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The flux-dependent X-ray time lags in NGC 4051

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posted on 2016-02-10, 11:40 authored by W. N. Alston, Simon Allan Vaughan, P. Uttley
We present an analysis of the X-ray time lags for the highly variable Seyfert 1 galaxy NGC 4051, based on a series of XMM–Newton observations taken in 2009. We investigate the Fourier frequency dependent time lags in the light curves between the 0.3–1.0 keV and 2.0–5.0 keV energy bands as a function of source flux, including simultaneous modelling of the resulting lag-frequency spectra. We find the shape of the lag-frequency spectra to vary significantly and systematically with source flux. We model the lag-frequency spectra using simple transfer functions, and find that two time lag components are required, one in each energy band. The simplest acceptable fits have only the relative contribution of the lagged component in the hard band varying with flux level, which can be associated with changes in the energy spectrum. We discuss the interpretation of these results in terms of the currently popular models for X-ray time lags.

History

Citation

Monthly Notices of the Royal Astronomical Society, 2013, 435 (2), pp. 1511-1519

Author affiliation

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

Version

  • VoR (Version of Record)

Published in

Monthly Notices of the Royal Astronomical Society

Publisher

Oxford University Press (OUP)

issn

0035-8711

eissn

1365-2966

Acceptance date

2013-07-24

Copyright date

2013

Available date

2016-02-10

Publisher version

http://mnras.oxfordjournals.org/content/435/2/1511

Language

en

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