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

By J. Reeves, C. Done, K. Pounds, Y. Terashima, K. Hayashida, N. Anabuki. 2008

133 citations recorded by the source corpus.

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 × 103 cm−3, while the absorber column is 5 × 1022 < NH < 1 × 1024 cm−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.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/9979b44d911c80bac463c6c02c04972885db3763

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In Astronomy and Astrophysics

1. D. M. Alexander
2. A. King
3. K. Pounds
4. C. Ricci
5. E. Treister
6. Kevin Schawinski
7. M. Cappi
8. Y. Ueda

Citations in the corpus

• DISCOVERY OF ULTRA-FAST OUTFLOWS IN A SAMPLE OF BROAD-LINE RADIO GALAXIES OBSERVED WITH SUZAKU (2010, background): “Similar conclusions were reached by Reeves et al. (2008) concerning the bright quasar PG 1211+143.”
• BAT AGN Spectroscopic Survey. V. X-Ray Properties of the Swift/BAT 70-month AGN Catalog (2017, methodology): “The values of NH from the best-fit models are listed in TableC3 Absorption by ionized gas (also referred to as “warm absorption”) was taken into account using the zxipcf model (Reeves et al. 2008), which uses a grid of XSTAR absorption models (Bautista & Kallman 2001; Kallman & Bautista 2001).”
• Powerful Outflows and Feedback from Active Galactic Nuclei (2015, background): “…however, by a revised velocity of 0.13− 0.15c based on the inclusion of additional absorption lines from intermediate–mass ions (Pounds & Page 2006), and when repeated observations of PG1211+143 demonstrated that the strong Fe K absorption line was variable over several years (Reeves et al. 2008).”
• Evidence for ultra-fast outflows in radio-quiet AGNs - I. Detection and statistical incidence of Fe K-shell absorption lines (2010, background): “…2009); Mrk 79 in EW on∆t <∼ 1 month; NGC 4051 in both EW and velocity on∆t <∼ 1.5 yrs; Mrk 766 in EW on∆t <∼ 2 days (<∼ 150–200 ks) and in velocity on<∼ 4 days (<∼ 300–400 ks); Mrk 841 in EW on<∼ 6 months; PG 1211+143 in EW ∆t <∼ 3 yrs (e.g., Reeves et al. 2008); MCG-5-23-16 in EW on∆t <∼ 4 yrs.”
• The Suzaku View of Highly Ionized Outflows in AGN. 1; Statistical Detection and Global Absorber Properties (2012, methodology): “Outflows in 3C 445 and PG 1211+143 have been detected with other observatories (3C 445: Reeves et al. 2010, PG 1211+143: Pounds et al. 2003b) and they are known to be intrinsically variable, being weakest in their respective Suzaku observations (Reeves et al. 2008b; Braito et al. 2011).”