Ultralight scalars and spiral galaxies

Gia Dvali, Gregory Gabadadze, M. Shifman

    Research output: Contribution to journalArticlepeer-review

    Abstract

    We study some possible astrophysical implications of a very weakly coupled ultralight dilaton-type scalar field. Such a field may develop an (approximately stable) network of domain walls. The domain wall thickness is assumed to be comparable with the thickness of the luminous part of the spiral galaxies. The walls provide trapping for galactic matter. This is used to motivate the very existence of the spiral galaxies. A zero-mode existing on the domain wall is a massless scalar particle confined to (1 + 2) dimensions. At distances much larger than the galaxy/wall thickness, the zero-mode exchange generates a logarithmic potential, acting as an additional term with respect to Newton's gravity. The logarithmic term naturally leads to constant rotational velocities at the periphery. We estimate the scalar field coupling to the matter energy-momentum tensor needed to fit the observable flat rotational curves of the spiral galaxies. The value of this coupling turns out to be reasonable - we find no contradiction with the existing data.

    Original languageEnglish (US)
    Pages (from-to)513-530
    Number of pages18
    JournalModern Physics Letters A
    Volume16
    Issue number8
    DOIs
    StatePublished - Mar 14 2001

    ASJC Scopus subject areas

    • Nuclear and High Energy Physics
    • Astronomy and Astrophysics
    • Physics and Astronomy(all)

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