Detection of blueshifted emission and absorption and a relativistic iron line in the X-ray spectrum of ESO323-G077

We report on the X-ray observation of the Seyfert 1 galaxy ESO323-G077 performed with XMM-Newton. The EPIC spectra show a complex spectrum with conspicuous absorption and emission features. The continuum emission can be modelled with a power law with an index of 1.99 +/- 0.02 in the whole XMM-Newton energy band, marginally consistent with typical values of type I objects. An absorption component with an uncommonly high equivalent hydrogen column (n_H = 5.82^+0.12_-0.11 × 10²²cm^-2) is affecting the soft part of the spectrum. Additionally, two warm absorption components are also present in the spectrum. The lower ionized one, mainly imprinting the soft band of the spectrum, has an ionization parameter of logU = 2.14^+0.06_-0.07 and an outflowing velocity of v = 3200⁺⁶⁰⁰_-200kms^-1. Two absorption lines located at ~6.7 and ~7.0keV can be modelled with the highly ionized absorber. The ionization parameter and outflowing velocity of the gas measured are logU = 3.26^+0.19_-0.15 and v = 1700⁺⁶⁰⁰_-400kms^-1, respectively. Four emission lines were also detected in the soft energy band. The most likely explanation for these emission lines is that they are associated with an outflowing gas with a velocity of ~2000kms^-1. The data suggest that the same gas which is causing the absorption could also being responsible of these emission features. Finally, the XMM-Newton spectrum shows the presence of a relativistic iron emission line likely originated in the accretion disc of a Kerr black hole with an inclination of ~25°. We propose a model to explain the observed X-ray properties which invokes the presence of a two-phase outflow with cone-like structure and a velocity of the order of 2000- 4000kms^-1. The inner layer of the cone would be less ionized, or even neutral, than the outer layer. The inclination angle of the source would be lower than the opening angle of the outflowing cone.

Partially based on observations obtained with XMM-Newton, an ESA science mission with instruments and contributions directly funded by ESA Member States and NASA.

E-mail: elena@astroscu.unam.mx