Speaker: Roxana Rosca-Mead (University of Jena)

Title: Core collapse in massive scalar-tensor theory: Phenomenology and observational potential

Abstract:

Though general relativity has been successfully tested so far, concepts such as dark energy and string theory suggest the need of modifying it. Scalar-tensor theory is one of the most popular alternatives discussed. We produce studies of stellar core collapse in spherical symmetry in which we systematically explore the parameter space that characterizes the progenitor stars, the equation of state and the scalar-tensor theory of the core collapse events. We identify a remarkably simple and straightforward classification scheme of the resulting collapse events. For any given set of parameters, the collapse leads to one of three end states, a weakly scalarized neutron star, a strongly scalarized neutron star or a black hole, possibly formed in multiple stages. The latter two end states can lead to strong gravitational-wave signals that may be detectable in present continuous-wave searches with ground-based detectors. The dispersive nature of the propagation of waves in the massive scalar field mean the gravitational wave signals are long lived and many such signals can overlap to form a stochastic background. Using different models for the population of supernova events in the nearby universe, we compute predictions for the energy-density in the stochastic scalar-polarized gravitational wave background from core-collapse events in massive scalar-tensor gravity for theory parameters that facilitate strong scalarization.

Room: Sala de Reuniões e Seminários (2-8.3) (2nd Floor of Physics Building)