A new force in the dark sector?

Glennys R. Farrar, Rachel A. Rosen

    Research output: Contribution to journalArticlepeer-review


    We study the kinematics of dark matter using the massive cluster of galaxies 1E0657-56. The velocity of the "bullet" subcluster (actually, the bow shock velocity) has been measured by x-ray emission from the shock front, and the masses and separation of the main and subclusters have been measured by gravitational lensing. The velocity with gravity alone is calculated in a variety of models of the initial conditions, mass distribution, and accretion history; it is much higher than the velocity of the bow shock, by at least 2.4σ. The probability of so large a subcluster velocity in cosmological simulations estimated from the Hayashi-White fit is 10-7. A long-range force with strength ≈ 0.4-1.2 times that of gravity would provide the corresponding additional acceleration.

    Original languageEnglish (US)
    Article number171302
    JournalPhysical Review Letters
    Issue number17
    StatePublished - Apr 24 2007

    ASJC Scopus subject areas

    • General Physics and Astronomy


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