How much do we know about the structure of the torus surrounding the Active Galactic Nucleus (AGN)? Is the shape defined or still under speculations? And are there different structures for this torus possible i.e., does it vary from galaxy to galaxy?

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    $\begingroup$ stp30 you've been asking a lot of general questions about AGN recently; it may be best to wait until you have a more specific question in mind. For example, typing 'AGN Torus' in to google gives a number of recent papers and discussions about the range of shapes of torii observed and theorised in the past decade $\endgroup$ Commented May 28, 2014 at 10:22

1 Answer 1


This question was asked more roughly 8 years ago, and for 2 years there is a review article around which I found worth mentioning and summarizing. The manuscript is called Redefining the torus: A unifying view of AGN in the infrared and sub mm and work of Sebastian Florian Hönig. Here an excerpt of the abstract:

The advent of high-angular resolution IR and sub-mm interferometry allows for spatially-resolvedobservations of the parsec-scale environment of active galactic nuclei (AGN), commonly referred toas the “torus.” While molecular lines show the presence of large, massive disks, the IR observationsappear to be dominated by a strong polar component that has been interpreted.

The main result seems to be the following schematic picture (Fig. 4 of the manuscript) of the AGN which is an overlay of various observations:

Fig 4 of arXiv:1909.08639

  1. The purple ring are observations in the near-IR.
  2. The yellow torus and the gray dashed lines are from ${\rm H}_2$ emission.
  3. The main brownish cone is from mid-IR.
  4. The redish wobbly plane with the red (solid) arrows and the purple (dashed) arrows are sub-mm obseravtions (${\rm CO/HCN/HCO^+}$)
  5. Bright green dots on the $x$-axis are ${\rm H_2 O}$ maser emissions.

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