Two-scalar field stellar configurations in Einstein gravity

Abstract

We develop a model of Einstein gravity coupled to two scalar fields that admits exact analytical solutions representing a realistic compact stellar object. To this end, we derive the equations of motion describing a spherically symmetric spacetime within this framework. The resulting system consists of three equations involving eight unknown functions: three associated with the scalar field coefficients, three arising from the energy–momentum tensor components, and two corresponding to the metric potentials. It is shown that one scalar field coefficient vanishes identically, reducing the number of unknowns to seven. To close the system, four additional constraints are imposed, including two equations of state one radial and one tangential, and specified forms for the metric potentials. This approach yields explicit expressions for the energy density and the two scalar field coefficients. We then evaluate the model against physical requirements such as the regularity of the energy–momentum tensor components at the stellar center and verify that the mass function aligns with observations from the pulsar PSR J0740+6620. Finally, we analyze the mass–radius relation and apply best-fit techniques to the equations of state, confirming their consistency with the imposed assumptions.