Warm absorber, reflection, and Fe K line in the X-ray spectrum of IC 4329A

Results from the X-ray spectral analysis of the ASCA (Astro-D) performance verification (PV) phase observation of the: Seyfert 1 galaxy IC 4329A are presented. We find that the 0.4-10 keV spectrum of IC 4329A is best described by the. Sum of a steep (Gamma similar to 1.98) power-law spectrum passing through a warm absorber plus a strong reflection component and associated Fe K line, confirming recent results (Madejski et al. 1995; Mushotzky et al. 1995): Further cold absorption in excess of the Galactic value and covering the entire source is also required by the data, consistent with the edge-on galactic disk and previous X-ray measurements. The effect of the warm absorber at soft X-ray energies is best parameterized by two absorption edges, one consistent with O VI, O VII, or N VII, the other consistent with O VIII. A description of the soft excess in terms of blackbody emission, as observed in some other Seyfert 1 galaxies, is ruled out by the data. A large amount of reflection is detected in both the gas scintillation imaging spectrometer (GIS) and the solid-state imaging spectrometer (SIS) dectectors, at similar intensities. We find a strong correlation between the amount of reflection and the photon index, but argue that the best solution for the present data is that given by the best statistical fit. The model dependence of the Fe K line parameters is also discussed. Our best fit gives a slightly broad (sigma similar or equal to 0.11 +/- 0.08 keV) and redshifted (E similar or equal to 6.20 +/- 0.07 keV) Fe K line, with equivalent width (EW) similar or equal to 89 +/- 33 eV. The presence of a weak Fe K line with a strong reflection can be reconciled if one assumes iron underabundances or ionized reflection. We also have modeled the line with a theoretical line profile produced by an accretion disk. This yields results in better agreement with the constraints obtained from the reflection component.