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On why the iron K-shell absorption in AGN is not a signature of the local warm/hot intergalactic medium

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posted on 08.02.2016, 11:59 by J. N. Reeves, C. Done, KAPA5 others, Kenneth Alwyne Pounds, Y. Terashima, K. Hayashida, N. Anabuki, M. Uchino, Martin Turner
We present a comparison between the 2001 XMM–Newton and 2005 Suzaku observations of the quasar, PG 1211+143, at z = 0.0809. Variability is observed in the 7 keV iron K-shell absorption line (at 7.6 keV in the quasar frame), which is significantly weaker in 2005 than during the 2001 XMM–Newton observation. From a recombination time-scale of <4 yr, this implies an absorber density n > 4 × 10[Superscript: 3] cm[Superscript: −3], while the absorber column is 5 × 10[Superscript: 22] < NH < 1 × 10[Superscript: 24] cm[Superscript: −2]. Thus, the size scale of the absorber is too compact (pc scale) and the surface brightness of the dense gas too high (by 9–10 orders of magnitude) to arise from local hot gas, such as the local bubble, group or warm/hot intergalactic medium (WHIM), as suggested by McKernan, Yaqoob & Reynolds. Instead, the iron K-shell absorption must be associated with an active galactic nucleus (AGN) outflow with mildly relativistic velocities. Finally, we show that the association of the absorption in PG 1211+143 with local hot gas is simply a coincidence, and the comparison between the recession and iron K absorber outflow velocities in other AGN does not reveal a one-to-one kinematic correlation.

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Citation

Monthly Notices of the Royal Astronomical Society Letters, 2008, 385, pp. L108-112

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 Letters

Publisher

Wiley-Blackwell

issn

1745-3933

Acceptance date

10/01/2008

Copyright date

2008

Available date

08/02/2016

Publisher version

https://mnrasl.oxfordjournals.org/content/385/1/L108.full

Language

en

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