consolidated grant ST/M001040/1 and JNR acknowledges financial support via NASA grant NNX15AF12G.



Monthly Notices of the Royal Astronomical Society, 2018, 476 (1), pp. 225-234 (10)

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/Organisation/COLLEGE OF SCIENCE AND ENGINEERING/Department of Physics and Astronomy


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Monthly Notices of the Royal Astronomical Society


Oxford University Press (OUP), Royal Astronomical Society





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