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Early gas stripping as the origin of the darkest galaxies in the Universe


The known galaxies most dominated by dark matter (Draco, Ursa Minor and Andromeda IX) are satellites of the Milky Way and the Andromeda galaxies1,2,3,4. They are members of a class of faint galaxies, devoid of gas, known as dwarf spheroidals3,4,5, and have by far the highest ratio of dark to luminous matter3,6. None of the models proposed to unravel their origin7,8,9,10 can simultaneously explain their exceptional dark matter content and their proximity to a much larger galaxy. Here we report simulations showing that the progenitors of these galaxies were probably gas-dominated dwarf galaxies that became satellites of a larger galaxy earlier than the other dwarf spheroidals. We find that a combination of tidal shocks and ram pressure swept away the entire gas content of such progenitors about ten billion years ago because heating by the cosmic ultraviolet background kept the gas loosely bound: a tiny stellar component embedded in a relatively massive dark halo survived until today. All luminous galaxies should be surrounded by a few extremely dark-matter-dominated dwarf spheroidal satellites, and these should have the shortest orbital periods among dwarf spheroidals because they were accreted early.

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Figure 1: Morphological evolution of the dwarf galaxy satellite.
Figure 2: Structural properties of the simulated dwarf after 10 billion years of evolution.


  1. Mateo, M. Dwarf galaxies of the local group. Annu. Rev. Astron. Astrophys. 36, 435–506 (1998)

    Article  ADS  CAS  Google Scholar 

  2. Grebel, E. K. in The Stellar Content of Local Group Galaxies (eds Whitelock, P. & Cannon, R.) 17–38 (IAU Symposium 192, ASP, San Francisco, 1999)

    Google Scholar 

  3. Kleyna, J. T., Wilkinson, M. I., Evans, N. W., Gilmore, G. & Frayn, C. Dark matter in dwarf spheroidals—II. Observations and modeling of Draco. Mon. Not. R. Astron. Soc. 330, 778–791 (2002)

    Article  ADS  Google Scholar 

  4. Chapman, S. et al. Keck DEIMOS kinematic study of Andromeda IX: Dark matter on the smallest galactic scales. Astrophys. J. 632, L87–L90 (2005)

    Article  ADS  CAS  Google Scholar 

  5. Gallagher, J. S., Madsen, G. J., Reynolds, R. J., Grebel, E. K. & Smecker-Hane, T. A. A search for ionized gas in the Draco and Ursa Minor dwarf spheroidal galaxies. Astrophys. J. 588, 326–330 (2003)

    Article  ADS  Google Scholar 

  6. Kazantzidis, S. et al. Density profiles of cold dark matter substructure: implications for the missing-satellites problem. Astrophys. J. 608, 663–679 (2004)

    Article  ADS  Google Scholar 

  7. Lin, D. N. C. & Faber, S. M. Some implications of nonluminous matter in dwarf spheroidal galaxies. Astrophys. J. 266, L21–L25 (1983)

    Article  ADS  Google Scholar 

  8. Dekel, A. & Silk, J. The origin of dwarf galaxies, cold dark matter, and biased galaxy formation. Astrophys. J. 303, 39–55 (1986)

    Article  ADS  CAS  Google Scholar 

  9. Bullock, J., Kravtsov, A. & Weinberg, D. H. Reionization and the abundance of galactic satellites. Astrophys. J. 539, 517–521 (2000)

    Article  ADS  Google Scholar 

  10. Mayer, L. et al. The metamorphosis of tidally stirred dwarf galaxies. Astrophys. J. 559, 754–784 (2001)

    Article  ADS  Google Scholar 

  11. de Blok, W. J. G. & McGaugh, S. S. The dark and visible matter content of low surface brightness disc galaxies. Mon. Not. R. Astron. Soc. 290, 533–552 (1997)

    Article  ADS  Google Scholar 

  12. Mayer, L. & Moore, B. The baryonic mass-velocity relation: clues to feedback processes during structure formation and the cosmic baryon inventory. Mon. Not. R. Astron. Soc. 354, 477–484 (2004)

    Article  ADS  Google Scholar 

  13. Susa, H. & Umemura, M. Formation of dwarf galaxies during the cosmic reionization. Astrophys. J. 600, 1–16 (2004)

    Article  ADS  CAS  Google Scholar 

  14. Mac Low, M. M. & Ferrara, A. Starburst-driven mass loss from dwarf galaxies: efficiency and metal ejection. Astrophys. J. 513, 142–155 (1999)

    Article  ADS  Google Scholar 

  15. Einasto, J., Kaasik, A. & Saar, E. Dynamic evidence on massive coronas of galaxies. Nature 252, 111–113 (1974)

    Article  ADS  Google Scholar 

  16. Marcolini, A., Brighenti, F. & D'Ercole, A. Three-dimensional simulations of the interstellar medium in dwarf galaxies—I. Ram pressure stripping. Mon. Not. R. Astron. Soc. 345, 1329–1339 (2003)

    Article  ADS  Google Scholar 

  17. Mori, M. & Burkert, A. Gas stripping of dwarf galaxies in clusters of galaxies. Astrophys. J. 538, 559–568 (2000)

    Article  ADS  CAS  Google Scholar 

  18. Kravtsov, A. V., Gnedin, O. Y. & Klypin, A. A. The tumultuous lives of galactic dwarfs and the missing satellites problem. Astrophys. J. 609, 482–497 (2004)

    Article  ADS  CAS  Google Scholar 

  19. Diemand, J., Madau, P. & Moore, B. The distribution and kinematics of early high-sigma peaks in present-day haloes: implications for rare objects and old stellar populations. Mon. Not. R. Astron. Soc. 364, 367–383 (2005)

    Article  ADS  Google Scholar 

  20. Governato, F. et al. The formation of a realistic disk galaxy in lambda-dominated cosmologies. Astrophys. J. 607, 688–696 (2004)

    Article  ADS  CAS  Google Scholar 

  21. Verde, L., Oh, P. S. & Jimenez, R. The abundance of dark galaxies. Mon. Not. R. Astron. Soc. 336, 541–549 (2002)

    Article  ADS  Google Scholar 

  22. Haardt, F. & Madau, P. Radiative transfer in a clumpy universe. II. The ultraviolet extragalactic background. Astrophys. J. 461, 20–37 (1996)

    Article  ADS  CAS  Google Scholar 

  23. Gunn, J. E. & Gott, J. R. I. On the infall of matter into clusters of galaxies and some effects on their evolution. Astrophys. J. 176, 1–19 (1972)

    Article  ADS  Google Scholar 

  24. Munoz, R. P. et al. Exploring halo substructure with giant stars: the velocity dispersion profiles of the Ursa Minor and Draco Dwarf spheroidal galaxies at large angular separations. Astrophys. J. 631, L137–L141 (2005)

    Article  ADS  Google Scholar 

  25. Willman, B., Governato, F., Dalcanton, J. J., Reed, D. & Quinn, T. The observed and predicted spatial distribution of Milky Way satellites. Mon. Not. R. Astron. Soc. 353, 639–646 (2004)

    Article  ADS  Google Scholar 

  26. Moore, B. et al. Dark matter substructure within galactic halos. Astrophys. J. 524, L19–L22 (1999)

    Article  ADS  CAS  Google Scholar 

  27. Willman, B. et al. A new Milky Way dwarf galaxy in Ursa Major. Astrophys. J. 626, L85–L88 (2005)

    Article  ADS  Google Scholar 

  28. Kleyna, J. T., Wilkinson, M. I., Evans, N. W. & Gilmore, G. Ursa Major:a missing low mass CDM halo? Astrophys. J. 630, L141–L144 (2005)

    Article  ADS  CAS  Google Scholar 

  29. Walker, M. G. et al. Internal kinematics of the Fornax dwarf spheroidal galaxy. Astron. J. 131, 2114–2139 (2006)

    Article  ADS  Google Scholar 

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We thank Y. Birinboim, A. Dekel, F. Governato, A. Kravtsov, G. Lake, C. Porciani, M. Valluri, B. Willman and A. Zentner, for discussions. We also thank S. Majewski and R. Munoz for sharing their data with us. L. Mayer and S. Kazantzidis are grateful to the Aspen Center for Physics, where some of this work was completed. All computations were performed on the Zbox supercomputer at the University of Zürich, on LeMieux at the Pittsburgh Supercomputing Center, and on the Gonzales cluster at ETH Zürich.

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Correspondence to L. Mayer or S. Kazantzidis.

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Mayer, L., Kazantzidis, S., Mastropietro, C. et al. Early gas stripping as the origin of the darkest galaxies in the Universe. Nature 445, 738–740 (2007).

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