Scattered nuclear continuum and broad H alpha in Cygnus A

被引:50
作者
Ogle, PM
Cohen, MH
Miller, JS
Tran, HD
Fosbury, RAE
Goodrich, RW
机构
[1] UNIV CALIF SANTA CRUZ,LICK OBSERV,UCO,SANTA CRUZ,CA 95064
[2] EUROPEAN SO OBSERV,SPACE TELESCOPE EUROPEAN COORDINATING FACIL,D-85748 GARCHING,GERMANY
[3] WM KECK OBSERV,KAMUELA,HI 96743
[4] EUROPEAN SPACE AGCY,DEPT SPACE SCI,DIV ASTROPHYS,F-75738 PARIS 15,FRANCE
关键词
galaxies; active; individual (Cygnus A);
D O I
10.1086/310675
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
We have discovered scattered broad Balmer emission lines in the spectrum of Cygnus A, using the Keek II Telescope. Broad Her 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 active galactic nucleus light provides a significant contribution to the total flux at 3800 Angstrom (rest) of the western component, where the polarization rises to 16%. The spatially integrated flux of Cygnus A at 5500 Angstrom 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 that corresponds to the ionization cone seen in Hubble Space Telescope images. Our results are consistent with scattering of light from a hidden quasar of modest luminosity by an extended, dusty narrow-line region.
引用
收藏
页码:L37 / L40
页数:4
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