Spitzer quasar and ulirg evolution study (quest). I. The origin of the far-infrared continuum of QSOs

M. Schweitzer, D. Lutz, E. Sturm, A. Contursi, L. J. Tacconi, M. D. Lehnert, K. M. Dasyra, R. Genzel, S. Veilleux, D. Rupke, D. C. Kim, Andrew Baker, H. Netzer, A. Sternberg, J. Mazzarella, S. Lord

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Abstract

This paper addresses the origin of the far-infrared (FIR) continuum of QSOs, based on the Quasar and ULIRG Evolution Study (QUEST) of nearby QSOs and ULIRGs using observations with the Spitzer Space Telescope. For 27 Palomar-Green QSOs at z ≲ 0.3, we derive luminosities of diagnostic lines ([Ne II] 12.8 μm, [Ne V] 14.3 μm, [O IV] 25.9 μm) and emission features (PAH 7.7 μm emission, which is related to star formation), as well as continuum luminosities over a range of mid- to far-infrared wavelengths between 6 and 60 μm. We detect star-formation-related PAH emission in 11/26 QSOs and fine-structure line emission in all of them, often in multiple lines. The detection of PAHs in the average spectrum of sources that lack individual PAH detections provides further evidence for the widespread presence of PAHs in QSOs. Similar PAH/FIR and [Ne II]/FIR ratios are found in QSOs and in starburst-dominated ULIRGs and lower luminosity starbursts. We conclude that the typical QSO in our sample has at least 30% but likely most of the far-infrared luminosity (∼1010-1012L) arising from star formation, with a tendency for larger star formation contribution at the largest FIR luminosities. In the QSO sample, we find correlations between most of the quantities studied including combinations of AGN tracers and starburst tracers. The common scaling of AGN and starburst luminosities (and fluxes) is evidence for a starburst-AGN connection in luminous AGN. Strong correlations of far-infrared continuum and starburst related quantities (PAH, low-excitation [Ne II]) offer additional support for the starburst origin of far-infrared emission.

Original languageEnglish (US)
Pages (from-to)79-90
Number of pages12
JournalAstrophysical Journal
Volume649
Issue number1 I
DOIs
StatePublished - Sep 20 2006

Fingerprint

quasars
polycyclic aromatic hydrocarbons
PAH
continuums
luminosity
star formation
tracer
tracers
Space Infrared Telescope Facility
wavelength
tendencies
fine structure
scaling
wavelengths
excitation

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

Keywords

  • Galaxies: active
  • Galaxies: starburst
  • Infrared: galaxies
  • Quasars: emission lines

Cite this

Schweitzer, M., Lutz, D., Sturm, E., Contursi, A., Tacconi, L. J., Lehnert, M. D., ... Lord, S. (2006). Spitzer quasar and ulirg evolution study (quest). I. The origin of the far-infrared continuum of QSOs. Astrophysical Journal, 649(1 I), 79-90. https://doi.org/10.1086/506510
Schweitzer, M. ; Lutz, D. ; Sturm, E. ; Contursi, A. ; Tacconi, L. J. ; Lehnert, M. D. ; Dasyra, K. M. ; Genzel, R. ; Veilleux, S. ; Rupke, D. ; Kim, D. C. ; Baker, Andrew ; Netzer, H. ; Sternberg, A. ; Mazzarella, J. ; Lord, S. / Spitzer quasar and ulirg evolution study (quest). I. The origin of the far-infrared continuum of QSOs. In: Astrophysical Journal. 2006 ; Vol. 649, No. 1 I. pp. 79-90.
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abstract = "This paper addresses the origin of the far-infrared (FIR) continuum of QSOs, based on the Quasar and ULIRG Evolution Study (QUEST) of nearby QSOs and ULIRGs using observations with the Spitzer Space Telescope. For 27 Palomar-Green QSOs at z ≲ 0.3, we derive luminosities of diagnostic lines ([Ne II] 12.8 μm, [Ne V] 14.3 μm, [O IV] 25.9 μm) and emission features (PAH 7.7 μm emission, which is related to star formation), as well as continuum luminosities over a range of mid- to far-infrared wavelengths between 6 and 60 μm. We detect star-formation-related PAH emission in 11/26 QSOs and fine-structure line emission in all of them, often in multiple lines. The detection of PAHs in the average spectrum of sources that lack individual PAH detections provides further evidence for the widespread presence of PAHs in QSOs. Similar PAH/FIR and [Ne II]/FIR ratios are found in QSOs and in starburst-dominated ULIRGs and lower luminosity starbursts. We conclude that the typical QSO in our sample has at least 30{\%} but likely most of the far-infrared luminosity (∼1010-1012L⊙) arising from star formation, with a tendency for larger star formation contribution at the largest FIR luminosities. In the QSO sample, we find correlations between most of the quantities studied including combinations of AGN tracers and starburst tracers. The common scaling of AGN and starburst luminosities (and fluxes) is evidence for a starburst-AGN connection in luminous AGN. Strong correlations of far-infrared continuum and starburst related quantities (PAH, low-excitation [Ne II]) offer additional support for the starburst origin of far-infrared emission.",
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Schweitzer, M, Lutz, D, Sturm, E, Contursi, A, Tacconi, LJ, Lehnert, MD, Dasyra, KM, Genzel, R, Veilleux, S, Rupke, D, Kim, DC, Baker, A, Netzer, H, Sternberg, A, Mazzarella, J & Lord, S 2006, 'Spitzer quasar and ulirg evolution study (quest). I. The origin of the far-infrared continuum of QSOs', Astrophysical Journal, vol. 649, no. 1 I, pp. 79-90. https://doi.org/10.1086/506510

Spitzer quasar and ulirg evolution study (quest). I. The origin of the far-infrared continuum of QSOs. / Schweitzer, M.; Lutz, D.; Sturm, E.; Contursi, A.; Tacconi, L. J.; Lehnert, M. D.; Dasyra, K. M.; Genzel, R.; Veilleux, S.; Rupke, D.; Kim, D. C.; Baker, Andrew; Netzer, H.; Sternberg, A.; Mazzarella, J.; Lord, S.

In: Astrophysical Journal, Vol. 649, No. 1 I, 20.09.2006, p. 79-90.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Spitzer quasar and ulirg evolution study (quest). I. The origin of the far-infrared continuum of QSOs

AU - Schweitzer, M.

AU - Lutz, D.

AU - Sturm, E.

AU - Contursi, A.

AU - Tacconi, L. J.

AU - Lehnert, M. D.

AU - Dasyra, K. M.

AU - Genzel, R.

AU - Veilleux, S.

AU - Rupke, D.

AU - Kim, D. C.

AU - Baker, Andrew

AU - Netzer, H.

AU - Sternberg, A.

AU - Mazzarella, J.

AU - Lord, S.

PY - 2006/9/20

Y1 - 2006/9/20

N2 - This paper addresses the origin of the far-infrared (FIR) continuum of QSOs, based on the Quasar and ULIRG Evolution Study (QUEST) of nearby QSOs and ULIRGs using observations with the Spitzer Space Telescope. For 27 Palomar-Green QSOs at z ≲ 0.3, we derive luminosities of diagnostic lines ([Ne II] 12.8 μm, [Ne V] 14.3 μm, [O IV] 25.9 μm) and emission features (PAH 7.7 μm emission, which is related to star formation), as well as continuum luminosities over a range of mid- to far-infrared wavelengths between 6 and 60 μm. We detect star-formation-related PAH emission in 11/26 QSOs and fine-structure line emission in all of them, often in multiple lines. The detection of PAHs in the average spectrum of sources that lack individual PAH detections provides further evidence for the widespread presence of PAHs in QSOs. Similar PAH/FIR and [Ne II]/FIR ratios are found in QSOs and in starburst-dominated ULIRGs and lower luminosity starbursts. We conclude that the typical QSO in our sample has at least 30% but likely most of the far-infrared luminosity (∼1010-1012L⊙) arising from star formation, with a tendency for larger star formation contribution at the largest FIR luminosities. In the QSO sample, we find correlations between most of the quantities studied including combinations of AGN tracers and starburst tracers. The common scaling of AGN and starburst luminosities (and fluxes) is evidence for a starburst-AGN connection in luminous AGN. Strong correlations of far-infrared continuum and starburst related quantities (PAH, low-excitation [Ne II]) offer additional support for the starburst origin of far-infrared emission.

AB - This paper addresses the origin of the far-infrared (FIR) continuum of QSOs, based on the Quasar and ULIRG Evolution Study (QUEST) of nearby QSOs and ULIRGs using observations with the Spitzer Space Telescope. For 27 Palomar-Green QSOs at z ≲ 0.3, we derive luminosities of diagnostic lines ([Ne II] 12.8 μm, [Ne V] 14.3 μm, [O IV] 25.9 μm) and emission features (PAH 7.7 μm emission, which is related to star formation), as well as continuum luminosities over a range of mid- to far-infrared wavelengths between 6 and 60 μm. We detect star-formation-related PAH emission in 11/26 QSOs and fine-structure line emission in all of them, often in multiple lines. The detection of PAHs in the average spectrum of sources that lack individual PAH detections provides further evidence for the widespread presence of PAHs in QSOs. Similar PAH/FIR and [Ne II]/FIR ratios are found in QSOs and in starburst-dominated ULIRGs and lower luminosity starbursts. We conclude that the typical QSO in our sample has at least 30% but likely most of the far-infrared luminosity (∼1010-1012L⊙) arising from star formation, with a tendency for larger star formation contribution at the largest FIR luminosities. In the QSO sample, we find correlations between most of the quantities studied including combinations of AGN tracers and starburst tracers. The common scaling of AGN and starburst luminosities (and fluxes) is evidence for a starburst-AGN connection in luminous AGN. Strong correlations of far-infrared continuum and starburst related quantities (PAH, low-excitation [Ne II]) offer additional support for the starburst origin of far-infrared emission.

KW - Galaxies: active

KW - Galaxies: starburst

KW - Infrared: galaxies

KW - Quasars: emission lines

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Schweitzer M, Lutz D, Sturm E, Contursi A, Tacconi LJ, Lehnert MD et al. Spitzer quasar and ulirg evolution study (quest). I. The origin of the far-infrared continuum of QSOs. Astrophysical Journal. 2006 Sep 20;649(1 I):79-90. https://doi.org/10.1086/506510