WASHINGTON (Reuters) – A balloon-borne instrument soaring high over Antarctica has found evidence of a possible large clump of mysterious so-called dark matter relatively close to our solar system, scientists said on Wednesday
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One explanation is that the electrons may have been spawned as dark matter particles collided with one another, triggering their mutual annihilation, according to Louisiana State University physics professor John Wefel.

Scientists think perhaps 25 percent of the universe is made up of dark matter, which responds to gravity the same way as does regular matter such as stars and planets and the like.
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Scientists think regular matter amounts to about 5 percent of the universe's mass. The remaining roughly 70 percent is thought to be composed of dark energy, a mysterious presence that may be making the universe expand at an accelerated pace.