Collapsing spherical stars in f(R) gravity

Understand

We perform a careful investigation of the problem of physically realistic gravitational collapse of massive stars in f(R)-gravity.

• We show that the extra matching conditions that arise in the modified gravity imposes strong constraints on the stellar structure and thermodynamic properties.
• In our opinion these constraints are unphysical.
• We prove that no homogeneous stars with non-constant Ricci scalar can be matched smoothly with a static exterior for any nonlinear function f(R).