Uncovering the Reality of Dark Matter in Published Space Maps

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Discussion Overview

The discussion revolves around the nature and distribution of dark matter as observed in published space maps. Participants explore the relationship between dark matter and ordinary matter, its presence in various regions of space, and the implications for understanding cosmic structures. The conversation touches on theoretical aspects, observational challenges, and the significance of dark matter in galactic dynamics.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • Some participants note that dark matter appears to be present primarily in regions with visible mass, questioning whether this is a fact or a misconception.
  • Others propose that dark matter (DM) clumped first and its gravitational influence helped gather ordinary matter (OM), leading to higher densities of OM in certain areas.
  • It is suggested that while there is a correlation between regions of high DM density and high OM density, this correlation is not absolute, as some areas may contain low-density DM without significant OM.
  • One participant mentions that dark matter is thought to fill what would otherwise be considered empty space, referencing research that suggests it permeates intergalactic voids.
  • Concerns are raised about the difficulty of detecting dark matter, particularly in regions devoid of stars, as gravitational lensing and dynamics are often necessary for observation.
  • Some participants emphasize that dark matter exists primarily in the halos of galaxies, which plays a crucial role in preventing stars from escaping due to their velocities.
  • There is a reiteration that dark matter is more abundant than ordinary matter, with one participant expressing a preference for the view that galaxies exist within dark matter.

Areas of Agreement / Disagreement

Participants express multiple competing views regarding the relationship between dark matter and ordinary matter, as well as the implications of dark matter's distribution. The discussion remains unresolved, with no consensus reached on the nature of dark matter's presence in space maps.

Contextual Notes

Participants highlight limitations in observational techniques for dark matter, including the dependence on the presence of ordinary matter for measurement and the challenges posed by low-density regions. There are also unresolved questions about the methods used to create the space maps referenced in the discussion.

Tony Stark
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As observed in published space maps, I have noted that dark matter is present only in those region which already have visible mass around them. Is this really a fact or just my wrong belief?
 
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They are associated. In theory, DM because there is more of it, clumped first. And concentrations of DM helped to pull ordinary matter (OM) together by its gravity, leading to regions of higher than average density of OM.

So there is a correlation---regions where there is higher than average density of DM tend also to have pockets of higher than average density OM---not just visible in the form of stars but also gas, dust etc.

But the correlation wouldn't be absolute. there would be regions containing SOME dark matter, maybe just at very low density, in which no significant amount of OM had collected.

I'd be interested to see some of those maps, if you happen to have links to some online ones. DM is hard to detect except where it is in unusually high concentration and there are steep gradients in density that cause an optical distortion of the background (gravitational lensing). I wouldn't expect most DM to register that way---it would be too uniformly spread out. Maybe they just don't show DM where it is below a certain density. Anyway I'm wondering how the maps were made.
 
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'Dark matter' is now understood to fill what would otherwise be considered to be empty space.

'Cosmologists at Penn Weigh Cosmic Filaments and Voids'
http://www.upenn.edu/pennnews/news/cosmologists-penn-weigh-cosmic-filaments-and-voids

"Dark matter ... permeates all the way to the center of the voids."

'No Empty Space in the Universe --Dark Matter Discovered to Fill Intergalactic Space'
http://www.dailygalaxy.com/my_weblog/2012/02/no-empty-space-in-the-universe-dark-matter-discovered-to-fill-intergalactic-space-.html

"A long standing mystery on where the missing dark matter is has been solved by the research. There is no empty space in the universe. The intergalactic space is filled with dark matter."
 
marcus said:
They are associated. In theory, DM because there is more of it, clumped first. And concentrations of DM helped to pull ordinary matter (OM) together by its gravity, leading to regions of higher than average density of OM.

So there is a correlation---regions where there is higher than average density of DM tend also to have pockets of higher than average density OM---not just visible in the form of stars but also gas, dust etc.

But the correlation wouldn't be absolute. there would be regions containing SOME dark matter, maybe just at very low density, in which no significant amount of OM had collected.

I'd be interested to see some of those maps, if you happen to have links to some online ones. DM is hard to detect except where it is in unusually high concentration and there are steep gradients in density that cause an optical distortion of the background (gravitational lensing). I wouldn't expect most DM to register that way---it would be too uniformly spread out. Maybe they just don't show DM where it is below a certain density. Anyway I'm wondering how the maps were made.
That means my assumption is partially correct or wholly:smile::smile:
 
Where DM is most dense it has assisted ordinary matter to become more dense.
It's not so much a correlation as an inevitable consequence of gravity pulling matter together regardless of what sort of matter it is.
 
It is also quite hard to observe DM in the absence of stars in the vicinity with which one can measure either dynamics compared to a no DM hypothesis, or use lensing to measure it. It would take an incredible coincidence to have conditions right to observe DM effects if there was a random DM only clump in the middle of a large void.
 
Dark Matter mainly exists in the halos of galaxies meaning their outer ring and the fact that it exists in galaxies is very important and is one of the reasons the stars in galaxies do not fly away due to the rational velocities of the galaxies, so that extra mass holds it together.
 
Quds Akbar said:
Dark Matter mainly exists in the halos of galaxies meaning their outer ring and the fact that it exists in galaxies is very important and is one of the reasons the stars in galaxies do not fly away due to the rational velocities of the galaxies, so that extra mass holds it together.
I prefer to think of it that galaxies exist in dark matter. There is much more dark matter than their is matter.
 
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