Transport properties of superfluid phonons in neutron stars

  • We review the effective field theory associated with the superfluid phonons that we use for the study of transport properties in the core of superfluid neutrons stars in their low temperature regime. We then discuss the shear and bulk viscosities together with the thermal conductivity coming from the collisions of superfluid phonons in neutron stars. With regard to shear, bulk, and thermal transport coefficients, the phonon collisional processes are obtained in terms of the equation of state and the superfluid gap. We compare the shear coefficient due to the interaction among superfluid phonons with other dominant processes in neutron stars, such as electron collisions. We also analyze the possible consequences for the r-mode instability in neutron stars. As for the bulk viscosities, we determine that phonon collisions contribute decisively to the bulk viscosities inside neutron stars. For the thermal conductivity resulting from phonon collisions, we find that it is temperature independent well below the transition temperature. We also obtain that the thermal conductivity due to superfluid phonons dominates over the one resulting from electron-muon interactions once phonons are in the hydrodynamic regime. As the phonons couple to the Z electroweak gauge boson, we estimate the associated neutrino emissivity. We also briefly comment on how the superfluid phonon interactions are modified in the presence of a gravitational field or in a moving background.

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Author:Cristina Manuel, Laura TolósORCiD
Parent Title (English):Universe
Place of publication:Basel
Document Type:Article
Date of Publication (online):2021/03/05
Date of first Publication:2021/03/05
Publishing Institution:Universitätsbibliothek Johann Christian Senckenberg
Release Date:2021/10/19
Tag:effective theories; neutrino emissivity; superfluid phonons; transport coefficients
Issue:3, art. 59
Page Number:22
First Page:1
Last Page:22
This research was supported by the Spanish Ministerio de Economía y Competitividad under Contract FPA2016-81114-P, Ministerio de Ciencia e Innovación under Contract PID2019-110165GB-I00, and by the EU STRONG-2020 project under the program H2020-INFRAIA-2018-1, Grant Agreement No. 824093. This work was also supported by the COST Action CA16214 PHAROS: The multimessenger physics and astrophysics of neutron stars.
Institutes:Wissenschaftliche Zentren und koordinierte Programme / Frankfurt Institute for Advanced Studies (FIAS)
Dewey Decimal Classification:5 Naturwissenschaften und Mathematik / 53 Physik / 530 Physik
Licence (German):License LogoCreative Commons - Namensnennung 4.0