If it is established that the Earth does have a dark matter disk as this recent discovery suggests.


Then could the Earth have a dark matter core as well as a disk?


Presumably the distribution described in the article is the one that the data support. That implies that the data don't really support some other distribution.

Now NewScientist in a basically a pop-sci venue so they may be simplifying the report, but the paper doesn't seem to offer an analysis on the limits of the result. Indeed this seems to be a pretty sketchy, first-pass type analysis.

  • $\begingroup$ Yep however if the Earth can slow dark matter down enough to form a disk then would a core form as well? $\endgroup$ – Jitter Jan 3 '14 at 17:54
  • $\begingroup$ @Jitter But dark matter doesn't form a disk (it has a very hard time exchanging angular momentum with anything, including itself), and there is no reason to believe it is clumped up here anyway. That paper has to stretch things extremely far in order to keep it's idea alive, and a number of experiments have already ruled out the parameter space the author wants to work in. $\endgroup$ – user10851 Feb 2 '14 at 19:56
  • $\begingroup$ Would dark matter lose/gain angular momentum during gravitational slingshots? $\endgroup$ – Jitter Feb 3 '14 at 7:15
  • $\begingroup$ @Jitter Yes, but it will as much of one as the other. On average it simply randomizes the vectors. The systems has to cool to form a disk and that is very hard for something with the properties of dark matter. To the point that the temperature of the presumed galactic dark matter halo is one way to estimate the interaction cross-section (but, of course, the resulting limits are mass dependent). $\endgroup$ – dmckee --- ex-moderator kitten Feb 3 '14 at 16:25

1) There is no consistent empirical detection of dark matter, arXiv:1310.4009, 0906.0668; arXiv:1310.8214, 1306.5534, 1306.3983. Quite the contrary.
2) Dark matter can be a curve fit of Milgrom acceleration. Milgrom acceleration can arise in a wholly natural, universal, and bench top testable way (off-topic here).
3) There is no mechanism for dark matter to cool from the Big Bang until now, then be orbitally diddled.
4) If dark matter could be disked, galaxies would not have a spherical dark matter distribution necessary to curve-fit the Tully-Fisher relation.
5) If a galaxy has a spherical cloud distribution of gravitationally bound hot dark matter curve-fitting Tully-Fisher, what keeps dark matter from being scavenged by each galaxy's central giant black hole, with fireworks?

No dark matter at all. No fancy dark matter orbits or sequestrations short of extreme gravitational wells (black holes, neutron stars, maybe white dwarfs) for its uncooling temperature.

  • $\begingroup$ 3) Maybe DM has no "heat" to start with and has no mechanism to carry any or absorb any. Is there some law that says all particles must be hot during the BB? $\endgroup$ – Jitter Feb 3 '14 at 7:30
  • $\begingroup$ There is no mechanism for dark matter to cool? The De-Broglie wavelength is stretched by the universal expansion just as it is for photons, for neutrinos et al. What keeps dark matter from being scavenged - its angular momentum, the same as all the other matter in a galaxy. Why no fireworks? Because it is dark matter. $\endgroup$ – Rob Jeffries Apr 15 '15 at 11:12

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