What initial speed must the proton have for consistency with our observed final “dragged down” speed (assuming some ballpark galactic distance)? Alternatively,

What initial speed must the proton have for consistency with our observed final “dragged down” speed (assuming some ballpark galactic distance)? Alternatively, could a “clump” of particles have smashed into our detector? Whatever the new physics winds up explaining this bonkers momentum, it’ll be fascinating.