Neutrino diagnostics of hadron-quark phase transition in Neutron Stars

Abstract

We investigate neutrino signatures of a hadron-quark phase transition (HQPT) in neutron stars (NS) leading to quark star (QS) formation. We use representative hadronic and quark equations of state i.e. DD2 and MIT bag model along with a phenomenological neutrino emission model including the dominant leptonic and hadronic processes. Rather than aiming at a fully consistent hydrodynamical simulation, our goal is to identify generic temporal diagnostics that may arise when deconfinement occurs during the evolution of a compact star. We identify characteristic diagnostic features that may emerge in the neutrino light curve on $\simeq 10-50$ ms timescales. These include an enhanced peak-to-plateau ratio, a delay tracing the central density evolution, and a transient spectral hardening. After standard MSW flavor conversion, these temporal and spectral signatures remain potentially detectable for Galactic events under optimistic assumptions with detectors such as IceCube and Hyper-Kamiokande. Our results suggest possible temporal and spectral diagnostics of quark deconfinement in future Galactic neutrino bursts.