AbstractWe present results of high S/N, high spatial and spectral resolution (0″.65 and 0.8Å FWHM, respectively) spectrophotometry of the NLR of NGC 4151 using the Keck 10-m Telescope. The observations are the first in a series that test unambiguously several specific predictions that are based on earlier modeling of spatially unresolved emissionline spectra. Importantly, we partially resolve the source of most of the emission-line flux. Thus, the observations suitably complement analyses of spatially unresolved NLR spectra.
We have obtained high signal-to-noise ratio CCD spectra at ≤ 150 km/s resolution for 6 high-ionization Seyfert galaxies. We analyzed the profiles of the emission-lines over a wide range in both ionization potential (IP) and critical density (Ncr) in order to study the fundamental problem of cloud motion in the narrow-line region (NLR). Using the known correlations between FWHM and IP and/or Ncr for these galaxies, and assuming that the blueward profile asymmetries result from the combined effects of radially infalling or outflowing clouds and extinction within or between them, we deconvolve these effects by analyzing the correlation between emission-line asymmetries and both IP and Ncr. We find fair to good correlations in the sense that lines with high IP and Ncr also tend to have high asymmetry, while lines with low IP and Ncr have low but usually non-zero asymmetry. Simulated emission-line profiles generated with a spherically-symmetric model of a NLR suggest that the extinction arises primarily within radially infalling clouds.
Cospatial Line Emission and Accelerated Outflow in the Spatially Resolved Narrow-Line Region of NGC 4151: Confirming Model Predictions