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A. J. Young (University of Maryland), K. Iwasawa (University of Cambridge), C. S. Reynolds (University of Maryland), A. C. Fabian (University of Cambridge)
We present the results of a 120 ksec XMM-Newton observation of the Seyfert 2 galaxy IRAS 18325-5926 (Fairall 49). In the time-averaged spectrum we detect a strong, broad, ionized iron line. The X-ray light curve was variable on all timescales, including a large flare in which the X-ray flux increased by a factor of approximately two. At the onset of this large flare we find the hard X-rays rise almost 2000 sec after the soft X-rays. After the flare the hard X-rays decay more slowly than the soft X-rays. Smaller flares show different behavior, with the hard and soft X-rays rising together, and the hard X-rays subsequently decaying more slowly than the soft X-rays. It is possible that these time delays are caused by inverse-Compton scattering in a relatively cool corona. In addition, the iron line and iron edge are variable on timescales as short as 1000 sec, and the equivalent width of the iron line does not track the continuum flux. Understanding these observations is a challenge for models of the inner tens of Schwarzschild radii of accretion flows around black holes. We appreciate support from NASA under grant NAG5-9935.
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Bulletin of the American Astronomical Society,
© 2003. The American Astronomical Soceity.