The Intrinsic Far-infrared Continua of Type-1 Quasars

Jianwei Lyu, George H. Rieke

Research output: Contribution to journalArticle

16 Citations (Scopus)

Abstract

The range of currently proposed active galactic nucleus (AGN) far-infrared templates results in uncertainties in retrieving host galaxy information from infrared observations and also undermines constraints on the outer part of the AGN torus. We discuss how to test and reconcile these templates. Physically, the fraction of the intrinsic AGN IR-processed luminosity compared with that from the central engine should be consistent with the dust-covering factor. In addition, besides reproducing the composite spectral energy distributions (SEDs) of quasars, a correct AGN IR template combined with an accurate library of star-forming galaxy templates should be able to reproduce the IR properties of the host galaxies, such as the luminosity-dependent SED shapes and aromatic feature strengths. We develop tests based on these expected behaviors and find that the shape of the AGN intrinsic far-IR emission drops off rapidly starting at ∼20 μm and can be matched by an Elvis et al.-like template with a minor modification. Despite the variations in the near-to mid-IR bands, AGNs in quasars and Seyfert galaxies have remarkably similar intrinsic far-IR SEDs at λ ∼ 20-100 μm, suggesting a similar emission character of the outermost region of the circumnuclear torus. The variations of the intrinsic AGN IR SEDs among the type-1 quasar population can be explained by the changing relative strengths of four major dust components with similar characteristic temperatures, and there is evidence for compact AGN-heated dusty structures at sub-kiloparsec scales in the far-IR.

Original languageEnglish (US)
Article number76
JournalAstrophysical Journal
Volume841
Issue number2
DOIs
StatePublished - Jun 1 2017

Fingerprint

active galactic nuclei
quasars
continuums
spectral energy distribution
templates
energy
galaxies
dust
luminosity
engine
Seyfert galaxies
distribution
engines
coverings
temperature
stars
composite materials
test

Keywords

  • galaxies: active
  • infrared: galaxies
  • quasars: general

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

The Intrinsic Far-infrared Continua of Type-1 Quasars. / Lyu, Jianwei; Rieke, George H.

In: Astrophysical Journal, Vol. 841, No. 2, 76, 01.06.2017.

Research output: Contribution to journalArticle

@article{e78301a53ae64cd6b82548d6718e7b7e,
title = "The Intrinsic Far-infrared Continua of Type-1 Quasars",
abstract = "The range of currently proposed active galactic nucleus (AGN) far-infrared templates results in uncertainties in retrieving host galaxy information from infrared observations and also undermines constraints on the outer part of the AGN torus. We discuss how to test and reconcile these templates. Physically, the fraction of the intrinsic AGN IR-processed luminosity compared with that from the central engine should be consistent with the dust-covering factor. In addition, besides reproducing the composite spectral energy distributions (SEDs) of quasars, a correct AGN IR template combined with an accurate library of star-forming galaxy templates should be able to reproduce the IR properties of the host galaxies, such as the luminosity-dependent SED shapes and aromatic feature strengths. We develop tests based on these expected behaviors and find that the shape of the AGN intrinsic far-IR emission drops off rapidly starting at ∼20 μm and can be matched by an Elvis et al.-like template with a minor modification. Despite the variations in the near-to mid-IR bands, AGNs in quasars and Seyfert galaxies have remarkably similar intrinsic far-IR SEDs at λ ∼ 20-100 μm, suggesting a similar emission character of the outermost region of the circumnuclear torus. The variations of the intrinsic AGN IR SEDs among the type-1 quasar population can be explained by the changing relative strengths of four major dust components with similar characteristic temperatures, and there is evidence for compact AGN-heated dusty structures at sub-kiloparsec scales in the far-IR.",
keywords = "galaxies: active, infrared: galaxies, quasars: general",
author = "Jianwei Lyu and Rieke, {George H.}",
year = "2017",
month = "6",
day = "1",
doi = "10.3847/1538-4357/aa7051",
language = "English (US)",
volume = "841",
journal = "Astrophysical Journal",
issn = "0004-637X",
publisher = "IOP Publishing Ltd.",
number = "2",

}

TY - JOUR

T1 - The Intrinsic Far-infrared Continua of Type-1 Quasars

AU - Lyu, Jianwei

AU - Rieke, George H.

PY - 2017/6/1

Y1 - 2017/6/1

N2 - The range of currently proposed active galactic nucleus (AGN) far-infrared templates results in uncertainties in retrieving host galaxy information from infrared observations and also undermines constraints on the outer part of the AGN torus. We discuss how to test and reconcile these templates. Physically, the fraction of the intrinsic AGN IR-processed luminosity compared with that from the central engine should be consistent with the dust-covering factor. In addition, besides reproducing the composite spectral energy distributions (SEDs) of quasars, a correct AGN IR template combined with an accurate library of star-forming galaxy templates should be able to reproduce the IR properties of the host galaxies, such as the luminosity-dependent SED shapes and aromatic feature strengths. We develop tests based on these expected behaviors and find that the shape of the AGN intrinsic far-IR emission drops off rapidly starting at ∼20 μm and can be matched by an Elvis et al.-like template with a minor modification. Despite the variations in the near-to mid-IR bands, AGNs in quasars and Seyfert galaxies have remarkably similar intrinsic far-IR SEDs at λ ∼ 20-100 μm, suggesting a similar emission character of the outermost region of the circumnuclear torus. The variations of the intrinsic AGN IR SEDs among the type-1 quasar population can be explained by the changing relative strengths of four major dust components with similar characteristic temperatures, and there is evidence for compact AGN-heated dusty structures at sub-kiloparsec scales in the far-IR.

AB - The range of currently proposed active galactic nucleus (AGN) far-infrared templates results in uncertainties in retrieving host galaxy information from infrared observations and also undermines constraints on the outer part of the AGN torus. We discuss how to test and reconcile these templates. Physically, the fraction of the intrinsic AGN IR-processed luminosity compared with that from the central engine should be consistent with the dust-covering factor. In addition, besides reproducing the composite spectral energy distributions (SEDs) of quasars, a correct AGN IR template combined with an accurate library of star-forming galaxy templates should be able to reproduce the IR properties of the host galaxies, such as the luminosity-dependent SED shapes and aromatic feature strengths. We develop tests based on these expected behaviors and find that the shape of the AGN intrinsic far-IR emission drops off rapidly starting at ∼20 μm and can be matched by an Elvis et al.-like template with a minor modification. Despite the variations in the near-to mid-IR bands, AGNs in quasars and Seyfert galaxies have remarkably similar intrinsic far-IR SEDs at λ ∼ 20-100 μm, suggesting a similar emission character of the outermost region of the circumnuclear torus. The variations of the intrinsic AGN IR SEDs among the type-1 quasar population can be explained by the changing relative strengths of four major dust components with similar characteristic temperatures, and there is evidence for compact AGN-heated dusty structures at sub-kiloparsec scales in the far-IR.

KW - galaxies: active

KW - infrared: galaxies

KW - quasars: general

UR - http://www.scopus.com/inward/record.url?scp=85020693640&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85020693640&partnerID=8YFLogxK

U2 - 10.3847/1538-4357/aa7051

DO - 10.3847/1538-4357/aa7051

M3 - Article

AN - SCOPUS:85020693640

VL - 841

JO - Astrophysical Journal

JF - Astrophysical Journal

SN - 0004-637X

IS - 2

M1 - 76

ER -