A Suzaku survey of Fe K lines in Seyfert 1 active galactic nuclei

R. Patrick, A. (1) , N. Reeves, J. (1) , Delphine Porquet (2) , G. Markowitz, A. , V. Braito, (3) , P. Lobban, A. (1)

1 Keele University [Keele]
2 ObAS - Observatoire astronomique de Strasbourg
3 OAB - INAF - Osservatorio Astronomico di Brera

We construct full broad-band models in an analysis of Suzaku observations of nearby Seyfert 1 active galactic nuclei (AGN) (z ≤ 0.2) with exposures >50 ks and with greater than 30 000 counts in order to study their iron line profiles. This results in a sample of 46 objects and 84 observations. After a full modelling of the broad-band Suzaku and Swift-Burst Alert Telescope data (0.6-100 keV), we find complex warm absorption is present in 59 per cent of the objects in this sample which has a significant bearing upon the derived Fe K region parameters. Meanwhile 35 per cent of the 46 objects require some degree of high column density partial coverer in order to fully model the hard X-ray spectrum. We also find that a large number of the objects in the sample (22 per cent) require high velocity, high ionization outflows in the Fe K region resulting from Fe XXV and Fe XXVI. A further four AGN feature highly ionized Fe K absorbers consistent with zero outflow velocity, making a total of 14/46 (30 per cent) AGN in this sample showing evidence for statistically significant absorption in the Fe K region. Narrow Fe Kα emission from distant material at 6.4 keV is found to be almost ubiquitous in these AGN. Examining the 6-7 keV Fe K region we note that narrow emission lines originating from Fe XXV at 6.63-6.70 keV and from Fe XXVI at 6.97 keV are present in 52 and 39 per cent of objects, respectively. Our results suggest statistically significant relativistic Fe Kα emission is detected in 23 of 46 objects (50 per cent) at >99.5 per cent confidence, measuring an average emissivity index of q = 2.4 ± 0.1 and equivalent width ( EW )=96±10 eV using the RELLINE model. When parametrized with a Gaussian we find an average line energy of 6.32 ± 0.04 keV, σwidth = 0.470 ± 0.05 keV and EW =97±19 eV. Where we can place constraints upon the black hole spin parameter a, we do not require a maximally spinning black hole in all cases.

Mots clés: X-rays: galaxies; galaxies: Seyfert; black hole physics; galaxies: active

Domaines: Planète et Univers [physics]; Astrophysique [astro-ph]; Cosmologie et astrophysique extra-galactique [astro-ph.CO]; Phénomènes cosmiques de haute energie [astro-ph.HE]

R. Patrick, A., N. Reeves, J., Delphine Porquet, G. Markowitz, A., V. Braito,, et al.. A Suzaku survey of Fe K lines in Seyfert 1 active galactic nuclei. Monthly Notices of the Royal Astronomical Society, 2012, 426 (3), pp.2522-2565. ⟨10.1111/j.1365-2966.2012.21868.x⟩. ⟨hal-02327624⟩