
TY  - JOUR
A1  - Kameno, Seiji 
A1  - Inoue, Makoto 
A1  - Wajima, Kiyoaki 
A1  - Sawada-Satoh, Satoko 
A1  - Shen, Zhi-Qiang 
T1  - Free&#8211;Free Absorption and the Unified Scheme
JF  - Publications of the Astronomical Society of Australia
JO  - Publ. Astron. Soc.  Aust.
Y1  - 2003
VL  - 20
IS  - 1
SP  - 213
EP  - 221
KW  - galaxies: active &#8212; galaxies: nuclei &#8212; galaxies: jets &#8212; radio continuum: galaxies &#8212; techniques: high angular resolution
UR  - https://doi.org/10.1071/AS03037 
N2  - We report very long baseline array (VLBA) observations at 2.3, 8.4, and 15.4 GHz towards nine gigahertz peaked spectrum (GPS) sources. One Seyfert 1 galaxy, one Seyfert 2 galaxy, three radio galaxies, and four quasars were included in our survey. We obtained spatial distributions of the free&#8211;free absorption (FFA) opacity with milliarcsecond resolution for all sources. It is found that type 1 (Seyfert 1 and quasars) and type 2 (Seyfert 2 and radio galaxies) sources showed different distributions of the FFA opacities. The type 1 sources tend to show more asymmetric opacity distributions towards a double lobe, while those of the type 2 sources are rather symmetric. Our results imply that the different viewing angle of the jet causes the difference of FFA opacity along the external absorber. This idea supports the unified scheme between quasars and radio galaxies, proposed by Barthel (1989). 
ER  -

