Molecular gas in the host galaxy of a quasar at redshift z = 6.42


Observations of molecular hydrogen in quasar host galaxies at high redshifts provide fundamental constraints on galaxy evolution, because it is out of this molecular gas that stars form. Molecular hydrogen is traced by emission from the carbon monoxide molecule, CO; cold H2 itself is generally not observable. Carbon monoxide has been detected in about ten quasar host galaxies with redshifts z > 2; the record-holder is at z = 4.69 (refs 1–3). Here we report CO emission from the quasar SDSS J114816.64 + 525150.3 (refs 5, 6) at z = 6.42. At that redshift, the Universe was only 1/16 of its present age, and the era of cosmic reionization was just ending. The presence of about 2 × 1010M of H2 in an object at this time demonstrates that molecular gas enriched with heavy elements can be generated rapidly in the youngest galaxies.

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Figure 1: CO detection in J1148 + 5251.
Figure 2: The CO spectrum of J1148 + 5251.


  1. 1

    Ohta, K. et al. Detection of molecular gas in the quasar BR1202-0725 at redshift z = 4.69. Nature 382, 426–428 (1996)

    ADS  CAS  Article  Google Scholar 

  2. 2

    Omont, A. et al. Molecular gas and dust around a radio-quiet quasar at redshift 4.69. Nature 382, 428–431 (1996)

    ADS  CAS  Article  Google Scholar 

  3. 3

    Carilli, C. L. et al. High-resolution imaging of molecular line emission from high redshift QSOs. Astron. J 123, 1838–1846 (2002)

    ADS  CAS  Article  Google Scholar 

  4. 4

    Carilli, C. L. & Blain, A. W. Centimeter searches for molecular line emission from high-redshift galaxies. Astrophys. J. 569, 605–610 (2002)

    ADS  CAS  Article  Google Scholar 

  5. 5

    Fan, X. et al. A survey of z > 5.7 quasars in the sloan digital sky survey. II. Discovery of three additional quasars at z > 6. Astron. J. 125, 1649–1659 (2003)

    ADS  Article  Google Scholar 

  6. 6

    White, R. L., Becker, R. H., Fan, X. & Strauss, M. A. Probing the ionization state of the universe at z > 6. Astron. J. (in the press)

  7. 7

    Willott, C. J., McLure, R. L. & Jarvis, M. J. A 3 × 109 M black hole in the quasar SDSS J1148 + 5251 at z = 6.41. Astrophys. J. 587, L15–L18 (2003)

    ADS  Article  Google Scholar 

  8. 8

    Loeb, A. & Barkana, R. The reionization of the Universe by the first stars and quasars. Annu. Rev. Astron. Astrophys. 39, 19–66 (2000)

    ADS  Article  Google Scholar 

  9. 9

    Bertoldi, F. et al. Dust emission from the most distant quasars. Astron. Astrophys. Lett. (in the press)

  10. 10

    Bertoldi, F. et al. Molecular gas in the host galaxy of a quasar at redshift z = 6.42. Astron. Astrophys. (in the press)

  11. 11

    Solomon, P. M., Radford, S. J. E. & Downes, D. Molecular gas content of the primeval galaxy IRAS 10214 + 4724. Nature 356, 318–321 (1992)

    ADS  CAS  Article  Google Scholar 

  12. 12

    Strong, A. W. et al. Diffuse continuum gamma rays from the Galaxy observed by COMPTEL. Astron. Astrophys. 292, 82–91 (1994)

    ADS  Google Scholar 

  13. 13

    Downes, D. & Solomon, P. Rotating nuclear rings and extreme starbursts in ultra-luminous galaxies. Astrophys. J. 507, 615–654 (1998)

    ADS  CAS  Article  Google Scholar 

  14. 14

    Weiss, A., Neininger, N., Huttemeister, S. & Klein, U. The effect of violent star formation on the state of the molecular gas in M82. Astron. Astrophys. 365, 571–587 (2001)

    ADS  Article  Google Scholar 

  15. 15

    Solomon, P. M., Downes, D., Radford, S. J. E. & Barrett, J. W. The molecular inter-stellar medium in ultraluminous infrared galaxies. Astrophys. J. 478, 144 (1997)

    ADS  CAS  Article  Google Scholar 

  16. 16

    Ferrarese, L. & Merritt, D. A fundamental relation between supermassive black holes and their host galaxies. Astrophys. J. 539, L9–L12 (2000)

    ADS  Article  Google Scholar 

  17. 17

    Gebhardt, K. et al. A relationship between the nuclear black hole mass and galaxy velocity dispersion. Astrophys. J. 539, L13–L16 (2000)

    ADS  Article  Google Scholar 

  18. 18

    Richards, G. T. et al. Broad emission-line shifts in quasars: an orientation measure for radio-quiet quasars? Astron. J. 124, 1–17 (2002)

    ADS  CAS  Article  Google Scholar 

  19. 19

    Haiman, Z. & Cen, R. A constraint on the gravitational lensing magnification and the age of the redshift z = 6.28 quasar SDSS 1030 + 0524. Astrophys. J. 578, 702–707 (2001)

    ADS  Article  Google Scholar 

  20. 20

    Elvis, M. et al. Atlas of quasar energy distributions. Astrophys. J. (Suppl.) 95, 1–68 (1995)

    ADS  Article  Google Scholar 

  21. 21

    Telfer, R. C., Zheng, W., Kriss, G. A. & Davidsen, A. F. The rest-frame extreme-ultraviolet spectral properties of quasi-stellar objects. Astrophys. J. 565, 773–785 (2002)

    ADS  CAS  Article  Google Scholar 

  22. 22

    Pentericci, L. et al. VLT optical and near-infrared observations of the z = 6.28 quasar SDSS J1030 + 0524. Astron. J. 123, 2151–2158 (2002)

    ADS  CAS  Article  Google Scholar 

  23. 23

    Heger, A. & Woosley, S. E. The nucleosynthetic signature of population III. Astrophys. J. 567, 532–543 (2002)

    ADS  CAS  Article  Google Scholar 

  24. 24

    Arnett, A. Massive star evolution and SN 1987A. Astrophys. J. 383, 295–307 (1991)

    ADS  Article  Google Scholar 

  25. 25

    Cen, R. Implications of WMAP observations on the population III star formation processes. Astrophys. J. Lett. (submitted)

  26. 26

    Kogut, A. et al. Wilkinson Microwave Anisotropy Probe (WMAP) first year observations: TE polarization. Astrophys. J. (submitted)

  27. 27

    Spergel, D. N. et al. First year Wilkinson Microwave Anisotropy Probe (WMAP) observations: determination of cosmological parameters. Astrophys. J. (submitted)

  28. 28

    Hu, E. M. et al. A redshift z = 6.56 galaxy behind the cluster Abell 370. Astrophys. J. 568, L75–L79 (2002)

    ADS  CAS  Article  Google Scholar 

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The VLA is operated by the National Radio Astronomy Observatory (NRAO), a facility of the National Science Foundation (NSF), operated under co-operative agreement by Associated Universities, Inc. (AUI). This work is based partly on observations carried out with the IRAM Plateau de Bure Interferometer. IRAM is supported by INSU/CNRS (France), MPG (Germany) and IGN (Spain). F.W. is a Jansky Fellow.

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Correspondence to Fabian Walter.

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Walter, F., Bertoldi, F., Carilli, C. et al. Molecular gas in the host galaxy of a quasar at redshift z = 6.42. Nature 424, 406–408 (2003).

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