Can I do theoretical physics in an astrophysics candidates, masters?

[rocket123456]

What do I lose from an astronomy/astrophysics candidates course, contrasted with a theoretical physics degree?

Astrophysics is broader, and in that sense more appealing. However, I wonder if I am allowed to write about quantum mechanics as an undergraduate, in a theoretical astrophysics paper? Do I need to infer it in a cosmic - all encompassing "astronomical way", to make it a legitimate astrophysics paper?

My other interests being the big bang-theory vs (Quasi) Steady-state theory, and just physics overall.

The eventual job prospects being an astrophysicist seems much more promising these days as well, in some very specific job descriptions. Though both have very similar level of education.

 

[rocket123456]

In other words: Astrophysics deals(among other things) with the physics of the universe. Quantum mechanical theories are, as any other physical theory, connected to the function of the universe - and most certainly leave interesting implications regarding the gravitational discrepencys between the microscopic and macroscopic parts of the world, if the main stream interpretations are true.