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Resolving the nuclear dust distribution of the Seyfert 2 galaxy NGC 3081

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY Volume: 417 Issue: 1 Pages: L46-L50 DOI: 10.1111/j.1745-3933.2011.01117.x Published: OCT 2011

Authors:
Almeida, CR (Almeida, C. Ramos)1; Sanchez-Portal, M (Sanchez-Portal, M.)2; Garcia, AMP (Perez Garcia, A. M.)3,4; Acosta-Pulido, JA (Acosta-Pulido, J. A.)3,4; Castillo, M (Castillo, M.)2; Ramos, AA (Asensio Ramos, A.)3,4; Gonzalez-Serrano, JI (Gonzalez-Serrano, J. I.)5; Alonso-Herrero, A (Alonso-Herrero, A.)6; Espinosa, JMR (Rodriguez Espinosa, J. M.)3,4; Hatziminaoglou, E (Hatziminaoglou, E.)7; Coia, D (Coia, D.)2; Valtchanov, I (Valtchanov, I.)2; Povic, M (Povic, M.)8; Esquej, P (Esquej, P.)6; Packham, C (Packham, C.)9; Altieri, B (Altieri, B.)2

Abstract:
We report far-infrared (FIR) imaging of the Seyfert 2 galaxy NGC 3081 in the range 70-500 mu m, obtained with an unprecedented angular resolution, using the Herschel Space Observatory instruments PACS and SPIRE. The 11 kpc (similar to 70 arcsec) diameter star-forming ring of the galaxy appears resolved up to 250 mu m. We extracted IR (1.6-500 mu m) nuclear fluxes, that is active nucleus-dominated fluxes, and fitted them with clumpy torus models, which successfully reproduce the FIR emission with small torus sizes. Adding the FIR data to the near- and mid-IR spectral energy distribution (SED) results in a torus radial extent of R(o) = 4(-1)(+2) pc, as well as in a flat radial distribution of the clouds (i.e. the q parameter). At wavelengths beyond 200 mu m, cold dust emission at T = 28 +/- 1K from the circumnuclear star-forming ring of 2.3 kpc (similar to 15 arcsec) in diameter starts making a contribution to the nuclear emission. The dust in the outer parts of the galaxy is heated by the interstellar radiation field (19 +/- 3K).

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