Skip to main content

Thank you for visiting You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

  • Letter
  • Published:

The Lyman-α glow of gas falling into the dark matter halo of a z = 3 galaxy


Quasars are the visible signatures of gas falling into the deep potential well of super-massive black holes in the centres of distant galaxies. It has been suggested1 that quasars are formed when two massive galaxies collide and merge, leading to the prediction that quasars should be found in the centres of regions of largest overdensity in the early Universe. In dark matter (DM)-dominated models of the early Universe, massive DM halos are predicted to attract the surrounding gas, which falls towards their centres. The neutral gas is not detectable in emission by itself, but gas falling into the ionizing cone of such a quasar will glow in the Lyman-α line of hydrogen, effectively imaging the DM halo2. Here we present a Lyα image of a DM halo at redshift z = 3, along with a two-dimensional spectrum of the gaseous halo. Our observations are best understood in the context of the standard model for DM haloes3; we infer a mass of (2 - 7) × 1012 solar masses (M) for the halo.

This is a preview of subscription content, access via your institution

Access options

Buy this article

Prices may be subject to local taxes which are calculated during checkout

Figure 1: Two-dimensional spectrum of Q1205-30 and the extended Lyα emission.
Figure 2: Narrow-band image of the extended Lyα emission compared to models.
Figure 3: Schematic presentation of the model.
Figure 4: Calculated surface brightness profile and projected velocity.

Similar content being viewed by others


  1. Carlberg, R. G. Quasar evolution via galaxy mergers. Astrophys. J. 350, 505–511 (1990)

    Article  ADS  Google Scholar 

  2. Haiman, Z. & Rees, M. Extended Lyα emission around young quasars: a constraint on galaxy formation. Astrophys. J. 556, 87–92 (2001)

    Article  ADS  CAS  Google Scholar 

  3. Navarro, J. F., Frenk, C. S. & White, S. D. M. A universal density profile from hierarchical clustering. Astrophys. J. 490, 493–508 (1997)

    Article  ADS  Google Scholar 

  4. Barkana, R. & Loeb, A. Spectral signature of cosmological infall of gas around the first quasars. Nature 421, 341–343 (2003)

    Article  ADS  CAS  Google Scholar 

  5. Fynbo, J. P. U., Thomsen, B. & Møller, P. Lyα emission from a Lyman limit absorber at z = 3.036. Astron. Astrophys. 353, 457–464 (2000)

    ADS  CAS  Google Scholar 

  6. Møller, P. Spectral PSF subtraction I: The SPSF look-up-table method. ESO Messenger 99, 31–33 (2000)

    ADS  Google Scholar 

  7. Møller, P., Warren, S. J., Fall, S. M., Jakobsen, P. & Fynbo, J. U. SPSF subtraction II: The extended Lyα emission of a radio quiet QSO. ESO Messenger 99, 33–35 (2000)

    ADS  Google Scholar 

  8. Bunker, A., Smith, J., Spinrad, H., Stern, D. & Warren, S. J. Illuminating protogalaxies? The discovery of extended Lyman-α emission around a QSO at z = 4.5. Astrophys. Space Sci. 284, 357–360 (2003)

    Article  ADS  CAS  Google Scholar 

  9. Gould, A. & Weinberg, D. H. Imaging the forest of Lyman limit systems. Astrophys. J. 468, 462–468 (1996)

    Article  ADS  CAS  Google Scholar 

  10. Barkana, R. A model for infall around virialized haloes. Mon. Not. R. Astron. Soc. 347, 59–66 (2004)

    Article  ADS  CAS  Google Scholar 

  11. Lawrence, A. The relative frequency of broad-lined and narrow-lined active galactic nuclei – Implications for unified schemes. Mon. Not. R. Astron. Soc. 252, 586–592 (1991)

    Article  ADS  CAS  Google Scholar 

  12. Elvis, M. A structure for quasars. Astrophys. J. 545, 63–76 (2000)

    Article  ADS  Google Scholar 

  13. Blundell, K. M., Beasley, A. J. & Bicknell, G. V. A relativistic jet in the radio-quiet quasar PG 1407 + 263. Astrophys. J. 591, L103–L106 (2003)

    Article  ADS  Google Scholar 

  14. Heckman, T. M., Lehnert, M. D., Miley, G. K. & van Breugel, W. Spectroscopy of spatially extended material around high-redshift radio-loud quasars. Astrophys. J. 381, 373–385 (1991)

    Article  ADS  CAS  Google Scholar 

Download references


This work was based on observations made with ESO telescopes at the Paranal Observatory.

Author information

Authors and Affiliations


Corresponding author

Correspondence to Michael Weidinger.

Ethics declarations

Competing interests

The authors declare that they have no competing financial interests.

Rights and permissions

Reprints and permissions

About this article

Cite this article

Weidinger, M., Møller, P. & Fynbo, J. The Lyman-α glow of gas falling into the dark matter halo of a z = 3 galaxy. Nature 430, 999–1001 (2004).

Download citation

  • Received:

  • Accepted:

  • Issue Date:

  • DOI:

This article is cited by


By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.


Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing