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A compact, metal-rich, kpc-scale outflow in FBQS J0209-0438: detailed diagnostics from HST/COS extreme UV observations

Finn, Charles W.; Morris, Simon L.; Crighton, Neil H.M.; Hamann, Fred; Done, Chris; Theuns, Tom; Fumagalli, Michele; Tejos, Nicolas; Worseck, Gabor

A compact, metal-rich, kpc-scale outflow in FBQS J0209-0438: detailed diagnostics from HST/COS extreme UV observations Thumbnail


Charles W. Finn

Neil H.M. Crighton

Fred Hamann

Nicolas Tejos

Gabor Worseck


We present HST/COS observations of highly ionized absorption lines associated with a radio-loud quasar (QSO) at z = 1.1319. The absorption system has multiple velocity components, with an overall width of ≈600 km s−1, tracing gas that is largely outflowing from the QSO at velocities of a few 100 km s−1. There is an unprecedented range in ionization, with detections of H I, N III, N IV, N V, O IV, O IV*, O V, O VI, Ne VIII, Mg X, S V and Ar VIII. We estimate the total hydrogen number density from the column density ratio N(OIV*) / N(OIV) to be log(nH/cm−3)∼3. Combined with constraints on the ionization parameter in the O IV bearing gas from photoionization equilibrium models, we derive a distance to the absorbing complex of 2.3≲R≲6.0kpc from the centre of the QSO. A range in ionization parameter, covering ∼two orders of magnitude, suggest absorption path lengths in the range 10−4.5≲labs≲1pc. In addition, the absorbing gas only partially covers the background emission from the QSO continuum, which suggests clouds with transverse sizes ltrans≲10−2.5 pc. Widely differing absorption path lengths, combined with covering fractions less than unity across all ions pose a challenge to models involving simple cloud geometries in associated absorption systems. These issues may be mitigated by the presence of non-equilibrium effects, which can be important in small, dynamically unstable clouds, together with the possibility of multiple gas temperatures. The dynamics and expected lifetimes of the gas clouds suggest that they do not originate from close to the active galactic nuclei, but are instead formed close to their observed location. Their inferred distance, outflow velocities and gas densities are broadly consistent with scenarios involving gas entrainment or condensations in winds driven by either supernovae, or the supermassive black hole accretion disc. In the case of the latter, the present data most likely does not trace the bulk of the outflow by mass, which could instead manifest itself as an accompanying warm absorber, detectable in X-rays.


Finn, C. W., Morris, S. L., Crighton, N. H., Hamann, F., Done, C., Theuns, T., …Worseck, G. (2014). A compact, metal-rich, kpc-scale outflow in FBQS J0209-0438: detailed diagnostics from HST/COS extreme UV observations. Monthly Notices of the Royal Astronomical Society, 440(4), 3317-3340.

Journal Article Type Article
Publication Date Jun 1, 2014
Deposit Date Apr 29, 2014
Publicly Available Date Apr 30, 2014
Journal Monthly Notices of the Royal Astronomical Society
Print ISSN 0035-8711
Electronic ISSN 1365-2966
Publisher Royal Astronomical Society
Peer Reviewed Peer Reviewed
Volume 440
Issue 4
Pages 3317-3340
Keywords Galaxies, Active quasars, Absorption lines.


Published Journal Article (2.5 Mb)

Copyright Statement
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.

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