17 September 2011

A prediction from PDM

A prediction from Parallel Dark Matter


Parallel Dark Matter is my (possibly entirely wrong) theory that dark matter is explained by 5 "parallel universes" that exchange only gravitational force with the visible universe. I presumptively call these parallel universes "branes" because they fit with braneworld cosmology.

Recent news and PDM

Recently astronomers found supermassive black holes growing in surprisingly small galaxies 1.
If PDM is true, a black hole in one brane is a black hole in all 6 branes and is fed by all 6 branes. This suggests that in the other branes the associated galaxy is bigger, by two arguments:
  • A "Where did the mass for the hole come from?" argument
  • A regression-to-means argument across branes

A prediction and possible test of PDM

So if PDM is true, we should find that these galaxies have disproportionate dark matter. If this is not true, then PDM will simply be wrong.
Quantitatively, I'd expect the amount of dark matter to be nearly in line with the size of the black holes. Ie, we should find that:
  1. The ratio of dark matter mass to black hole mass is nearly the same between these galaxies and massive early galaxies.
  2. The ratio of dark matter mass to whole galaxy mass is not at all the same between these galaxies and massive early galaxies.
But I don't understand galaxy formation well enough, so I'll play it safe and merely predict that factor (1) is more predictive of amount of dark matter than factor (2) is.
I'd also predict that, if it be established in the future that some otherwise similar galaxies have no central massive black hole, those galaxies will not have as much dark matter as these will (in ratio to galactic mass). No quantitative prediction here, just "less".

Possible confounding factors

Galaxies tend to be smaller the further back you go. As I read the article, these particular galaxies are even much smaller than the norm back then. If I misread that, then ignore this post.
These galaxies are about 10 billion years old, so the universe was about 1/4 its current age. If it were much younger, the parallel galaxies probably wouldn't have had time to form or to grow very big, and the above logic wouldn't hold (But then we'd barely be seeing visible galaxies either). AIUI 10 billion years ago is old enough.


1 University of California - Santa Cruz (2011, September 16). Small distant galaxies host supermassive black holes, astronomers find. ScienceDaily. Retrieved September 17, 2011, from http://www.sciencedaily.com/releases/2011/09/110915131601.htm

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