Who is the "author" of a file (Gnu "ls" manual)
I believe the author is the same as the owner unless you're using GNU/Hurd, in which case the two can be different. I haven't used Hurd, so I can only guess at the intended use of a unique author field.
I'm not aware of a --author flag in non-GNU versions of ls. It certainly doesn't exist in FreeBSD, which is the only other one I have easy access to right this minute.