Review of Evidence for Dark Matter

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Discussion Overview

The discussion centers around the evidence for dark matter (DM), referencing a review article by Matts Roos that summarizes various astrophysical and cosmological probes supporting the existence of dark matter. Participants explore different types of evidence, including rotation curves and big bang nucleosynthesis, while also touching on ongoing detection efforts and related controversies.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants highlight the usefulness of Roos's article, noting it provides a comprehensive overview of evidence for dark matter beyond just rotation curves.
  • One participant expresses concern that the review underplays the significance of big bang nucleosynthesis (BBN) as evidence for nonbaryonic dark matter, suggesting it may be the strongest evidence available.
  • Another participant mentions the unresolved issues related to lithium abundances in BBN and questions whether these have been addressed in recent literature.
  • There is acknowledgment of the contradictory results from direct detection experiments, with some participants expressing interest in understanding the true nature of dark matter in light of these challenges.

Areas of Agreement / Disagreement

Participants generally agree on the value of the review article and the importance of empirical evidence for dark matter. However, there are competing views regarding the significance of different types of evidence, particularly concerning big bang nucleosynthesis and its implications.

Contextual Notes

Participants note limitations in the review, such as its focus on astrophysical and cosmological evidence while excluding ongoing detection efforts, which are described as preliminary and controversial. The discussion also highlights unresolved issues related to lithium abundances in BBN.

marcus
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There are several types of evidence for DM and Helsinki scientist Matts Roos provides a 39 page overview listing and summarizing each kind. It's a useful article. He gives graphic figures to illustrate each type of evidence.

http://arxiv.org/abs/1208.3662
Astrophysical and cosmological probes of dark matter
Matts Roos
(Submitted on 17 Aug 2012)
Dark matter has been introduced to explain mass deficits noted at different astronomical scales, in galaxies, groups of galaxies, clusters, superclusters and even across the full horizon. Dark matter makes itself felt only through its gravitational effects. This review summarizes phenomenologically all the astrophysical and cosmological probes that have been used to give evidence for its existence.
39 pages, 24 figures. Accepted by J. of Modern Physics and will be released as Special Issue in September, 2012

The Bullet Cluster evidence, that everybody seems to know about, comes on page 28.
People new to the subject of DM might benefit by at least leafing thru and glancing at the pictures.

This review paper only covers the astrophysical and cosmological evidence. There are also several ongoing efforts to detect DM particles. Results from that work are preliminary and controversial--and were outside the scope of Roos's review.
 
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This is a very useful article, thanks for posting. I often argue with people who think that rotation curves are the sole evidence for DM, so it will be nice to have this list handy.
 
Thanks, marcus, for posting this valuable summary of evidence for Dark Matter. As much as I try to disallow DM with non-scientific emotion it is reassuring to regress back into the land of empirical evidence.

Bobbywhy
 
Excellent article. Thanks Marcus!
 
Thanks, Marcus, very nice.

I found it odd that the paper underplayed big bang nucleosynthesis so strongly. I would consider the relative abundances of hydrogen, helium, and deuterium to be the single strongest piece of evidence for nonbaryonic dark matter, and yet I can't find anything in the paper directly discussing it.

BBN is also the only source of evidence I'm aware of that shows any serious problem with the current models, because of the lithium issue: arxiv.org/abs/0808.2818, arxiv.org/abs/1107.1117 . Has this been resolved since those papers were published?

It's too bad that the direct detection experiments are such a mess of contradictory results. Since SUSY seems to be mortally wounded, it would be interesting to find out what dark matter really consists of.
 
Last edited:
This is the most recent 'solution' proposed for the lithium problem -
Neutron injection during primordial nucleosynthesis alleviates the primordial 7Li problem http://arxiv.org/abs/1208.0443
 

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