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The size and structure of the dusty circumnuclear torus in active galacticnuclei (AGN) can be investigated by analyzing the temporal response of thetorus's infrared (IR) dust emission to variations in the AGNultraviolet/optical luminosity. This method, reverberation mapping, isapplicable over a wide redshift range, but the IR response is sensitive toseveral poorly constrained variables relating to the dust distribution and itsillumination, complicating the interpretation of measured reverberation lags.We have used an enhanced version of our torus reverberation mapping code(TORMAC) to conduct a comprehensive exploration of the torus response functionsat selected wavelengths, for the standard interstellar medium graincomposition. The shapes of the response functions vary widely over theparameter range covered by our models, with the largest variations occurring atshorter wavelengths ($\leq 4.5\,\mu$m). The reverberation lag, quantified asthe response-weighted delay (RWD), is most affected by the radial depth of thetorus, the steepness of the radial cloud distribution, the degree of anisotropyof the AGN radiation field, and the volume filling factor. Nevertheless, wefind that the RWD provides a reasonably robust estimate, to within a factor of$\sim 3$, of the luminosity-weighted torus radius, confirming the basicassumption underlying reverberation mapping. However, overall, the modelspredict radii at $2.2\,\mu$m that are a typically factor of $\sim 2$ largerthan those derived from K-band reverberation mapping. This is likely anindication that the innermost region of the torus is populated by cloudsdominated by large graphite grains.

Modeling the Infrared Reverberation Response of the Circumnuclear Dusty Torus in AGNs: An Investigation of Torus Response Functions