LSU (Baton Rouge) Physics Ph.D. Program question

Hello!
On the lsu catalog for major descriptions, I found this block of text :

Formal requirements for the PhD degree include seven required courses (PHYS 7221, PHYS 7225, PHYS 7231, PHYS 7241, PHYS 7242, PHYS 7398, and PHYS 7857), 12 hours of advanced graduate courses beyond the required 19 core hours,

For " 12 hours of advanced graduate courses, " do these extra hours have to come from physics or can they be other courses such as math?