X-ray/UV campaign on the Mrk 279 outflow

Density diagnostics in active galactic nuclei using O v K-shell absorption lines

J. S. Kaastra, A. J J Raassen, R. Mewe, N. Arav, E. Behar, E. Costantini, Jack Gabel, G. A. Kriss, D. Proga, M. Sako, K. C. Steenbrugge

Research output: Contribution to journalArticle

28 Citations (Scopus)

Abstract

One of the main problems in modeling the ionised outflows in Active Galactic Nuclei is the unknown distance of the outflowing wind to the central source. Only if the density is known this distance can be determined through the ionisation parameter. Here we study density diagnostics based upon O V transitions. O V is known to have metastable levels that are density dependent. We study the population of those levels under photoionisation equilibrium conditions and determine for which parameter range they can have a significant population. We find that resonance line trapping plays an important role in reducing the critical densities above which the metastable population becomes important. We investigate the K-shell absorption lines from these metastable levels. Provided that there is a sufficient population of the metastable levels, the corresponding K-shell absorption lines are detectable and are well separated from the main absorption line originating from the ground state. We then present the Chandra LETGS spectrum of the Seyfert 1 galaxy Mrk 279 that may show for the first time the presence of these metastable level absorption lines. A firm identification is not yet possible due to both uncertainties in the observed wavelength of the strongest line as well as uncertainties in the predicted wavelength. If the line is indeed due to absorption from O v, then we deduce a distance to the central source of one light week to a few light months, depending upon the importance of additional heating processes.

Original languageEnglish
Pages (from-to)57-66
Number of pages10
JournalAstronomy and Astrophysics
Volume428
Issue number1
DOIs
StatePublished - Dec 2004
Externally publishedYes

Fingerprint

active galactic nuclei
outflow
shell
x rays
wavelength
resonance lines
wavelengths
trapping
photoionization
ionization
galaxies
heating
ground state
modeling
parameter

All Science Journal Classification (ASJC) codes

  • Space and Planetary Science

Cite this

Kaastra, J. S., Raassen, A. J. J., Mewe, R., Arav, N., Behar, E., Costantini, E., ... Steenbrugge, K. C. (2004). X-ray/UV campaign on the Mrk 279 outflow: Density diagnostics in active galactic nuclei using O v K-shell absorption lines. Astronomy and Astrophysics, 428(1), 57-66. https://doi.org/10.1051/0004-6361:20041434

X-ray/UV campaign on the Mrk 279 outflow : Density diagnostics in active galactic nuclei using O v K-shell absorption lines. / Kaastra, J. S.; Raassen, A. J J; Mewe, R.; Arav, N.; Behar, E.; Costantini, E.; Gabel, Jack; Kriss, G. A.; Proga, D.; Sako, M.; Steenbrugge, K. C.

In: Astronomy and Astrophysics, Vol. 428, No. 1, 12.2004, p. 57-66.

Research output: Contribution to journalArticle

Kaastra, JS, Raassen, AJJ, Mewe, R, Arav, N, Behar, E, Costantini, E, Gabel, J, Kriss, GA, Proga, D, Sako, M & Steenbrugge, KC 2004, 'X-ray/UV campaign on the Mrk 279 outflow: Density diagnostics in active galactic nuclei using O v K-shell absorption lines', Astronomy and Astrophysics, vol. 428, no. 1, pp. 57-66. https://doi.org/10.1051/0004-6361:20041434
Kaastra, J. S. ; Raassen, A. J J ; Mewe, R. ; Arav, N. ; Behar, E. ; Costantini, E. ; Gabel, Jack ; Kriss, G. A. ; Proga, D. ; Sako, M. ; Steenbrugge, K. C. / X-ray/UV campaign on the Mrk 279 outflow : Density diagnostics in active galactic nuclei using O v K-shell absorption lines. In: Astronomy and Astrophysics. 2004 ; Vol. 428, No. 1. pp. 57-66.
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