Spectroscopy of the near-nuclear regions of Cygnus A: estimating the mass of the supermassive black hole

摘要: We use a combination of high spatial resolution optical and near-infrared spectroscopic data to make detailed study the kinematics narrow-line region (NLR) gas in near-nuclear regions powerful, FRIIradio galaxy Cygnus A (z = 0.0560), with overall goal placing limits on mass any supermassive black hole core. Our K-band infrared observations (0.75-arcsec seeing) - taken NIRSPEC Keck II telescope show smooth rotation pattern across nucleus Paa H 2 emission lines along slit position (PA180°) close perpendicular radio axis, however, there is no evidence for such axis (PA105°). Higher [O III] λ5007 line -- STIS Hubble Space Telescope (HST) confirm general direction provide steep velocity gradients within radius 0.1 arcsec core corresponding surface brightness structure visible high-resolution narrow-band images. The IH] remains broad throughout (FWHM ∼ 300-900 km s 1 ), but distribution provides an unresolved inner (INLR). Assuming that ionized circularly rotating thin disc large linewidths are due activity-induced turbulence, circular velocities measured from both HST lead estimate 2.5 ′ 0.7 x 10 9 M O .. For host properties A, this consistent global correlations between deduced non-active galaxies. Therefore, despite extreme power its source quasar-like luminosity active galactic (AGN), not unusually massive considering galaxy. Indeed, estimated similar inferred FRI M87, fact AGN jets two three orders magnitude more powerful. Overall, these results idea powers galaxies determined as much by accretion rates absolute masses their holes. As well providing our also demonstrate nuclear activity has important effect circumnuclear subkiloparsec scale. Most notably, offsets outer HST/STIS positions presence outflow NW cone.