Oh please! This is getting embarrassing for Dark Matter enthusiasts.
They might as well just admit now that Dark Matter doesn't exist, and
that this is all caused by gravity from normal baryonic matter acting in
ways that Newton or Einstein never imagined, i.e. MOND.

Yousuf Khan

These new dark matter particles would essentially consist of heavy
"dark protons" and light "dark electrons." They would interact with
each other far more than other dark matter particles to form "dark
atoms" that use "dark photons" to interact through a sort of "dark
electromagnetism," much as regular protons and electrons interact
through photons in conventional electromagnetism to build the atoms
making up the stuff of everyday life. If dark atoms are possible,
they could react with each other for dark chemistry, much as regular
atoms interact chemically.

The interactions between dark protons and dark electrons could make
them lose energy over time. As such, they might slow down enough to
clump into flat disks around galaxies, just like regular matter does.
In contrast, most dark matter apparently forms roughly spherical
haloes around galaxies, stars and planets.

This concept means galaxies would have two disks, one made of regular
atoms and one of dark atoms, which is why the investigators call
their idea the double-disk dark matter model.

New Kind of Dark Matter Could Form 'Dark Atoms' | Dark Disk Universe |
Space.com
http://www.space.com/21508-dark-matt...l?cmpid=514630