Journal Article

A novel MOND effect in isolated high-acceleration systems

Mordehai Milgrom

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 426, issue 1, pages 673-678
Published in print October 2012 | ISSN: 0035-8711
Published online October 2012 | e-ISSN: 1365-2966 | DOI:
A novel MOND effect in isolated high-acceleration systems

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We discuss a novel MOND effect that entails a correction to the dynamics of isolated mass systems even when they are deep in the Newtonian regime: systems whose extent RrM, where rM ≡ (GMt/a0)1/2 is the MOND radius and Mt is the total mass. Interestingly, even if the MOND equations approach Newtonian dynamics arbitrarily fast at high accelerations, this correction decreases only as a power of R/rM. The effect appears in formulations of MOND as modified gravity, governed by generalizations of the Poisson equation. The MOND correction to the potential is a quadrupole field is the radius from the centre of mass. In quasilinear MOND (QUMOND), is the quadrupole moment of the system and α > 0 is a numerical factor that depends on the interpolating function. For example, the correction to the Newtonian force between two masses, m and M, a distance ℓ apart (ℓ ≪ rM) is (attractive). Its strength relative to the Newtonian force is ). For generic MOND theories, which approach Newtonian dynamics quickly for accelerations beyond a0, the predicted strength of the effect in the Solar system is rather much below present testing capabilities. In MOND theories that become Newtonian only beyond κa0, the effect is enhanced by κ2.

Keywords: galaxies: kinematics and dynamics

Journal Article.  4735 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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