On the maximum mass limit of neutron stars in scalar-tensor gravity

Abstract

The maximum mass limits of neutron stars in scalar-tensor gravity is discussed and compared with the limits set by general relativity. The limit is parametrized with respect to the combination of the nuclear saturation parameters and the maximum sound velocity in the core. It is shown that, for smaller values of the sound velocity in the core, the maximum mass limit of the scalarized neutron stars is larger than that of in general relativity. However, for stiff equations of state with sound velocity higher than $79\%$ of the velocity of light, the maximum mass limit in general relativity is larger than that of in scalar-tensor gravity. The results suggest that future observations of massive neutron stars, may constrain the maximum sound velocity as well as the coupling parameter in scalar-tensor gravity.