Cooling of hypernuclear compact stars

We study the thermal evolution of hypernuclear compact stars constructed from covariant density functional theory of hypernuclear matter and parametrizations which produce sequences of stars containing two-solar-mass objects. For the input in the simulations, we solve the Bardeen-Cooper-Schrieffer gap equations in the hyperonic sector and obtain the gaps in the spectra of Lambda, Xi(0), and Xi(-) hyperons. For the models with masses M/M-circle dot >= 1.5 the neutrino cooling is dominated by hyperonic direct Urca processes in general. In the low-mass stars the (Lambda p) plus leptons channel is the dominant direct Urca process, whereas for more massive stars the purely hyperonic channels (Sigma(-)Lambda) and (Xi(-)Lambda) are dominant. Hyperonic pairing strongly suppresses the processes on Xi(-)s and to a lesser degree on Lambda s. We find that intermediate-mass 1.5 <= M/M-circle dot <= 1.8 models have surface temperatures which lie within the range inferred from thermally emitting neutron stars, if the hyperonic pairing is taken into account. Most massive models with M/M-circle dot similar or equal to 2 may cool very fast via the direct Urca process through the (Lambda p) channel because they develop inner cores where the S-wave pairing of Lambda s and proton is absent.