An outburst scenario for the X-ray spectral variability in 3C 111

Abstract

We present a combined Suzaku and Swift BAT broad-band E = 0.6-200 keV spectral analysis of three 3C 111 observations obtained in 2010. The data are well described with an absorbed power-law continuum and a weak (R {minus tilde} 0.2) cold reflection component from distant material. We constrain the continuum cutoffat EC {minus tilde} 150-200 keV, which is in accordance with X-ray Comptonization corona models and supports claims that the jet emission is only dominant at much higher energies. Fe XXVI Lyα emission and absorption lines are also present in the first and second observations, respectively. The modelling and interpretation of the emission line is complex and we explore three possibilities. If originating from ionized-disc reflection, this should be emitted at rin = 50 rg or, in the lamp-post configuration, the illuminating source should be at a height of h=30 rg above the black hole. Alternatively, the line could be modelled with a hot collisionally ionized plasma with temperature kT = 22.0+6.1-3.2 keV or a photoionized plasma with log ξ = 4.52+0.10-0.16 erg s-1 cm and column density NH> 3 × 1023 cm-2. However, the first and second scenarios are less favoured on statistical and physical grounds, respectively. The blueshifted absorption line in the second observation can be modelled as an ultrafast outflow (UFO) with ionization parameter log ξ = 4.47+0.76-0.04erg s-1 cm, column density NH = (5.3+1.8-1.3) × 1022 cm-2 and outflow velocity νout = 0.104 ± 0.006c. Interestingly, the parameters of the photoionized emission model remarkably match those of the absorbing UFO, supporting the possibility that the same material could be responsible for both emission and absorption. We suggest an outburst scenario in which an accretion disc wind, initially lying out of the line of sight and observed in emission, then crosses our view to the source and it is observed in absorption as a mildly relativistic UFO. © 2013 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society.