Scattered Nuclear Continuum and Broad H$\alpha$ in Cygnus A

P. M. Ogle, M. H. Cohen
Mail Stop 105-24, California Institute of Technology, Pasadena, 
       CA 91125
Electronic mail: pmo@astro.caltech.edu

J. S. Miller, H. D. Tran
UCO/Lick Observatory, University of California, Santa Cruz, 
       CA 95064
Current address: Institute of Geophysics and Planetary 
       Physics, Lawrence Livermore National Laboratory L-413, Livermore, CA 
       94550
       
R. A. E. Fosbury
Space Telescope--European Coordinating Facility, Karl-Schwarzschild 
       Str. 2, D-85748, Garching bei Munchen, Germany
Affiliated to the Astrophysics Division, Space Science 
       Department, European Space Agency.
       
R. W. Goodrich
The W.M. Keck Observatory, 65-1120 Mamalahoa Highway, Kamuela, HI
       96743


Abstract

We have discovered scattered broad Balmer emission lines in the spectrum of 
Cygnus A, using the Keck II telescope. Broad H$\alpha$ appears in polarized 
flux from components on either side of the nucleus, and to a lesser extent in 
the nucleus. The full-width at half-maximum of broad H$\alpha$ is 26,000 km 
s$^{-1}$, comparable to the widest emission lines seen in broad-line radio 
galaxies. Scattered AGN light provides a significant contribution to the total
flux  at 3800~\AA ~(rest) of the western component, where the polarization 
rises to 16\%. The spatially integrated flux of Cygnus A at 5500~\AA ~can
be decomposed into an elliptical galaxy fraction ($F_g$=0.70), a highly
polarized blue component (FC1=0.15), a less polarized red component (FC=0.09),
and a contribution from the nebular continuum (0.06). Imaging polarimetry 
shows a double fan of polarization vectors with circular symmetry which 
corresponds to the ionization cone seen in HST images. Our results are 
consistent with scattering of light from a hidden quasar of modest luminosity 
by an extended, dusty narrow-line region.