Sep 26 – 28, 2018
Department of Physics (University of Coimbra)
Europe/Lisbon timezone

Cooling of hypernuclear compact stars

Sep 27, 2018, 8:30 AM
Room E10A

Room E10A


Dr Adriana Raduta


We study the thermal evolution of hypernuclear compact stars
constructed from covariant density functional theory of hypernuclear
matter and parameterizations which produce sequences of stars
containing two-solar-mass objects. For the input in the simulations,
we solve the BCS 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 $M/M_{\odot} \ge 1.5$ 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 $1.5 \le M/M_{\odot} \le 1.8$ 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 $M/M_{\odot} \simeq 2$ 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.

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