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arXiv · astro-ph/0104039

The Dense Plasma Torus Around the Nucleus of an Active Galaxy NGC 1052

S. Kameno·S. Sawada-Satoh·M. Inoue·Z. -Q. Shen·K. Wajima
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Abstract

A subparsec-scale dense plasma torus around an active galactic nucleus (AGN) is unveiled. We report on very-long-baseline interferometry (VLBI) observations at 2.3, 8.4, and 15.4 GHz towards the active galaxy NGC 1052. The convex spectra of the double-sided jets and the nucleus imply that synchrotron emission is obscured through free--free absorption (FFA) by the foreground cold dense plasma. A trichromatic image was produced to illustrate the distribution of the FFA opacity. We found a central condensation of the plasma which covers about 0.1 pc and 0.7 pc of the approaching and receding jets, respectively. A simple explanation for the asymmetric distribution is the existence of a thick plasma torus perpendicular to the jets. We also found an ambient FFA absorber, whose density profile can be ascribed to a spherical distribution of the isothermal King model. The coexistence of torus-like and spherical distributions of the plasma suggests a transition from radial accretion to rotational accretion around the nucleus.

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S. Kameno, S. Sawada-Satoh, M. Inoue, Z. -Q. Shen, K. Wajima. 2001-04-03. The Dense Plasma Torus Around the Nucleus of an Active Galaxy NGC 1052. https://doi.org/10.1093/pasj%2F53.2.169

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