High spatial resolution of the mid-infrared emission of the Compton-thick type 2 Seyfert galaxy, Markarian 3
Abstract
The mid-infrared (MIR) spectra observed with Gemini/Michelle have been used to study the nuclear region of the Compton-thick type 2 Seyfert galaxy, Markarian 3 (Mrk 3), at a spatial resolution of ∼200 pc. No polycyclic aromatic hydrocarbon emission bands were detected in the N-band spectrum of Mrk 3. However, intense [Ar III] 8.99 μm, [S IV] 10.5 μm and [Ne II] 12.8 μm ionic emission lines, as well as a silicate absorption feature at 9.7 μm, have been found in the nuclear extraction (∼200 pc). We also present a subarcsecond-resolution Michelle N-band image of Mrk 3, which resolves its circumnuclear region. This diffuse MIR emission shows up as a wing towards the east-west direction, closely aligned with the S-shape of the narrow-line region observed in the optical [O III] λ5007Å image from the Faint Object Camera onboard the Hubble Space Telescope. The nuclear continuum spectrum can be well represented by a theoretical torus spectral energy distribution, suggesting that the nucleus of Mrk 3 might host a dusty toroidal structure, as predicted by the unified model of an active galactic nucleus (AGN). In addition, the hydrogen column density (N_H= 4.8^{+3.3}_{-3.1}× 10^{23} cm-2) estimated with a torus model for Mrk 3 is consistent with the value derived from X-ray spectroscopy. The torus model geometry of Mrk 3 is similar to that of NGC 3281 (both are Compton-thick galaxies), confirmed through fitting the 9.7-μm silicate band profile. These results might provide further evidence that silicate-rich dust can be associated with the AGN torus and might also be responsible for the absorption observed at X-ray wavelengths in those galaxies.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- June 2014
- DOI:
- 10.1093/mnras/stu468
- arXiv:
- arXiv:1403.2266
- Bibcode:
- 2014MNRAS.441..630S
- Keywords:
-
- techniques: spectroscopic;
- dust;
- extinction;
- ISM: molecules;
- galaxies: individual: Markarian 3;
- galaxies: Seyfert;
- infrared: ISM;
- Astrophysics - Galaxy Astrophysics
- E-Print:
- 11 pages, 6 figures