How long-range interactions tune the damping in compact stars

Long-range interactions lead to non-Fermi liquid effects in dense matter. We show that, in contrast to other material properties, their effect on the bulk viscosity of quark matter is significant since they shift its resonant maximum and can thereby change the viscosity by many orders of magnitude. This is of importance for the damping of oscillations of compact stars, like in particular unstable r-modes, and the quest to detect signatures of deconfined matter in astrophysical observations. We find that, in contrast to neutron stars with standard damping mechanisms, compact stars that contain ungapped quark matter are consistent with the observed data on low mass x-ray binaries.