Mixed fermion-boson stars are equilibrium solutions of the coupled Einstein Klein-Gordon-Euler system. While isolated neutron stars and boson stars are uniquely determined by their central energy density, mixed configurations conform an extended parameter space that depends on the combination of the number of fermions and (ultra- light) bosons. The wider possibilities offered by fermion-boson stars could help explain the tension in the measurements of neutron star masses and radii reported in recent multi-messenger observations (e.g. LVC gravitational wave observations and NICER/XMM-Newton measurements) and nuclear-physics experiments (PREX2).

Zoom session.