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arXiv · 2407.12493

Bulk viscosity of two-color superconducting quark matter in neutron star mergers

Mark Alford·Arus Harutyunyan·Armen Sedrakian·Stefanos Tsiopelas
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Abstract

We study the bulk viscosity of moderately hot and dense, neutrino-transparent color superconducting quark matter arising from weak-interaction-driven direct URCA processes. The quark matter is modeled using the Nambu--Jona-Lasinio model improved to account for vector and 't Hooft interactions as well as antisymmetric pairing among the red/green up and down quarks. The unpaired excitations are the strange quarks and the blue up or down quarks. We compute the relaxation rates associated with $d$ and $s$-quark decay and electron capture processes on $u$ quark for blue color. The resulting bulk viscosity for density oscillations in the 1--10\,kHz range shows a resonant peak at $T\sim 5\,\MeV$, and the damping time may drop below 10 ms. This is short enough to affect the postmerger evolution and is very similar to the damping predicted in nuclear matter.

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Mark Alford, Arus Harutyunyan, Armen Sedrakian, Stefanos Tsiopelas. 2024-07-17. Bulk viscosity of two-color superconducting quark matter in neutron star mergers. https://doi.org/10.1103/physrevd.110.l061303

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