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Dust-free quasars in the early Universe

Abstract

The most distant quasars known, at redshifts z ≈ 6, generally have properties indistinguishable from those of lower-redshift quasars in the rest-frame ultraviolet/optical and X-ray bands1,2,3. This puzzling result suggests that these distant quasars are evolved objects even though the Universe was only seven per cent of its current age at these redshifts. Recently one z ≈ 6 quasar was shown not to have any detectable emission from hot dust4, but it was unclear whether that indicated different hot-dust properties at high redshift or if it is simply an outlier. Here we report the discovery of a second quasar without hot-dust emission in a sample of 21 z ≈ 6 quasars. Such apparently hot-dust-free quasars have no counterparts at low redshift. Moreover, we demonstrate that the hot-dust abundance in the 21 quasars builds up in tandem with the growth of the central black hole, whereas at low redshift it is almost independent of the black hole mass. Thus z ≈ 6 quasars are indeed at an early evolutionary stage, with rapid mass accretion and dust formation. The two hot-dust-free quasars are likely to be first-generation quasars born in dust-free environments and are too young to have formed a detectable amount of hot dust around them.

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Figure 1: Spitzer SEDs of z  ≈ 6 quasars.
Figure 2: Luminosity and redshift dependence of the hot-dust abundance for type 1 quasars.
Figure 3: Correlation between the hot-dust abundance and black hole mass for type 1 quasars.

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References

  1. Fan, X. et al. A survey of z > 5.7 quasars in the Sloan Digital Sky Survey. III. Discovery of five additional quasars. Astron. J. 128, 515–522 (2004)

    Article  ADS  CAS  Google Scholar 

  2. Jiang, L. et al. Gemini near-infrared spectroscopy of luminous z 6 quasars: chemical abundances, black hole masses, and Mg II absorption. Astron. J. 134, 1150–1161 (2007)

    Article  ADS  CAS  Google Scholar 

  3. Shemmer, O. et al. Chandra observations of the highest redshift quasars from the Sloan Digital Sky Survey. Astrophys. J. 644, 86–99 (2006)

    Article  ADS  Google Scholar 

  4. Jiang, L. et al. Probing the evolution of infrared properties of z 6 quasars: Spitzer observations. Astron. J. 132, 2127–2134 (2006)

    Article  ADS  CAS  Google Scholar 

  5. Fan, X. et al. Constraining the evolution of the ionizing background and the epoch of reionization with z 6 quasars. II. A sample of 19 quasars. Astron. J. 132, 117–136 (2006)

    Article  ADS  CAS  Google Scholar 

  6. Willott, C. J. et al. Four quasars above redshift 6 discovered by the Canada-France High-z Quasar Survey. Astron. J. 134, 2435–2450 (2007)

    Article  ADS  CAS  Google Scholar 

  7. Kurk, J. D. et al. Black hole masses and enrichment of z 6 SDSS quasars. Astrophys. J. 669, 32–44 (2007)

    Article  ADS  CAS  Google Scholar 

  8. Antonucci, R. Unified models for active galactic nuclei and quasars. Annu. Rev. Astron. Astrophys. 31, 473–521 (2003)

    Article  ADS  Google Scholar 

  9. Elitzur, M. The toroidal obscuration of active galactic nuclei. N. Astron. Rev. 52, 274–288 (2008)

    Article  ADS  Google Scholar 

  10. Rieke, G. H. The infrared emission of Seyfert galaxies. Astrophys. J. 226, 550–558 (1978)

    Article  ADS  CAS  Google Scholar 

  11. Hyland, A. R. & Allen, D. A. An infrared study of quasars. Mon. Not. R. Astron. Soc. 199, 943–952 (1982)

    Article  ADS  CAS  Google Scholar 

  12. Haas, M. et al. The ISO view of Palomar-Green quasars. Astron. Astrophys. 402, 87–111 (2003)

    Article  ADS  Google Scholar 

  13. Richards, G. T. et al. Spectral energy distributions and multiwavelength selection of type 1 quasars. Astrophys. J. 166 (Suppl.). 470–497 (2006)

    Article  CAS  Google Scholar 

  14. Glikman, E., Helfand, D. J. & White, R. L. A near-infrared spectral template for quasars. Astrophys. J. 640, 579–591 (2006)

    Article  ADS  CAS  Google Scholar 

  15. Kurk, J. D. et al. Near-infrared spectroscopy of SDSS J0303–0019: a low-luminosity, high-Eddington-ratio quasar at z 6. Astrophys. J. 702, 833–837 (2009)

    Article  ADS  CAS  Google Scholar 

  16. Ryan, C. J., De Robertis, M. M., Virani, S., Laor, A. & Dawson, P. C. The central engines of narrow-line Seyfert 1 galaxies. Astrophys. J. 654, 799–813 (2007)

    Article  ADS  CAS  Google Scholar 

  17. Wang, R. et al. Millimeter and radio observations of z 6 quasars. Astron. J. 134, 617–627 (2007)

    Article  ADS  Google Scholar 

  18. Wang, R. et al. Thermal emission from warm dust in the most distant quasars. Astrophys. J. 687, 848–858 (2008)

    Article  ADS  CAS  Google Scholar 

  19. Hines, D. C. et al. Spitzer observations of high-redshift QSOs. Astrophys. J. 641, 85–88 (2006)

    Article  ADS  Google Scholar 

  20. Neugebauer, G. et al. Continuum energy distributions of quasars in the Palomar-Green Survey. Astrophys. J. 63 (Suppl.). 615–644 (1987)

    Article  CAS  Google Scholar 

  21. Haas, M. et al. Dust in PG quasars as seen by ISO. Astron. Astrophys. 354, 453–466 (2000)

    ADS  CAS  Google Scholar 

  22. Hernán-Caballero, A. et al. Mid-infrared spectroscopy of infrared-luminous galaxies at z 0.5–3. Mon. Not. R. Astron. Soc. 395, 1695–1722 (2009)

    Article  ADS  Google Scholar 

  23. Vestergaard, M. & Peterson, B. M. Determining central black hole masses in distant active galaxies and quasars. II. Improved optical and UV scaling relationships. Astrophys. J. 641, 689–709 (2006)

    Article  ADS  CAS  Google Scholar 

  24. Elvis, M., Marengo, M. & Karovska, M. Smoking quasars: a new source for cosmic dust. Astrophys. J. 567, 107–110 (2002)

    Article  ADS  Google Scholar 

  25. Maiolino, R. et al. A supernova origin for dust in a high-redshift quasar. Nature 431, 533–535 (2004)

    Article  ADS  CAS  Google Scholar 

  26. Stratta, G., Maiolino, R., Fiore, F. & D’Elia, V. Dust properties at z = 6.3 in the host galaxy of GRB 050904. Astrophys. J. 661, 9–12 (2007)

    Article  ADS  Google Scholar 

  27. Shen, Y., Greene, J. E., Strauss, M. A., Richards, G. T. & Schneider, D. P. Biases in virial black hole masses: an SDSS perspective. Astrophys. J. 680, 169–190 (2008)

    Article  ADS  CAS  Google Scholar 

  28. Barth, A. J., Martini, P., Nelson, C. H. & Ho, L. C. Iron emission in the z = 6.4 quasar SDSS J114816.64+525150.3. Astrophys. J. 594, 95–98 (2003)

    Article  ADS  Google Scholar 

  29. Vestergaard, M. & Osmer, P. S. Mass functions of the active black holes in distant quasars from the Large Bright Quasar Survey, the Bright Quasar Survey, and the color-selected sample of the SDSS fall equatorial stripe. Astrophys. J. 699, 800–816 (2009)

    Article  ADS  CAS  Google Scholar 

  30. Lavalley, M., Isobe, T. & Feigelson, E. in Astronomical Data Analysis Software and Systems I (eds Worrall, D. M., Biemesderfer, C. & Barnes, J.) 245–247 (ASP Conf. Ser. Vol. 25, Astronomical Society of the Pacific, 1992)

    Google Scholar 

Download references

Acknowledgements

This work is based on observations made with the Spitzer Space Telescope, which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under a contract with NASA. Support for this work was provided by NASA through an award issued by JPL/Caltech. X.F. acknowledges support by NSF AST, a Packard Fellowship for Science and Engineering, and a John Simon Guggenheim Memorial Fellowship. W.N.B. was supported by the NASA ADP program. C.L.C. thanks the Max-Planck-Gesellschaft and the Humboldt-Stiftung for support through the Max-Planck-Forschungspreis. J.D.K. thanks the DFG for support via German-Israeli Project Cooperation. The Dark Cosmology Centre is funded by the Danish National Research Foundation.

Author Contributions L.J. and X.F. designed the project, reduced and analysed the data, and prepared the manuscript; W.N.B., M.A.S. and F.W. performed statistics and edited the manuscript; C.L.C., E.E., D.C.H. and G.T.R. prepared observations; J.D.K. analysed NIR spectra of two hot-dust-free quasars; Y.S. and M.V. measured black hole masses. All authors helped with the scientific interpretations and commented on the manuscript.

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Correspondence to Linhua Jiang.

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Jiang, L., Fan, X., Brandt, W. et al. Dust-free quasars in the early Universe. Nature 464, 380–383 (2010). https://doi.org/10.1038/nature08877

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