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The subarcsecond mid-infrared view of local active galactic nuclei.III. Polar dust emission

The subarcsecond mid-infrared view of local active galactic nuclei.III. Polar dust emission
The subarcsecond mid-infrared view of local active galactic nuclei.III. Polar dust emission
Recent mid-infrared (MIR) interferometric observations have shown that in a few active galactic nuclei (AGNs) the bulk of the infrared emission originates from the polar region above the putative torus, where only a little dust should be present. Here, we investigate whether such strong polar dust emission is common in AGNs. Out of 149 Seyferts in the MIR atlas of local AGNs, 21 show extended MIR emission on single-dish images. In 18 objects, the extended MIR emission aligns with the position angle (PA) of the system axis, established by [O iii], radio, polarization, and maser-based PA measurements. The relative amount of resolved MIR emission is at least 40% and scales with the [O iv] fluxes, implying a strong connection between the extended continuum and [O iv] emitters. These results together with the radio-quiet nature of the Seyferts support the scenario that the bulk of MIR emission is emitted by dust in the polar region and not by the torus, which would demand a new paradigm for the infrared emission structure in AGNs. The current low detection rate of polar dust in the AGNs of the MIR atlas is explained by the lack of sufficient high-quality MIR data and the requirements on the orientation, strength of narrow-line region, and distance of the AGNs. The James Webb Space Telescope will enable much deeper nuclear MIR studies with comparable angular resolution, allowing us to resolve the polar emission and surroundings in most of the nearby AGNs
1538-4357
1-13
Asmus, D.
ade84ff0-4867-4f85-b317-6db72e71ccc1
Hoenig, Sebastian
be0bb8bc-bdac-4442-8edc-f735834f3917
Gandhi, Poshak
5bc3b5af-42b0-4dd8-8f1f-f74048d4d4a9
Asmus, D.
ade84ff0-4867-4f85-b317-6db72e71ccc1
Hoenig, Sebastian
be0bb8bc-bdac-4442-8edc-f735834f3917
Gandhi, Poshak
5bc3b5af-42b0-4dd8-8f1f-f74048d4d4a9

Asmus, D., Hoenig, Sebastian and Gandhi, Poshak (2016) The subarcsecond mid-infrared view of local active galactic nuclei.III. Polar dust emission. The Astrophysical Journal, 822 (2), 1-13. (doi:10.3847/0004-637X/822/2/109).

Record type: Article

Abstract

Recent mid-infrared (MIR) interferometric observations have shown that in a few active galactic nuclei (AGNs) the bulk of the infrared emission originates from the polar region above the putative torus, where only a little dust should be present. Here, we investigate whether such strong polar dust emission is common in AGNs. Out of 149 Seyferts in the MIR atlas of local AGNs, 21 show extended MIR emission on single-dish images. In 18 objects, the extended MIR emission aligns with the position angle (PA) of the system axis, established by [O iii], radio, polarization, and maser-based PA measurements. The relative amount of resolved MIR emission is at least 40% and scales with the [O iv] fluxes, implying a strong connection between the extended continuum and [O iv] emitters. These results together with the radio-quiet nature of the Seyferts support the scenario that the bulk of MIR emission is emitted by dust in the polar region and not by the torus, which would demand a new paradigm for the infrared emission structure in AGNs. The current low detection rate of polar dust in the AGNs of the MIR atlas is explained by the lack of sufficient high-quality MIR data and the requirements on the orientation, strength of narrow-line region, and distance of the AGNs. The James Webb Space Telescope will enable much deeper nuclear MIR studies with comparable angular resolution, allowing us to resolve the polar emission and surroundings in most of the nearby AGNs

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Accepted/In Press date: 7 March 2016
e-pub ahead of print date: 12 May 2016
Published date: 12 May 2016
Organisations: Astronomy Group

Identifiers

Local EPrints ID: 396269
URI: https://eprints.soton.ac.uk/id/eprint/396269
ISSN: 1538-4357
PURE UUID: 02fa0fe2-3000-4569-a0ef-59a3495323a3
ORCID for Poshak Gandhi: ORCID iD orcid.org/0000-0003-3105-2615

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Date deposited: 02 Jun 2016 13:22
Last modified: 06 Jun 2018 12:21

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