Molecular gas in z ∼ 6 quasar host galaxies

Ran Wang, Chris L. Carilli, R. Neri, D. A. Riechers, Jeff Wagg, Fabian Walter, Frank Bertoldi, Karlm Menten, Alain Omont, Pierre Cox, Xiaohui Fan

Research output: Contribution to journalArticle

154 Citations (Scopus)

Abstract

We report our new observations of redshifted carbon monoxide emission from six z ∼ 6 quasars, using the IRAM Plateau de Bure Interferometer. CO (6-5) or (5-4) line emission was detected in all six sources. Together with two other previous CO detections, these observations provide unique constraints on the molecular gas emission properties in these quasar systems close to the end of the cosmic re-ionization. Complementary results are also presented for low-J CO lines observed at the Green Bank Telescope and the Very Large Array, and dust continuum from five of these sources with the SHARC-II bolometer camera at the Caltech Submillimeter Observatory. We then present a study of the molecular gas properties in our combined sample of eight CO-detected quasars at z 6. The detections of high-order CO line emission in these objects indicates the presence of highly excited molecular gas, with estimated masses on the order of 1010 M within the quasar host galaxies. No significant difference is found in the gas mass and CO line width distributions between our z ∼ 6 quasars and samples of CO-detected 1.4 ≤ z ≤ 5 quasars and submillimeter galaxies. Most of the CO-detected quasars at z ∼ 6 follow the far-infrared-CO luminosity relationship defined by actively star-forming galaxies at low and high redshifts. This suggests that ongoing star formation in their hosts contributes significantly to the dust heating at FIR wavelengths. The result is consistent with the picture of galaxy formation co-eval with supermassive black hole (SMBH) accretion in the earliest quasar-host systems. We investigate the black hole-bulge relationships of our quasar sample, using the CO dynamics as a tracer for the dynamical mass of the quasar host. The median estimated black hole-bulge mass ratio is about 15 times higher than the present-day value of 0.0014. This places important constraints on the formation and evolution of the most massive SMBH-spheroidal host systems at the highest redshift.

Original languageEnglish (US)
Pages (from-to)699-712
Number of pages14
JournalAstrophysical Journal
Volume714
Issue number1
DOIs
StatePublished - 2010

Fingerprint

molecular gases
quasars
galaxies
gas
dust
interferometer
carbon monoxide
ionization
observatory
tracer
accretion
plateau
heating
wavelength
Very Large Array (VLA)
bolometers
galactic evolution
mass ratios
tracers
star formation

Keywords

  • Galaxies: active
  • Galaxies: high-redshift
  • Galaxies: starburst
  • Molecular data
  • Radio lines: galaxies

ASJC Scopus subject areas

  • Space and Planetary Science
  • Astronomy and Astrophysics

Cite this

Wang, R., Carilli, C. L., Neri, R., Riechers, D. A., Wagg, J., Walter, F., ... Fan, X. (2010). Molecular gas in z ∼ 6 quasar host galaxies. Astrophysical Journal, 714(1), 699-712. https://doi.org/10.1088/0004-637X/714/1/699

Molecular gas in z ∼ 6 quasar host galaxies. / Wang, Ran; Carilli, Chris L.; Neri, R.; Riechers, D. A.; Wagg, Jeff; Walter, Fabian; Bertoldi, Frank; Menten, Karlm; Omont, Alain; Cox, Pierre; Fan, Xiaohui.

In: Astrophysical Journal, Vol. 714, No. 1, 2010, p. 699-712.

Research output: Contribution to journalArticle

Wang, R, Carilli, CL, Neri, R, Riechers, DA, Wagg, J, Walter, F, Bertoldi, F, Menten, K, Omont, A, Cox, P & Fan, X 2010, 'Molecular gas in z ∼ 6 quasar host galaxies', Astrophysical Journal, vol. 714, no. 1, pp. 699-712. https://doi.org/10.1088/0004-637X/714/1/699
Wang R, Carilli CL, Neri R, Riechers DA, Wagg J, Walter F et al. Molecular gas in z ∼ 6 quasar host galaxies. Astrophysical Journal. 2010;714(1):699-712. https://doi.org/10.1088/0004-637X/714/1/699
Wang, Ran ; Carilli, Chris L. ; Neri, R. ; Riechers, D. A. ; Wagg, Jeff ; Walter, Fabian ; Bertoldi, Frank ; Menten, Karlm ; Omont, Alain ; Cox, Pierre ; Fan, Xiaohui. / Molecular gas in z ∼ 6 quasar host galaxies. In: Astrophysical Journal. 2010 ; Vol. 714, No. 1. pp. 699-712.
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AU - Carilli, Chris L.

AU - Neri, R.

AU - Riechers, D. A.

AU - Wagg, Jeff

AU - Walter, Fabian

AU - Bertoldi, Frank

AU - Menten, Karlm

AU - Omont, Alain

AU - Cox, Pierre

AU - Fan, Xiaohui

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N2 - We report our new observations of redshifted carbon monoxide emission from six z ∼ 6 quasars, using the IRAM Plateau de Bure Interferometer. CO (6-5) or (5-4) line emission was detected in all six sources. Together with two other previous CO detections, these observations provide unique constraints on the molecular gas emission properties in these quasar systems close to the end of the cosmic re-ionization. Complementary results are also presented for low-J CO lines observed at the Green Bank Telescope and the Very Large Array, and dust continuum from five of these sources with the SHARC-II bolometer camera at the Caltech Submillimeter Observatory. We then present a study of the molecular gas properties in our combined sample of eight CO-detected quasars at z 6. The detections of high-order CO line emission in these objects indicates the presence of highly excited molecular gas, with estimated masses on the order of 1010 M ⊙ within the quasar host galaxies. No significant difference is found in the gas mass and CO line width distributions between our z ∼ 6 quasars and samples of CO-detected 1.4 ≤ z ≤ 5 quasars and submillimeter galaxies. Most of the CO-detected quasars at z ∼ 6 follow the far-infrared-CO luminosity relationship defined by actively star-forming galaxies at low and high redshifts. This suggests that ongoing star formation in their hosts contributes significantly to the dust heating at FIR wavelengths. The result is consistent with the picture of galaxy formation co-eval with supermassive black hole (SMBH) accretion in the earliest quasar-host systems. We investigate the black hole-bulge relationships of our quasar sample, using the CO dynamics as a tracer for the dynamical mass of the quasar host. The median estimated black hole-bulge mass ratio is about 15 times higher than the present-day value of 0.0014. This places important constraints on the formation and evolution of the most massive SMBH-spheroidal host systems at the highest redshift.

AB - We report our new observations of redshifted carbon monoxide emission from six z ∼ 6 quasars, using the IRAM Plateau de Bure Interferometer. CO (6-5) or (5-4) line emission was detected in all six sources. Together with two other previous CO detections, these observations provide unique constraints on the molecular gas emission properties in these quasar systems close to the end of the cosmic re-ionization. Complementary results are also presented for low-J CO lines observed at the Green Bank Telescope and the Very Large Array, and dust continuum from five of these sources with the SHARC-II bolometer camera at the Caltech Submillimeter Observatory. We then present a study of the molecular gas properties in our combined sample of eight CO-detected quasars at z 6. The detections of high-order CO line emission in these objects indicates the presence of highly excited molecular gas, with estimated masses on the order of 1010 M ⊙ within the quasar host galaxies. No significant difference is found in the gas mass and CO line width distributions between our z ∼ 6 quasars and samples of CO-detected 1.4 ≤ z ≤ 5 quasars and submillimeter galaxies. Most of the CO-detected quasars at z ∼ 6 follow the far-infrared-CO luminosity relationship defined by actively star-forming galaxies at low and high redshifts. This suggests that ongoing star formation in their hosts contributes significantly to the dust heating at FIR wavelengths. The result is consistent with the picture of galaxy formation co-eval with supermassive black hole (SMBH) accretion in the earliest quasar-host systems. We investigate the black hole-bulge relationships of our quasar sample, using the CO dynamics as a tracer for the dynamical mass of the quasar host. The median estimated black hole-bulge mass ratio is about 15 times higher than the present-day value of 0.0014. This places important constraints on the formation and evolution of the most massive SMBH-spheroidal host systems at the highest redshift.

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KW - Galaxies: high-redshift

KW - Galaxies: starburst

KW - Molecular data

KW - Radio lines: galaxies

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