DETERMINING INCLINATIONS OF ACTIVE GALACTIC NUCLEI VIA THEIR NARROW-LINE REGION KINEMATICS. I. OBSERVATIONAL RESULTS

Abstract

Active Galactic Nuclei (AGN) are axisymmetric systems to first order; their\nobserved properties are likely strong functions of inclination with respect to\nour line of sight. However, except for a few special cases, the specific\ninclinations of individual AGN are unknown. We have developed a promising\ntechnique for determining the inclinations of nearby AGN by mapping the\nkinematics of their narrow-line regions (NLRs), which are often easily resolved\nwith Hubble Space Telescope (HST) [O III] imaging and long-slit spectra from\nthe Space Telescope Imaging Spectrograph (STIS). Our studies indicate that NLR\nkinematics dominated by radial outflow can be fit with simple biconical outflow\nmodels that can be used to determine the inclination of the bicone axis, and\nhence the obscuring torus, with respect to our line of sight. We present NLR\nanalysis of 53 Seyfert galaxies and resultant inclinations from models of 17\nindividual AGN with clear signatures of biconical outflow. Our model results\nagree with the unified model in that Seyfert 1 AGN have NLRs inclined further\ntoward our line of sight (LOS) than Seyfert 2 AGN. Knowing the inclinations of\nthese AGN NLRs, and thus their accretion disk and/or torus axes, will allow us\nto determine how their observed properties vary as a function of polar angle.\nWe find no correlation between the inclinations of the AGN NLRs and the disks\nof their host galaxies, indicating that the orientation of the gas in the torus\nis independent from that of the host disk.\n