A Study of Three-Dimensional Kinematics of the Narrow-Line Region of the Seyfert Galaxy NGC 4151 Based on Integral Field Spectroscopy

By using the Integral Field Spectroscopy mode of the Kyoto Tri-dimensional Spectrograph II we have mapped the two-dimensional distribution of kinematics in a wide variety of emission lines in the narrow-line region of NGC 4151. We decomposed the emission lines and defined two components: a narrow component and a broad component. The narrow component has smaller FWHM values, and is spatially more extended than the broad component. We applied a simple model to each component, a rotation in the galactic plane for the narrow component and a biconical outflow model for the broad one. The two-dimensional velocity distributions of the narrow component was well-fitted to a normal rotation in the galactic plane, with the best-fit parameters being similar among the emission lines. We found that the residual maps show similar large positive values at a knot around 6 00 southwest form the nucleus. For the central region, excluding the knot, the velocity field was fitted better, and the residual was small as the relative wavelength-calibration accuracy of the instrument among lenslets. We modeled the broad component with a simple biconical outflow axisymmetrical with respect to its axis by assuming a constant outflowing velocity, a constant FWHM value, and the emission line strength declining according to a power law with the distance from the nucleus. The best-fit model suggests that PA for the axis of the biconical outflow is close to the direction of the [O III] line emission elongation. Our line of sight was included within the outflowing bicone, which had filled cones.