Multiple BeppoSAX observations of IC 4329A to probe the origin of the Compton reflection component in Seyfert 1 galaxies

IC 4329A is the brightest known Seyfert galaxy in hard (∼2–30 keV) X-rays and is likely to be representative of Seyfert 1 galaxies as a class. A recent 100 ks BeppoSAX observation (Perola et al. 1999) clearly confirmed the presence of a warm absorber, a reflection component $(\mathrm{R}\text{∼0.6),}$ and a high-energy cut-off in the power law at ${\mathrm{E}}_c\text{∼270\hspace{0.17em}}\mathrm{keV}.$ Its richness in spectral features, combined with its large flux (${\text{∼1.6×10}}^{\text{−10}}\hspace{0.17em}{\mathrm{erg\hspace{0.17em}cm}}^{\text{−2}} {\mathrm{s}}^{\text{−1}}$ between 2–10 keV), make this target ideal for multiple observations (in particular with BeppoSAX) to search for spectral variations. Results obtained from 3 follow-up observations (40 ks each) are presented here. The first and most important goal of this study was to probe the origin of the Compton reflection component observed in Seyfert galaxies by monitoring the variability of the reflection continuum and Fe Kα line in response to primary continuum variations. The second goal was to search for variability in the high energy cutoff. We obtain however no conclusive results on any of these issues. In fact, all four observations unfortunately caught the source at almost the same flux, showing only little, and marginal, spectral changes between different observations.