what is the meaning of なの here


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。




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:

  * X は Y かもしれない → _X could be Y_
  * X は Y **なの** かもしれない → _It could be that X is Y_

For example, if you heard someone coming down the chimney on Christmas Eve,
you would say:

> あの音はサンタさん **かもしれない** ！  
>  _That sound could be Santa!_

But if you didn't hear anyone coming down the chimney all night, you would
say:

> サンタさんはお父さん **なのかもしれない** ！  
>  _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:

  * それ自体が宇宙かもしれない _It might be a universe in itself_
  * それ自体が宇宙 **なの** かもしれない _One might say that it is a universe in itself_

