Fourth order gravity, scalar-tensor-vector gravity, and galaxy rotation curves
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Publication Details
Output type: Journal article
Author list: Mishra P, Singh TP
Publisher: American Physical Society
Publication year: 2013
Journal: Physical Review D (1550-7998)
Volume number: 88
Issue number: 10
ISSN: 1550-7998
eISSN: 1550-2368
Languages: English-Great Britain (EN-GB)
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Open access status: green
Full text URL: https://arxiv.org/pdf/1108.2375
Abstract
The lambda-CDM model is the best fit to cosmological data and to the observed galactic rotation curves. However, in the absence of a direct detection of dark matter one should explore theories such as modified Newtonian dynamics (MOND), and perhaps also modified gravity theories like fourth order gravity and scalar-tensor-vector gravity (STVG) as possible explanations for the non-Keplerian behavior of galaxy rotation curves. STVG has a modified law for gravitational acceleration which attempts to fit data by fixing two free parameters. We show that, remarkably, the biharmonic equation which we get in the weak field limit of the field equations in a fourth order gravity theory implies a modification of Newtonian acceleration which is precisely of the same repulsive Yukawa form as in the STVG theory, and the corrections could in principle be large enough to try and explain the observed rotation curves. We also explain how our model provides a first principles understanding of MOND. We also show that STVG and fourth order gravity predict an acceleration parameter a(0) whose value is of the same order as in MOND.
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