University of Leicester
MNRAS-2012-Pounds-165-75.upload.pdf (770.3 kB)

An extended XMM–Newton observation of the Seyfert galaxy NGC 4051 – III. Fe K emission and absorption

Download (770.3 kB)
journal contribution
posted on 2016-02-08, 11:36 authored by Kenneth Alwyne Pounds, Simon Vaughan
An extended XMM–Newton observation of the Seyfert 1 galaxy NGC 4051 in 2009 detected a photoionized outflow with a complex absorption-line velocity structure and a broad correlation of velocity with ionization parameter, shown by Pounds & Vaughan to be consistent with a highly ionized, high-velocity wind running into the interstellar medium or previous ejecta, losing much of its kinetic energy in the resultant strong shock. In this paper, we examine the Fe K spectral region in more detail and find support for two distinct velocity components in the highly ionized absorber, with values corresponding to the putative fast wind (∼0.12c) and the post-shock flow (v∼ 5000–7000 km s[Superscript: −1]). The Fe K absorption-line structure is seen to vary on a orbit-to-orbit time-scale, apparently responding to both a short-term increase in ionizing flux and – perhaps more generally – to changes in the soft X-ray (and simultaneous ultraviolet) luminosity. The latter result is particularly interesting in providing independent support for the existence of shocked gas being cooled primarily by Compton scattering of accretion disc photons. The Fe K emission is represented by a narrow fluorescent line from near-neutral matter, with a weak red wing modelled here by a relativistic diskline. The narrow line flux is quasi-constant throughout the 45-d 2009 campaign, but is resolved, with a velocity width consistent with scattering from a component of the post-shock flow. Evidence for a P Cygni profile is seen in several individual orbit spectra for resonance transitions in both Fe xxv and Fe xxvi.



Monthly Notices of the Royal Astronomical Society, 2012, 423, pp. 165-175 (11)

Author affiliation

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


  • VoR (Version of Record)

Published in

Monthly Notices of the Royal Astronomical Society


Oxford University Press (OUP)





Acceptance date


Copyright date


Available date


Publisher version



Usage metrics

    University of Leicester Publications