It seems I can remove it and keep the same meaning...
暗黒物質は自然界の新しい種類の力を介して相互作用する雑多な粒子の集まりからなり，それ自体が私たちの宇宙にひっそりと絡み合う1 つの宇宙 なのかもしれない。
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There is a slight difference between 〜かもしれない and 〜なのかもしれない that is really hard to explain, but is nonetheless good to know because in a lot of cases one will be much more natural than the other.
One way to look at it might be:
For example, if you heard someone coming down the chimney on Christmas Eve, you would say:
That sound could be Santa!
But if you didn't hear anyone coming down the chimney all night, you would say:
It could be that Santa is Dad!
Or if you offended your friend last week and are afraid of seeing her again, you might say 「まだ怒ってるかもしれないから会いたくない (I don't want to see her because she could still be angry)」. But if she seems to be ignoring your calls since you've offended her, you might say to yourself 「まだ怒ってるのかもしれない (It could be that she is still angry)」.
So in your specific example, another way to translate the difference in nuance is: