Modified Newtonian Dynamics (MOND): Observational Phenomenology and Relativistic Extensions

By B. Famaey, S. McGaugh. Living Reviews in Relativity, 2011

697 citations recorded by the source corpus.

A wealth of astronomical data indicate the presence of mass discrepancies in the Universe. The motions observed in a variety of classes of extragalactic systems exceed what can be explained by the mass visible in stars and gas. Either (i) there is a vast amount of unseen mass in some novel form — dark matter — or (ii) the data indicate a breakdown of our understanding of dynamics on the relevant scales, or (iii) both. Here, we first review a few outstanding challenges for the dark matter interpretation of mass discrepancies in galaxies, purely based on observations and independently of any alternative theoretical framework. We then show that many of these puzzling observations are predicted by one single relation — Milgrom’s law — involving an acceleration constant a0 (or a characteristic surface density Σ† = a0/G) on the order of the square-root of the cosmological constant in natural units. This relation can at present most easily be interpreted as the effect of a single universal force law resulting from a modification of Newtonian dynamics (MOND) on galactic scales. We exhaustively review the current observational successes and problems of this alternative paradigm at all astrophysical scales, and summarize the various theoretical attempts (TeVeS, GEA, BIMOND, and others) made to effectively embed this modification of Newtonian dynamics within a relativistic theory of gravity.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/18a5adf5b5ba2168fa19593e6e1495b4f731effe

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Citations in the corpus

History of dark matter (2018, positive): “For reviews, see Skordis (2009) and Famaey and McGaugh (2012).”
Galaxy Masses: A Review (2013, methodology): “Readers interested in alternative models, MOND or others, are referred to the review by Famaey & McGaugh (2012).”
Small scale problems of the $\Lambda$CDM model: a short review (2016, methodology): “At cluster scales, nonetheless, MOND proves much less successful (however, see [359] for a different point of view).”
Dynamical boson stars (2012, background): “Perhaps the most well known of these is MOND (modified Newtonian dynamics) in which gravity is modified only at large distances [364, 365] (for a review see [184]).”
Theory of dark matter superfluidity (2015, background): “Figure 1, reproduced from [6], shows excellent agreement with remarkably little scatter in the high-mass end comprised of star-dominated (dark blue circles) and gas-dominated disc galaxies (light blue circles).”
A DIRECT DYNAMICAL MEASUREMENT OF THE MILKY WAY'S DISK SURFACE DENSITY PROFILE, DISK SCALE LENGTH, AND DARK MATTER PROFILE AT 4 kpc ≲ R ≲ 9 kpc (2013, background): “…MOND theory of modified gravity the local surface-density to 1.1 kpc is predicted to be enhanced with respect to the contribution from baryonic matter by & 60% 8 (Nipoti et al. 2007; Bienaymé et al. 2009; Famaey & McGaugh 2012), such that we expect for Σbaryonic(R0) = 51 ± 4M⊙ pc −2 that ΣMOND1.”
Galaxies as simple dynamical systems: observational data disfavor dark matter and stochastic star formation (2014, methodology): “So far no clear evidence for SID has been found ( [11]; see also the Ibata/Sanders disagreement: [232]).”
Bouncing cosmology in f(Q) symmetric teleparallel gravity (2020, neutral): “[19] B.”
Dwarf galaxy planes: the discovery of symmetric structures in the Local Group (2013, background): “…are seriously over-estimated (e.g. McConnachie & Côté 2010), the underlying assumption that the galaxies are bound systems is invalid (Kroupa 1997; Klessen & Kroupa 1998; Casas et al. 2012) or the underlying dynamics is non-Newtonian (Angus 2008; Famaey & McGaugh 2012; McGaugh & Milgrom 2013).”
General Relativity and Cosmology: Unsolved Questions and Future Directions (2016, background): “They include experiments such as laser ranging off the Moon (lunar laser ranging) and several of the Earth’s artificial satellites [372–375], and proposals to extend laser ranging to other planets in the Solar System (planetary laser ranging) [376–380], radar astrometry on near-Earth objects [381], ”
One Law to Rule Them All: The Radial Acceleration Relation of Galaxies (2016, background): “60 of Famaey & McGaugh (2012): gobs = ( gbar +ghost ) ν ( gbar + ghost a0 ) −ghost ν ( ghost a0 ) , (24) where ν is the interpolation function (equivalent to the shape of the radial acceleration relation).”