The University of Southampton
University of Southampton Institutional Repository

A candidate optically quiescent quasar lacking narrow emission lines

A candidate optically quiescent quasar lacking narrow emission lines
A candidate optically quiescent quasar lacking narrow emission lines
Many active galactic nuclei (AGN) surveys rely on optical emission line signatures for robust source classification. There are, however, examples of luminous AGN candidates lacking such signatures, including those from the narrow-line region, which are expected to be less susceptible to classical nuclear (torus) obscuration. Here, we seek to formalize this subpopulation of AGN with a prototypical candidate, SDSS J075139.06+402810.9. This shows infrared (IR) colours typical for AGN, an optical spectrum dominated by an early type galaxy continuum, an [O III] λ5007Å limiting flux about two dex below Type 2 quasars at similar IR power, and a k-corrected 12 μm quasar-like luminosity of ∼ 1045 erg s−1. These characteristics are not consistent with jet and host galaxy dilution. A potential scenario to explain this AGN quiescence in the optical is a sky-covering ‘cocoon’ of obscuring material, such that the AGN ionizing radiation is unable to escape and excite gas on kpc scales. Alternatively, we may be witnessing the short phase between recent triggering of obscured AGN activity and the subsequent narrow-line excitation. This prototype could define the base properties of an emerging candidate AGN subtype – an intriguing transitional phase in AGN and galaxy evolution.
1745-3925
L80–L84
Greenwell, Claire
34ce34ea-9a03-44c4-801f-9aa1e6c2961d
Gandhi, Poshak
5bc3b5af-42b0-4dd8-8f1f-f74048d4d4a9
Stern, Daniel
310a8ace-0df3-45d7-86f9-febc5e075a84
Boorman, Peter
10d631e5-8046-43fe-9192-258bb1e28c42
Toba, Yoshiki
e2cbc0e8-772e-4360-979e-6f634a9667b1
Lansbury, George
c07a0ab1-523c-4284-b2b9-5c9afc94b717
Mainieri, Vincenzo
494b6749-7340-474f-ae98-0c40e9d13854
Desira, Christopher
0e0c81a4-a041-4de9-9706-7d0344036d2b
Greenwell, Claire
34ce34ea-9a03-44c4-801f-9aa1e6c2961d
Gandhi, Poshak
5bc3b5af-42b0-4dd8-8f1f-f74048d4d4a9
Stern, Daniel
310a8ace-0df3-45d7-86f9-febc5e075a84
Boorman, Peter
10d631e5-8046-43fe-9192-258bb1e28c42
Toba, Yoshiki
e2cbc0e8-772e-4360-979e-6f634a9667b1
Lansbury, George
c07a0ab1-523c-4284-b2b9-5c9afc94b717
Mainieri, Vincenzo
494b6749-7340-474f-ae98-0c40e9d13854
Desira, Christopher
0e0c81a4-a041-4de9-9706-7d0344036d2b

Greenwell, Claire, Gandhi, Poshak, Stern, Daniel, Boorman, Peter, Toba, Yoshiki, Lansbury, George, Mainieri, Vincenzo and Desira, Christopher (2021) A candidate optically quiescent quasar lacking narrow emission lines. Monthly Notices of the Royal Astronomical Society: Letters, 503 (1), L80–L84. (doi:10.1093/mnrasl/slab019).

Record type: Article

Abstract

Many active galactic nuclei (AGN) surveys rely on optical emission line signatures for robust source classification. There are, however, examples of luminous AGN candidates lacking such signatures, including those from the narrow-line region, which are expected to be less susceptible to classical nuclear (torus) obscuration. Here, we seek to formalize this subpopulation of AGN with a prototypical candidate, SDSS J075139.06+402810.9. This shows infrared (IR) colours typical for AGN, an optical spectrum dominated by an early type galaxy continuum, an [O III] λ5007Å limiting flux about two dex below Type 2 quasars at similar IR power, and a k-corrected 12 μm quasar-like luminosity of ∼ 1045 erg s−1. These characteristics are not consistent with jet and host galaxy dilution. A potential scenario to explain this AGN quiescence in the optical is a sky-covering ‘cocoon’ of obscuring material, such that the AGN ionizing radiation is unable to escape and excite gas on kpc scales. Alternatively, we may be witnessing the short phase between recent triggering of obscured AGN activity and the subsequent narrow-line excitation. This prototype could define the base properties of an emerging candidate AGN subtype – an intriguing transitional phase in AGN and galaxy evolution.

Text
A candidate optically quiescent quasar lacking narrow emission lines - Accepted Manuscript
Download (754kB)

More information

Accepted/In Press date: 19 February 2021
e-pub ahead of print date: 26 February 2021
Additional Information: arxiv is am

Identifiers

Local EPrints ID: 449646
URI: http://eprints.soton.ac.uk/id/eprint/449646
ISSN: 1745-3925
PURE UUID: f0d5929a-70b7-46cd-a827-92f039c0743d
ORCID for Poshak Gandhi: ORCID iD orcid.org/0000-0003-3105-2615

Catalogue record

Date deposited: 10 Jun 2021 16:30
Last modified: 11 Jun 2021 01:45

Export record

Altmetrics

Contributors

Author: Claire Greenwell
Author: Poshak Gandhi ORCID iD
Author: Daniel Stern
Author: Peter Boorman
Author: Yoshiki Toba
Author: George Lansbury
Author: Vincenzo Mainieri
Author: Christopher Desira

University divisions

Download statistics

Downloads from ePrints over the past year. Other digital versions may also be available to download e.g. from the publisher's website.

View more statistics

Atom RSS 1.0 RSS 2.0

Contact ePrints Soton: eprints@soton.ac.uk

ePrints Soton supports OAI 2.0 with a base URL of http://eprints.soton.ac.uk/cgi/oai2

This repository has been built using EPrints software, developed at the University of Southampton, but available to everyone to use.

We use cookies to ensure that we give you the best experience on our website. If you continue without changing your settings, we will assume that you are happy to receive cookies on the University of Southampton website.

×