Akhenaten
Heretic Pharaoh
There was no sonic boom. I don't know why. Any proposed reason would be pure speculation based on technology that we haven't even shown to be plausible yet ( e.g. antigravity ).
j.r.
No, any proposed reason would require a suspension of the laws of physics that dictate that an object moving through the air at 50,000 kph is going to make quite a racket, and the fact that your story doesn't include this makes it even more improbable than it already was.