Micaela Oertel (Observatoire Astronomique de Strasbourg, France)

:Dark matter constitutes more than 85% of the matter in the universe, yet it remains a challenging puzzle in physics. Numerous experimental and astronomical efforts aim to shed light on its nature, and neutron stars offer a natural laboratory for probing dark matter through their extreme densities and gravitational fields. In this talk, I will discuss the impacts of bosonic dark matter on neutron stars’ equation of state and observable features, focusing on scenarios where dark matter is captured or produced inside them. In the first part, I will focus on sub-GeV, self-interacting bosonic dark matter defined by a complex scalar field that interacts with baryonic matter only through gravity. In this model, dark matter can reside as a dense core inside a neutron star or form an extended halo around it. I will show how multimessenger observations, which constrain neutron star mass, radius, and tidal deformability, impose limits on the dark matter mass, coupling constant, and its fraction inside neutron stars. In the second part, I will discuss the production of a bosonic dark matter particle and its effect on the fundamental (f-mode) oscillations of neutron stars. We show that bosonic dark matter systematically shifts the f-mode frequency and damping time, altering the usual quasi-universal f-mode relations. These deviations encode dark matter effects while preserving practical universality for inference, and they can be probed with future gravitational-wave telescopes.