Collapsed structures in scalar-tensor theories of gravity

Abstract:
Dark energy represents perhaps the most relevant problem in cosmology. Light scalar fields coupled to matter could explain the accelerated expansion of the universe. This implies going beyond Lambda-CDM and the SM, yet there is no observation of such fifth forces in our solar system. This discrepancy can be resolved by a screening mechanism.

From the plethora of theories, we are interested in studying the chameleon field. The presence of this fifth interaction during the radiation-dominated era of the universe would change the structure formation history, alleviating some of the current cosmological tensions.

Moreover, the coupling of this field to compact objects, such as neutron stars or white dwarves, affects their structure, stability, and dynamics, providing us with some hints about its detectability.