A possible ultra strong and broad Fe Ka emission line in Seyfert 2 galaxy IRAS 00521-7054

Ying Tan, Junxian Wang, Xinwen Shu, Youyuan Zhou

Published 2012-02-02Version 1

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 Ka line, extending down to 3 keV. The underlying X-ray continuum could be fitted with an absorbed powerlaw (with Gamma = 1.8+-0.2 and N_H = 5.9 x 10^22 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 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 degree. This would be the first type 2 AGN reported with strong red Fe Ka 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 chi^2 higher by ~ 6 for 283 d.o.f) with N_H1 = 7.0 x 10^22 cm^-2 covering 100% of the X-ray source, and N_H2 = 21.7 x 10^22 cm^-2 covering 71%, which does not require an extra broad Fe Ka line.