Scalar-tensor gravity models are among the prime candidates to explain cosmic acceleration, and compact stars provide unique laboratories for testing such theories. Predictions of scalar-tensor gravity in compact stars can be examined during the evolution of neutron stars. Spontaneous scalarization in relativistic stars is influenced by different properties of stellar matter in various evolution regimes. In the present study, we investigate the scalarization of neutron stars in different stages of the evolvement. For this aim, we apply the isentropic equations of state for the neutron star matter including nucleons, hyperons, and $\mathrm{\Delta }$-resonances in neutrino-trapped, neutrino diffusion, and neutrino-transparent stages as well as cold-catalyzed neutron star. Our equations of state are based on the relativistic model within the mean-field approximation. To emphasize the role of scalar-tensor theories in exploring the properties and structure of compact stars, we calculate the structure of neutron stars with hyperons and $\mathrm{\Delta }$-resonances in different snapshots of the neutron star evolution in the scalar-tensor gravity. Our calculations confirm that the neutron star scalarization is affected by the hyperons as well as the $\mathrm{\Delta }$-resonances. Moreover, the properties of scalarized neutron stars depend on the stage of the star evolution.

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• Alternative gravity theories
• Formation & evolution of stars & galaxies
• General relativity
• Gravitation
• Neutron star cooling
• Novae & supernovae
• Neutron stars & pulsars