Wait and see if he responds , just the same as you would if you hadn't found he was "famous".
If your research thus far that you have shared with him is sound, and if he has any interest in pursuing it, then the fact that he is "famous" should make no difference at all to this, should it?
If, after a while (and, like any of us he may of course be a busy man) , you get no response then you will need to think if or how you will follow it up - the same as if you didn't get a response but had not discovered his "fame".