NGC 4151: An Intrinsically Average Seyfert 1

We present a detailed analysis of a long, 100 ks observation of NGC 4151 by ASCA , contemporaneous with an observation by CGRO /OSSE. We fit the data with physical models including an Fe K line and Compton reflection both relativistically broadened and coupled according to theoretical results. The model also includes a narrow Fe K component, which is emitted by both an extended plasma region and the X-ray absorber. Our study of the absorber shows strong evidence for the presence of more than one partial-covering cloud in the line of sight. Taking these points into account, our best intrinsic model includes a Comptonization continuum with an X-ray slope of Γ ≃ 1.9 from a thermal plasma with an electron kT ~ 70 keV and a disk line with an equivalent width of ~70 eV. The broadening of the line and reflection indicate their origin from innermost parts of an accretion disk. Our results indicate that NGC 4151 has an intrinsic X-ray spectrum and variability properties similar to those of average Seyfert 1 galaxies.