Does modified gravity somehow explain galaxies that don't need it?

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Discussion Overview

The discussion revolves around the role of modified gravity in explaining the behavior of certain galaxies that appear to not require dark matter for their observed properties. Participants explore the implications of these observations within the frameworks of modified gravity and traditional dark matter theories.

Discussion Character

  • Debate/contested

Main Points Raised

  • One participant questions how proponents of modified gravity account for galaxies that do not exhibit behaviors necessitating dark matter or modified gravity.
  • Another participant seeks clarification on which specific galaxies are being referenced in the discussion.
  • A third participant provides examples of galaxies, such as those mentioned in popular articles, that seem to behave as if they contain only visible matter.
  • A later reply discusses NGC1277, noting that both ΛCDM and MOND models suggest a deficit of dark matter in certain types of galaxies, indicating a potential overlap in interpretations.
  • The same reply also mentions DF2 and DF4 as special cases, highlighting uncertainties regarding their distance and the implications of their observations.
  • One participant cautions that popular articles may not accurately represent the findings of the original research papers.

Areas of Agreement / Disagreement

Participants do not reach a consensus, as multiple competing views regarding the interpretation of galaxy behavior and the necessity of dark matter or modified gravity remain present.

Contextual Notes

There are limitations in the discussion, including uncertainties about the distances of certain galaxies and the reliance on interpretations from popular sources versus original research.

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How do proponents of modified gravity explain the fact of observation of galaxies, the behaviour of matter in which does not require an explanation in the form of dark matter or modified gravity?
 
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Which galaxies are you speaking of?
 
NGC1277 is a lenticular galaxy, in between being rotationally and pressure supported. ΛCDM says those galaxies in general have a deficit of DM, and MOND says the acceleration is above the MOND turn-on. So both models say the same thing.

DF2 and DF4 are special, but a) AFAIK no other examples have been found, b) the interpretatiom depends on their distance, and c) there is some evidence that they are closer than supposed.

As a PS, popular articles tend to be substantially worse sources than the actual paper.
 
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