A Possible Ultra Strong and Broad Fe Kα Emission Line in Seyfert 2 Galaxy IRAS 00521-7054

Abstract

We present XMM-Newton spectra of the Seyfert 2 Galaxy IRAS 00521-7054. A strong feature at ~6 keV (observer's frame) can be formally fitted with a strong (EW = 1.3 ± 0.3 keV in the rest frame) and broad Fe Kα line, extending down to 3 keV. The underlying X-ray continuum could be fitted with an absorbed power law (with Γ = 1.8 ± 0.2 and N _H = 5.9^+0.6 _-0.7 × 10²² cm^-2) plus a soft component. If due to relativistically smeared reflection by an X-ray illuminated accretion disk, the spin of the supermassive black hole (SMBH) is constrained to be 0.97^+0.03 _-0.13 (errors at 90% confidence level for one interesting parameter), and the accretion system is viewed at an inclination angle of 37° ± 4°. This would be the first type 2 active galactic nucleus reported with strong red Fe Kα wing detected which demands a fast rotating SMBH. The unusually large EW would suggest that the light bending effect is strong in this source. Alternatively, the spectra could be fitted by a dual-absorber model (though with a global χ² higher by ~6 for 283 dof) with N _H1 = 7.0 ± 0.8 × 10²² cm^-2 covering 100% of the X-ray source, and N _H2 = 21.7^+5.6 _-5.4 × 10²² cm^-2 covering 71%, which does not require an extra broad Fe Kα line.