Tuesday, October 18, 2011

Cold Dark Matter Inconsistent With Dwarf Galaxy Observations

Cold dark matter theories predict a much more uneven distribution of dark matter than is observed in dwarf galaxies that are believed to be 99% composed of dark matter. The actual distribution observed is even over a large area. This basically reiterates conference papers reported earlier in this space about the increasing evidence for warm dark matter rather than cold dark matter theories.

The main implication of this is that searches for dark matter with particles in the GeV range and up are probably looking for something that the data from astronomy does not support as a dark matter candidate.

Since, all weak force interacting particles of 45 GeV or less are ruled out by precision electroweak data, this rules out a fundamental particle that interacts with the weak force as a dark matter candidate. And, there are no massive fundamental particles in the Standard Model that do not interact via the weak force. For that matter, higher generation Standard Model particles, and the lighest supersymmetric particle in most SUSY theories are also ruled out on account of being too heavy if cold dark matter theories are incorrect.

Ordinary neutrinos are what astronomers call "hot dark matter" and are believed to be too light (and hence too fast) to fit the data either. All known mesons and all baryons other than protons and neutrons are incredibly unstable and there is no process in the universe that could create them quickly enough.

We think we know enough about protons and neutrons and the process by which they come to be (baryogenesis) to rule out baryonic dark matter (e.g. interstellar hydrogen gas or gas giants floating unattached to any star) as well. Exotic hadron "molecules" made of more than one meson, which have been observed in charm factories, are also too heavy and too unstable.

This leaves us with a "crime" that every known possible culprit has been ruled out from committing.

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