Is dark matter essential for understanding galaxy interactions in clusters?

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Discussion Overview

The discussion centers on the role of dark matter in understanding galaxy interactions within clusters, particularly whether dark matter is essential for explaining the forces between galaxies or if visible matter suffices. Participants explore the implications of dark matter on the movement of galaxies, including M31's relationship with the Milky Way.

Discussion Character

  • Exploratory, Technical explanation, Debate/contested

Main Points Raised

  • One participant questions whether dark matter is necessary to explain the forces between galaxies or if visible matter alone can account for these interactions.
  • Another participant suggests that significant evidence for dark matter arises from analyzing the motion of galaxies in clusters, although they express uncertainty regarding the specific case of M31.
  • A historical perspective is provided, noting that Fritz Zwicky's observations of the Coma cluster were pivotal in the dark matter discourse, with current measurements relying on X-ray studies and gravitational lensing.
  • A participant mentions that while evidence for dark matter is linked to galaxy motion in clusters, the nature of dark matter remains unknown, complicating its use in calculations.
  • There is a suggestion that dark matter may be related to the acceleration of the universe's expansion, though this remains a theoretical proposition.

Areas of Agreement / Disagreement

Participants express varying views on the necessity of dark matter for explaining galaxy interactions, indicating that multiple competing perspectives exist without a clear consensus.

Contextual Notes

Some claims depend on historical observations and current methodologies, which may not fully resolve the complexities of dark matter's role in galaxy dynamics.

Who May Find This Useful

This discussion may be of interest to those exploring astrophysics, cosmology, and the ongoing debates surrounding dark matter and galaxy interactions.

twinsen
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Is dark matter required to explain the forces between galaxies or is it purely on a galactic scale.
Have there been any measures on dark matter in galactic clusters. Does M31 get influenced by dark matter in the milky way or does the visble matter in the milky way supply the required force to explain the movement of m31?

Alex
 
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I'm far from an expert in this area, but I think that a significant amount of evidence for dark matter comes from the analysis of the motion of galaxies in clusters.

I don't know anything about the M31-MW orbit, but I know that the LMC and SMC orbits are explained based on the Milky Way having a large dark matter halo.
 
The first hystorical clue for dark matter was found by Fritz Zwicky in 1933 by observations of the Coma galactic cluster. The rotation curves of spiral galaxies came later. Current observations that actually measure the distribution of gravitating matter (most of which seems dark) in clusters are based on X-ray studies of the cluster gas or graviational lensing.

If you want to be well informed about the history and contemporary research in dark matter/energy, I suggest reading "Dark Side of the Universe" by Iain Nicolson. It's without formulas but gives a very good account on the history of the subject and all contemporary collaborations working in that field, even future experiments planned.
 
Funnily enough I've just started a lecture course on this very topic!
...and cadnr, the evidence for dark matter does indeed come from analyzing motion of galaxies in clusters.

I don't think dark matter can actually be used in calculations yet because no-one actually knows what it is.

I believe it is theorized that dark matter (hence dark energy) is the reason the expansion of the universe is accelerating and not a constant expansion.
 

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