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WISE view of narrow-line Seyfert 1 galaxies: mid-infrared colour and variability

WISE view of narrow-line Seyfert 1 galaxies: mid-infrared colour and variability
WISE view of narrow-line Seyfert 1 galaxies: mid-infrared colour and variability
We present the colour and flux variability analysis at 3.4 μm (W1 band) and 4.6 μm (W2 band) of 492 narrow-line Seyfert 1 (NLSy1) galaxies using archival data from the Wide-field Infrared Survey Explorer (WISE). In the WISE colour-colour, (W1 - W2) versus (W2 - W3) diagram, {˜ } 58{{ per cent}} of the NLSy1 galaxies of our sample lie in the region occupied by the blazar category of active galactic nuclei (AGNs). The mean W1 - W2 colour of candidate variable NLSy1 galaxies is 0.99 ± 0.18 mag. The average amplitude of variability is 0.11 ± 0.07 mag in long term (multiyear) with no difference in variability between W1 and W2 bands. The W1 - W2 colour of NLSy1 galaxies is anticorrelated with the relative strength of [O III] to Hβ, strongly correlated with continuum luminosity, black hole mass, and Eddington ratio. The long-term amplitude of variability shows weak anticorrelation with the Fe II strength, continuum luminosity and Eddington ratio. A positive correlation between colour as well as the amplitude of variability with the radio power at 1.4 GHz was found for the radio-detected NLSy1 galaxies. This suggests non-thermal synchrotron contribution to the mid-infrared colour and flux variability in radio-detected NLSy1 galaxies.
techniques: photometric, galaxies: active, galaxies: Seyfert
0035-8711
2362-2370
Rakshit, Suvendu
6bd5cf6c-ff47-48ab-89fe-68113476ae26
Johnson, Ansu
500fc67e-81c4-4763-8c3b-10b20e49d5f5
Stalin, C. S.
889816b3-bc9a-491a-adb6-c4ba2fe0438b
Gandhi, Poshak
5bc3b5af-42b0-4dd8-8f1f-f74048d4d4a9
Hoenig, Sebastian
be0bb8bc-bdac-4442-8edc-f735834f3917
Rakshit, Suvendu
6bd5cf6c-ff47-48ab-89fe-68113476ae26
Johnson, Ansu
500fc67e-81c4-4763-8c3b-10b20e49d5f5
Stalin, C. S.
889816b3-bc9a-491a-adb6-c4ba2fe0438b
Gandhi, Poshak
5bc3b5af-42b0-4dd8-8f1f-f74048d4d4a9
Hoenig, Sebastian
be0bb8bc-bdac-4442-8edc-f735834f3917

Rakshit, Suvendu, Johnson, Ansu, Stalin, C. S., Gandhi, Poshak and Hoenig, Sebastian (2019) WISE view of narrow-line Seyfert 1 galaxies: mid-infrared colour and variability. Monthly Notices of the Royal Astronomical Society, 483 (2), 2362-2370. (doi:10.1093/mnras/sty3261).

Record type: Article

Abstract

We present the colour and flux variability analysis at 3.4 μm (W1 band) and 4.6 μm (W2 band) of 492 narrow-line Seyfert 1 (NLSy1) galaxies using archival data from the Wide-field Infrared Survey Explorer (WISE). In the WISE colour-colour, (W1 - W2) versus (W2 - W3) diagram, {˜ } 58{{ per cent}} of the NLSy1 galaxies of our sample lie in the region occupied by the blazar category of active galactic nuclei (AGNs). The mean W1 - W2 colour of candidate variable NLSy1 galaxies is 0.99 ± 0.18 mag. The average amplitude of variability is 0.11 ± 0.07 mag in long term (multiyear) with no difference in variability between W1 and W2 bands. The W1 - W2 colour of NLSy1 galaxies is anticorrelated with the relative strength of [O III] to Hβ, strongly correlated with continuum luminosity, black hole mass, and Eddington ratio. The long-term amplitude of variability shows weak anticorrelation with the Fe II strength, continuum luminosity and Eddington ratio. A positive correlation between colour as well as the amplitude of variability with the radio power at 1.4 GHz was found for the radio-detected NLSy1 galaxies. This suggests non-thermal synchrotron contribution to the mid-infrared colour and flux variability in radio-detected NLSy1 galaxies.

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1811.11372 - Accepted Manuscript
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Accepted/In Press date: 27 November 2018
e-pub ahead of print date: 30 November 2018
Published date: 1 February 2019
Keywords: techniques: photometric, galaxies: active, galaxies: Seyfert

Identifiers

Local EPrints ID: 429113
URI: http://eprints.soton.ac.uk/id/eprint/429113
ISSN: 0035-8711
PURE UUID: 4ef6e3e8-76fd-452c-b586-ba182a7d95c7
ORCID for Poshak Gandhi: ORCID iD orcid.org/0000-0003-3105-2615

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Date deposited: 21 Mar 2019 17:30
Last modified: 07 Oct 2020 02:06

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