### 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 language | English (US) |
---|---|

Pages (from-to) | 513-530 |

Number of pages | 18 |

Journal | Modern Physics Letters A |

Volume | 16 |

Issue number | 8 |

DOIs | |

State | Published - Mar 14 2001 |

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### ASJC Scopus subject areas

- Physics and Astronomy(all)
- Statistical and Nonlinear Physics
- Mathematical Physics
- Nuclear and High Energy Physics

### Cite this

*Modern Physics Letters A*,

*16*(8), 513-530. https://doi.org/10.1142/S0217732301003206

**Ultralight scalars and spiral galaxies.** / Dvali, Gia; Gabadadze, Gregory; Shifman, M.

Research output: Contribution to journal › Article

*Modern Physics Letters A*, vol. 16, no. 8, pp. 513-530. https://doi.org/10.1142/S0217732301003206

}

TY - JOUR

T1 - Ultralight scalars and spiral galaxies

AU - Dvali, Gia

AU - Gabadadze, Gregory

AU - Shifman, M.

PY - 2001/3/14

Y1 - 2001/3/14

N2 - 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.

AB - 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.

UR - http://www.scopus.com/inward/record.url?scp=0035857868&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0035857868&partnerID=8YFLogxK

U2 - 10.1142/S0217732301003206

DO - 10.1142/S0217732301003206

M3 - Article

VL - 16

SP - 513

EP - 530

JO - Modern Physics Letters A

JF - Modern Physics Letters A

SN - 0217-7323

IS - 8

ER -