Imaging the AGN Torus in Cygnus

Abstract

We present the first direct imaging of what may be the thick torus in the active galactic nucleus (AGN) of the archetype powerful radio galaxy Cygnus A, using the Jansky Very Large Array (VLA) at 18 GHz to 48 GHz, with a resolution down to 45 mas. Such a torus has long been a key component of AGN models, but direct imaging on the relevant physical scales in sources of extreme (quasar-like) luminosities, remains scarce. An elongated structure, perpendicular to the radio jets and centered on the core, is well resolved, with a full length of $0.48"$ (528 pc), and a full width of $0.26"$ (286 pc). The radio emission spectrum is consistent with optically thin free-free emission. We present a toy model of a flaring torus, with a half-opening angle for the poloidal region of $62^o$. The radio jets are oriented along the poles. The observations require a clumpy gas distribution, with the free-free emission dominated by clumps with densities $\ge 4000$ cm${}^{-3}$

Accepted to Astrophysical Journal Letters, 10 pages, 7 figures

References in corpus (6)

• Active Galactic Nuclei: what's in a name?
• High-Velocity Bipolar Molecular Emission from an AGN Torus
• Parsec-scale dust distributions in Seyfert galaxies - Results of the MIDI AGN snapshot survey
• Discovery of a Luminous Radio Transient 460 pc from the Central Supermassive Black Hole in Cygnus A
• Polarized Mid-Infrared Synchrotron Emission in the Core of Cygnus A
• Subaru Spectroscopy and Spectral Modeling of Cygnus A

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