Neutrinos from Neutron Stars

Speaker(s) Joachim Kopp (CERN)

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We discuss neutrino emission processes from neutron stars. After reviewing the classic Urca cooling reactions, which produce a large flux at undetectably low energy, we comment on two new processes: muon diffusion and decay in neutron stars away from chemical equilibrium, and neutrino cooling of common-envelope systems. The latter are systems where a compact object (e.g. a neutron star) is engulfed by a binary companion, starts accreting at an enormous rate, and radiates away gravitational energy in neutrinos. Common-envelope evolution is believed to be crucial for the formation of LIGO/VIRGO/KAGRA gravitational wave sources, and we show that neutrinos might offer an opportunity to directly observe this process for the first time.