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The anomalies of the halo model of dark matter have begun to accumulate rapidly. The problems of the halo model are discussed in detail in the blog “Dark matter crisis” of Prof. Pavel Kroupa and Marcel S. Pawlowski (see this). MOND is the most well-known competitor of the halo model for dark matter but has its own problems. TGD is less known alternative for the halo model. In the following brief comments about Zwicky paradox (see this) implying that neither cold nor warm dark matter particles in the usual sense (different from that in TGD based model) can play a significant role in cosmology.
The standard/concordance model of dark matter relies on two hypothesis formulated originally by Zwicky assuming that a) GRT is correct in all scales and b) all matter is created during Big Bang. Zwicky formulated two hypothesis (for references see the article) leading to the halo model of dark matter and also to Zwicky paradox.
From these observations one ends up with a computer model allowing to simulate the formation of galaxies (for a detailed discussion see this). The basic elements of the model are collisions of galaxies possibly leading to a fusion and formation of tidal galaxies. The model assumes a statistical distribution of dark matter lumps defining the halos of the dwarf galaxies formed in the process.
The model predicts a lot of dark matter dominated dwarf galaxies formed around the dark matter lumps: velocity spectrum should approach constant. There are also tidal dwarf galaxies formed from collision debris of other galaxies. Unless also now condensation around a dark matter lump is involved, these should not contain dark matter and velocity spectrum for tidal dwarfs should be declining. It turns out that tidal dwarfs alone are able to explain the observed dwarf galaxies, which are typically elliptic. Furthermore, there is no empirical manner to distinguish between tidal dwarfs and other dwarfs.
Do the elliptic galaxies contain dark matter? What does one know about the rotation curves of elliptic galaxies? There is an article “The rotation curves of elliptic galaxies” of J. Binney published around 1979 about the determination of the rotation curves of elliptic galaxies giving also some applications (see this). The velocity curves are declining as if no dark matter were present. Therefore dark matter would not be present in dwarf galaxies so that the prediction of the halo model would be wrong.
Could this finding be also a problem for MOND? Assuming that the laws governing gravitation are modified for small accelerations, shouldn’t elliptic and spiral galaxies have similar velocity curves?
What about TGD?
For a summary of earlier postings see Latest progress in TGD.
Articles and other material related to TGD.