BBXRT observations of NGC4151: Fe K line diagnostics

Evidence for the presence of Fe Kα line emission in the X‐ray spectra of AGN has been quickly accumulating over the past few years. The Broad Band X‐ray Telescope (BBXRT) has provided us with the first high quality, medium resolution X‐ray spectral data of this potentially powerful diagnostic tool. We are able to constrain the width of the main component of the Fe Kα line in NGC4151 to be less than 160 eV FWHM (7,500 km/sec). Also, we have limited information on the shape of the line profile. Under the assumption that this feature is produced in an accretion disk, we have obtained strong constraints on relativistic disk models, which predict broadening due to Doppler and gravitational effects, as well as a strongly asymmetric line profile and a generally blueshifted peak. In contrast, the observed line in NGC4151 is not strongly asymmetric and the energy of the line peak (fit with a gaussian) is consistent with the systemic velocity of the galaxy. In this case, the disk must be essentially face‐on to expl...