Neutron-star mass limit in the bimetric theory of gravitation

The "neutron"-star upper mass limit is examined in Rosen's bimetric theory of gravitation. An exact solution, approximate scaling law, and numerical integration of the hydrostatic equilibrium equation show the dependence of the mass limit on the assumed equation of state. As in general relativity, that limit varies roughly as 1ρ0, where ρ0 is the density above which the equation of state becomes "stiff." Unlike general relativity, the stiffer the equation of state, the higher the mass limit. For ρ0=2×1014 g/cm3 and P=(ρ-ρ0)c2, we found Mmax=81M. This mass is consistent with causality and experimental tests of gravitation and nuclear physics. For dpdρ>c2 it appears that the upper mass limit can become arbitrarily large.