The nuclear and integrated far-infrared emission of nearby Seyfert galaxies

We present far-infrared (FIR) 70-500 μm imaging observations obtained with Herschel/Photodetector Array Camera (PACS) and Spectral and Photometric Imaging REceiver (SPIRE) of 33 nearby (median distance of 30 Mpc) Seyfert galaxies from the Revised Shapley–Ames (RSA) catalogue. We obtain the FIR nucle...

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Bibliographic Details
Published in:Monthly notices of the Royal Astronomical Society 2016-06, Vol.458 (4), p.4512-4529
Main Authors: García-González, J., Alonso-Herrero, A., Hernán-Caballero, A., Pereira-Santaella, M., Ramos-Almeida, C., Acosta-Pulido, J. A., Díaz-Santos, T., Esquej, P., González-Martín, O., Ichikawa, K., López-Rodríguez, E., Povic, M., Roche, P. F., Sánchez-Portal, M.
Format: Article
Language:English
Subjects:
Astronomy
Cosmic dust
Emission
Estimates
Far infrared radiation
Galaxies
Imaging
Infrared radiation
Photometry
Seyfert galaxies
Star & galaxy formation
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Summary:We present far-infrared (FIR) 70-500 μm imaging observations obtained with Herschel/Photodetector Array Camera (PACS) and Spectral and Photometric Imaging REceiver (SPIRE) of 33 nearby (median distance of 30 Mpc) Seyfert galaxies from the Revised Shapley–Ames (RSA) catalogue. We obtain the FIR nuclear (r = 1 kpc and r = 2 kpc) and integrated spectral energy distributions (SEDs). We estimate the unresolved nuclear emission at 70 μm and we fit the nuclear and integrated FIR SEDs with a grey body model. We find that the integrated FIR emission of the RSA Seyferts in our sample is dominated by emission from the host galaxy, with dust properties similar to those of normal galaxies (non-AGN). We use four criteria to select galaxies whose nuclear 70 μm emission has a significant AGN contribution: (1) elevated 70/160 μm flux ratios, (2) spatially resolved, high dust temperature gradient, (3) 70 μm excess emission with respect to the fit of the FIR SEDs with a grey body, and (4) excess of nuclear SFR obtained from 70 μm over SFR from mid-infrared indicators. 16 galaxies (48 per cent of the initial sample) satisfy at least one of these conditions, whereas 10 satisfy half or more. After careful examination of these, we select six bona fide candidates (18 per cent of the initial sample) and estimate that ∼40–70 per cent of their nuclear (r = 1–2 kpc) 70 μm emission is contributed by dust heated by the AGN.
ISSN:0035-8711
1365-2966
DOI:10.1093/mnras/stw626